ETC TOP233

匾也温室主壶室主-
TOP232-234
TOPSwifch@ -FX 系列
采用 EcoSmart@ 节能技术的
离线式集成开关电源
产品特色
+
降低系统成本，提高设计灵活性
•
节约外国 )C 件成卒
•
集成了软启动功能，使启动压力/过冲
减至最小
•
外部可精确设定流限
占空比更宽，功率更大，输入电容更小
•
线欠压 (UV) 保护:消除 f 关断故障
•
线过压 (OV) 关断限制电涌现象
•
降低前馈的最大占空比 (DC MAx) ，防止也
•
压技波、并将高电压输入时，切定 DC MAx
TOPSwitch-FX
PI.2503.073099
图 1 、典型的反激式应用
通过同一电阻设定 OV/UV 门限、降低 DC MAx
•
采用频率抖动降低 EMI 及 EMI 滤波费用
•
无需虚拟负载即可调节至零负载
•
频率 130kHz ，变压器/电源尺寸更小
•
为视频应用提供频率减半边项
•
滞后热关断使器件可臼动恢复工作
•
热滞后值较大，防止电路板过热
•
省略部分号|脚的标准工业封装加强了高压
号|脚的漏电距离
•
可用远程开关功能启动或关断
•
能与较低频率同步
输出JjJ 率表
器件序号3
230VAC 士 15%
注释
VAC
敞式搁架 2
适配器l
敞式搁架 ι
9W
才 5W
6.5W
10W
10W
25W
25W
7W
9W •
15W
丁 3W
20W
16W
50W
30W
15W
11W
30W
20W
30W
75W
20W
45W
TOP232P
TOP232G
TOP232Y
TOP233P
TOP233G
TOP233Y
TOP234P
TOP234G
TOP234Y
EcoSmart- 提高能效
85 到 265
适配器1
丁 5W
1 , 50 C 无通风豆豆闭环境下测得的典型持纯功率 J
0
2 , 50 C 带足够散热装置的敞式搁架设汁中测得
0
的实际最大持续功率细节请参见应用关挝
•
跳过周期能降低空载功耗
•
远程关断模式降低功耗
•
为高效待机应用提供频率减半边项
•
可以通过周域网 (LAN) /输入端口关
3 ，封装
P:DIP - 8B , G:SMD -8B ， Y: 四 220-7B.
外部精确流限的设定，能用于远程通/断或使
振荡器与外部的较低频率的信号同步。另一项
断或启动
是频率 (F) 号|脚，仅 Y封装提供。通常此引!即与
源极相连，当它与控制l 弓!脚( C) 相连时，能提
说明
供频率减半边项。这两条新引!即提供的功能也
TOPSwitch-FX采用与 TOPSwitch 相同的拓扑电
路，并以高'陀{介比集成 f 多项新功能。这些功
能不仅能降低系统成本，同时还能提高设计的
灵活性、性能和效能.它不仅像 TOPSwitch 一样
在一片 CMOS 芯片中集成了高压功率 MOSFET 、
脉冲调宽 (PWM) 控制器、故障自动保护和所有
其它控制电路，还增加了两项。第一项是多功
能号|脚 (M) ，通过线电压实现可编程过压/欠压
关断设定和降低前馈 IDCMAXO
此弓|脚还能替代
可以通过将其与源极短路采取消，
{吏器件以三
端的 TOPSwitch 模式工作，但具备以下新特性:
软启动、跳过周期、开关频率 130kHz 、频率抖
动、
DC MAx 更宽、热滞后关断且漏电电压更大
另外，频率、流限，、
P阳增益等重要参数与
TOPSwitch-1I 系列相比，植度和绝对容差更小。
高流限精度和大 DC MAX ，加上其它特性，
TOPSwitch-FX与同等的 TOPSwitchll相比，在相
同输入/输出条件下功率高
10% 到
15% 。
··皿且重宝y空军DRALN (口}
CONTROL(C)
"•5.8 V
4.8 V
CURRENT LIMIT
COMPARATOR
RE
50URCE (5)
PI-2535-083099
图 2 、功能框图
控制弓l 脚 (C) :
弓l 脚功能描述
用于占空比控制的误差放大器和反馈电流
的输入脚 2
漏极弓|脚 (0) :
与内部并联艳、压器相连接，捉
住正常工作时的内部偏置电流。也用作电
高压功率 MOSFETi届极号!脚的输出。通
;原旁路和l 自动主启动/补偿电容的连接点.
过内部的开关式高压电流源 i是供启动偏
置电 tit:。漏极电流的内部流限检测点。
多功能弓l 脚 (M) :
源极弓|脚:
与高压功率回路连接的
MOSFET~.原极寻!脚
的输出.初级控制j 电路的公共点和参考点.
过压 (OV) ，欠压 (UV) ，降低 DC MAX 的前馈、流
限外部设毒、远程通 /Wf和同步的输入号|
TO-220 (Y07B)
咽。嘈
?'zuaaT
脚。连接源极寻|脚则取消此号!脚所有功
能，使
TOPSwitch-FX 以简单的三端
频率弓l 脚 (F)
(仅限 Y封装) :
E
模式工作(像 TOPSwitch-1/ )。
DFSMC
/
Tab Internally
Connected to
50urce Pin
选择开关频率的输入引脚:如果连接源
DIP-8 (P08B)
SMD-8 (G08B)
M1
85
52
75
极寻|脚为 130kHz ，连接控制号|脚为 65
53
kHzo
P 和 G 封装只能以 130kHz 升关频率
C4
工作。
PI.25 口 1.072199
罔 3 、弓 i 脚结构
2
5D
匾血温室主量宝~
TOPSwitch-FX 系列器件功能描述
TOPSwitchFX 是与 TOPSwitch
Auto-restart
/
样的 42 成
P\?附M Gain
式开关电源芯片，能将控制输入电流转化为
高月二功率 MOSFET 的源漏输山的占空比 C
J二作情况下，
正'启
r)J 率 MOSFET 的占空比陆控制引
脚屯流的增加而线性减小，如同 4A斤 /J二
TOPSwitchFX 除了 f象三端 TOPSwitch
具有高n;:启动、逐周期流限、
'8
主 47
u
-0=3h
一样，
1.5
M 路补位 l 包
1.5 1.9
路、自动重启动、热关断等特性，还综合了
5.55.9
'c(mA)
PI-25 口 4-072799
i午多能降低系统成本、提高电源性能和设计
灵活性的附加功能。
TOPSwitchFX 采用了专利
因 4 、占空比与控制脚电流的关系
高压 CMOS 技术，能以占主高性价比将高吓功，仨
MOSFET 丰rl 所有低压控制电路集成到一片集成
电路中。
控制弓|脚工作
控制!即是接收电源和反馈组合屯 ifii 的低阻
TOPSwitch-FX 增加了两个用于实现某片
新功能的端脚频率(仅限 Y 封装)丰11 多功能引
抗节点。在 iE 常工作用间，用并耳其稳而器米分
脚。它们与源极寻|脚边按时，能使 TOPSwitch­
离反馈信号和电源电流 O
FX 以 TOPSwitch 二端模式工作相问的。{o
;\ìIJ 电路(包括 MOSFET i' ]驱动器在内)的电压
使在这种二揣模式中，
HIJ
TOPSwitch-FX 也能提
快许多下述功能而元需额外外})口外田元
件:
1.
源，直 t! 连接控制)郎和源脚的外接旁路屯容捉
快瞬时门驱动电流。连接到控制脚的全部电容
也用于设定自动重启动的定时，同时控制环路
集成完整的 10ms 软民动，削减启动时的 w年
的补{尝 O
值也流丰rl 电rr:并消除了大多数应用中的输
启动时，经整流的直流高压}Jn在漏极弓 1 1)却
出过冲
上，
2.
控制脚的电!王 V c 是控
DCMAxoJ 达 78% ，允许使用更小的输入有储
电容，所需输入电压更低或提供的输山 r)J
率更高
MOSFET lti 初关断，通过庄挂在漏极和l 控
制!因之间的内部高压开关电 idLj原比电流泪对控
制!即仁的电容充电。当控制!因电压 V c 接近 5.8V
时，控制电路被激活并开始软启动。在 10ms 左
3.
最小脉宽时以跳过周期实现调节，能使空
载功耗极低
4.
右时间内，软启动电路使 MOSFET 的占雪比从
零逐渐 1 :升到最大倪。在软启动结束时，如果
采用较高的 '130kHz 开关频率，可减小变 rF
没有外部反馈/电源电沈 iii 入控制弓|时，则高
器尺寸，而且对 EMI 和 l 效率几乎没有影响
压电流泪关断，控制!即开始根据控制电路消耗
5.
频率抖动功能可降低 EMI
电源电流的大小放电 O
6.
滞后过热关断功能确保它能从热故隙中自
动恢复。滞后时间较大，可防止电路板过
于A
7.
采用缺省部份引脚和号 l 线的主才装，能提供
更大的漏极漏电距离
如果电视;设计正确，而
且不存在开环写文输出短路等故障时，在控制脚
电压放电到接近 4.8V 下限屯!五值(内部电源欠
压锁定门限值)之前，反馈环路将闭台，提供
控制号 1 ，即外部电流。:':í外部注入的电流对控制
!即充电到 5.8V 并联程、压器电压时，超过芯片所
消耗的电流通过电阻 R E 分;在到源极引脚，如图
8.
绝对容差更小，温度变化到开关频率、流
限和 PWM 增益的影响减小
2 所后
O
流经 R E 的电流控制j 功率 MOSFET 的占全
比，实现闲合环路调节。在采用丰i)J 级反馈结构
3
·血温室y空军E
时，并联稳压器很低的输出阻抗 Zc 决定误差放
大器的增益。控制脚的动态阻抗 Zc 和外接电阻
振荡器
内部的振荡器使内部的电容在两个设定
的电压值之间线性充放电，以产生脉宽调制
电容一起共同决定控制环路的主极点。
当出现开环或输出短路等故障而使外部电
流无法流入控制脚时，控制脚上的电容开始放
器所需的锯齿波电压。在每个周期的起点，
振荡器将脉克调制器/电流限制的门问电路琶
电，达到 4.8V 时激活自动重启动而关断 M08FET
输出，使控制电路进入低电流的待机模式，高
压电流源再次接通并对外接电容充电。内部的
滞后电源欠压比较器通过使高压电流源通断米
保持 Vd直处于典型的 4.8V到 5.8V 的区域内，如
罔 5 所示。自动重启动电路中有-个除 8 的计数
器，仅在计满( 87 )时才接通输出 M08FE了，
用以防止输出 M08FET在八个放电充电周期过
额走开关频率选择 130KHz ，
{吏变压器尺
寸最小日电磁寸二扰基频低于 150kHz 。频率寻|
脚(仅限 TO-220 封装)与控制脚短接时，开关频
率降至 65kHz (频率减半) ，这种特性在对噪声
敏恩的中见切;j J年用或高波率的待机模式中非常
有用:如果与源极引脚相连，则开关频率为
指定值 130kHz 。可调节基准电流米改善振荡
器的频率度，为 f 使 EMI 电平更低，开关频率以
去前重新导通此计数器通过将自动重启动的占
250Hz 速率(典刑值)采用大约:t 4kHz 抖动(频率调
空比减到典型值 4% 米有效地限制 TOP8witch 平X
制) ，如图 6 所示。图 28 中的测量，值显示了增加
的功耗。自动重启动模式将不断循环工作直
频率抖动后对 EMI 的改善。
到输出电压通过闭合反馈环路重新进入受控状
态为止。
\~
VL1NE
。v
56 ",-- 57
肝→一_5.8V
.\r\::::;r-\:;.---\/←一
Vc
4.8V
。v
①
司，
①
④
Note: 50 through 57 are the output states of the auto-restart counter
图 5、
4
(1 )上电 (2) 正常工作 (3) 自动重启动和 (4) 电源关断时的典型波形
PI.2545ο82299
E血温室m空军E
误差放大器
脉宽调制器和最大占空比
在初级反馈应用中，并联稳!主器也能起到
脉宽调击IJ 器通过驱动输出 MOSFET 来实现电压
误差放大器的作用。
模式控制，其占空比与超过芯片内部电源电
见图
流而流经控制脚的电流成反比(
4 )。
这
L]
1川
们叼/
部份电流在 R E 两端产生的反馈误差信号(
以降低芯片电 ~t~ 电 ijfi 中由
OSFET 门驱动器产生的开关噪声的影响。
流增大时，
产生占空比的波 Jl:; ,
占空比减小。
电路 1ri 号 ñf 位在 V c 屯!五上。
可外部编程的片内流限
由振荡器产生的时
化前，
注意:
连同的峰值漏电流限制电路以输出 MOSFET
的导通电阳作为检测电阻。
在占空比开始变
但
最大占空比 DC MAx 为固定 78%( 典电值)。
(
V DS(ON)
)与一个问值电压相比较" , 漏极电流大
大将使 VDS(O刊)阻过阀值电)主并在下一个时钟周
当多功能弓|脚通过怡当的电阻与
经整流的直流高压总线相连时，
流限比较器将输出
MOSFET 导通状态下的漏一源极间的电压
最小电流必须注入控制脚。
如图 8 所示，
控制脚电流扭过电
控制电
脉宽调制器使此门|习电路复位
f(iî 关断输出 MOSFET 0
控制引脚将外部
成误差电压信号。
钟信号将一个门问电路置位从而使输出
OSFET 导通。
误差放大器的增益
j原电流的部分通过并联稳压器分离，流经 R E 形
经
滤波的误差信号与内部振荡器产生的锯齿波
信号进行比较，
于借温度补偿的带隙基准 1
山控制弓|脚的动态阻抗决定 O
图 2 )通过一个截止频率典型值为 7KHz 的 RC 屯
路进行洁、泼，
精确的并耳其稳压电压来自
用开始 wr 关断输出 MOSFET o
|始输入电压
TOPSwitch-FX的固
的增加，最大占空比可以从 78% 阵至 38%( 典明
定限 j;[ {直己在内部预先设定，
值)(参见 DC MAx 降低的纹路前馈 )
多功能!由和明、!剧间的电阻，
0
从外部将 4}ii 限控制
在 40% 到 100% 固定限流但之间。
TOPS"witch-FX 的 R DSC 0 1\ ) 1直较小，
为保持电源输出稳定
脉宽调 fuiJ 器根据流入控制号|脚的电流按比例
降低占空比。
当控制引脚的电流增加时，
比统性降低到最小占空比 DC M1No
在选择阻但时 i青
参见"典电性能特性"中的图表。
最小占空比和跳过周期
当电 i原输出负载 1成小时，
也·可通过连接在
←旷三r
U
工二
由于较大的
可选择功率居过
所需功率的 TOPSwitch丑Yj丰设低其流限值来获得
更高的效率。
通过连接在多功能脚和经整流的
在 iyfi 高压总线间的电阻提供少量前馈电流，
如果达到 DC M1N
后控制电流再增加 O .4 mA ，则脉宽调制器如 ftilJ 占
种特性在输出负载的消耗功率小于最小占空比
的 TOPSwitch-FX 所提供的功率时，
允许电源
以跳过周期模式工作。随负载的增减，
回@-YN，
O
。O
川剧的刷品也
空比以离散方式从 DC M1N 降至零(参见国 4 )。这
SWitching
Frequency
电 i原能
同
4 ms
树
在正常工作和跳过周期模式间根据需要自动转
换，
VDRAIN
无需其它控制。
在电源输出端连接一个最小负载，
保持占
空比始终高于 DC M1N ，就可以禁止跳过周期 O
图 6、
开关频率抖动
气
匾自liI宝y宝91
可实现真正的限制功率工作。在使用 RCD w 位
流高压总统|间的单电阻设定。电源接通后禁
电路的高反射电压的设计中，这种前馈技术能
用 UV ，使输入电压工作范围更宽。直到电源
降低高压线路上的最大茹位电压。流限比较器
失调并试图再次接通前都不再检测输入电
的问值采用温度补偿，这样可将输出
!主。过是通过仅在自动重启动电路中的除 8 的
MOSFET
的 RDS(ON) 随温度变化而引起的电流限制的变
计数器计满 (87) 时才接通 UV 比较器来实现的，
化;成至最小。
此时计数器也宣位到上电时的状态(见图 5) 。
前沿消隐电路使流限比较器在输 M08FET
从图 16 可见禁用 UV 特性与
OV 无关。
刚导通的一段很短的时间内不工作。前 m~肖阳、
时间是这样确定的:使初级端电容和次级端整
线路过压'关断 (OV)
流器反向恢复时间引起的电流尖峰脉冲不会引
起开关脉冲的提前结束。
用于 UV 的比电阻同时也用于设置过压
l' J 限，一旦且过此门限即强迫 TOPSwitch-FX
如图 33 所示，由于 M08FET 的动态特性，
前沿 i肖隐、后很短的一段时间内，电流限制可以
设得更低。为避免在正常工作使引起电流限
制，漏极电流的波形应在国示的箱形中。
线路欠压保护 (UV)
在上电时，
UV使 TOPSwitch-FX 在输入
电压到达欠压阀值前保持关断。在掉电时，
输出关 i析。从图 8 可见 OV和 UV 的比率预设
为 4.5 ，这使得整流的直流高压超过 OVI、 j 限
时关断 TOPSwitch-FX
的功率 MOSFET ，此时
山于漏极没有反射电压和漏电尖峰，经整
J祀的直流高压的波动能力增大到 M08FET 的
额定电压(
700V )
0
OVI、 I 限有少量滞后以
防止噪声引发关断。从图 15 可见禁周 OV特
性与 UV 无关。
UV 防止 TOPSwitch-FX在输出失调后自动重
启动。在待机电源等 J，!L 用中，它能防止关断
时由输入电容缓慢放电百IJ 产牛-的干扰。掉电
时的 UV 间值由连接在多功能脚和经整流的直
,
。scillator
(SAW)
DMAX
巾
n
-m
叫
EM
mP
i-
Time
PI-255ι092999
图 7 、同步时序图解
6
·皿盈盈~昼~
降低 DC MAX 的线路前债
内部放电到 4.8V 内部欠压门限( (控制弓|脚电容
设置 UV 和 OV 的此电阻同时也用于产生电
压前馈，从而使输出纹 i皮最低并降低电源、输出
对统路瞬时现象的敏感。这种前馈工作方式在
图 4 中以 1 M 的不同值表示。值得注意的是，对于
同样的控制剖脚，电 l五更高会使占空比更小。
为更安全起见，最大占空比也从电压略高于 UV
门限值时的 78%(
38%(
典型值)降至 OV r' J 限值时的
典型值) (见图 4 ，
8 )
0
OV !'J限值时 DC
MAX 为 38% 是为了确保 TOPSwitch-FX 的功率在 lE
47μF 时接近 32ms) ，则控制弓|脚进入滞后调节
模式。在此模式 1亨，控制l 弓 1 ，即在 4.8V到 5.8V 间
转换充电和放电周明(
~~上述控制!即工作原理
一节)并放完整个高压直流输入，
11..1.
rj] 耗很低
( 230VAC 多功能弓 l'即开路时典型值为
160mW)
ο
进入这种模式后 ，
TOPSwitch-FX如果被远程
打开，它将在控制l 弓|脚电压再一次达到 5.8V 时
开始执行正常的软启动程序。在 ßj 差情况下，
从远程开指令到启动的延迟挝多与控制脚的整
个充/放电周期时间相同，
常工作时不会受到这种特性的限制
~~ 47uF 控制Il却电容时
接近 125ms 。这种降低功耗的远程关模式开销
小，不会产生不可靠的内部机械开关。也可以
远程开/关和同步
用微处理器米控制j 接通和关断序列，在 l质率和
TOPSwitch-FX的开/关可通过控制流入或流出多
激光打印机等应用中常常使用这种方法。更多
能弓|脚的电流米接通或关断，这使得很容易
信息请参考应用举例后的图 270
通过儿种方式实现的 TOPSwitch-FX远程控制。
把二极管或光调器的输出连接到多功能引!郎和!
源极弓 11即可以"启动"这一功能(国 19
) ;连
接到多功能号!脚和控制弓|脚可使此功能"取
消"
(图 20)
启动 10ms (典型值)后，启动片内的软启
动功能。最大占空比在此 1
Oms Jl:Jj I同从零钱性增
加到最大缺省值 78% 。除启动时外，软启动在
多功能弓|脚接收到 OV 、
UV和远程开/关等
弓|脚功能产生的禁止输出信号'时 ，
TOPSwitch-
FX完成当前开关周期后强制关断输出，如图 7
所示。内部振荡器在当前周明结束前轻轻停
顿，直到禁止信号结束 O
软启动
当多功能寻|脚上的信
号从禁止变为允许时，内部振荡器开始 F 一个
开关周刑。采用这种方法 ，
每一次重启动时也会被激活，包括自动重启动
和远程关断或热关断后，控制号 1 ，因电压(
Vc )
进入滞后调节的重启动。这能使输出 MOSFET
f否位电路和输出整流器在启动时的电流和电
压压力降至最低。
关断 l 重启动
TOPSwitch-FXJffJ. 过
此弓|脚能与任何频率低于内部开关频率的外部
信号同步。
为使 TO P Switch-FX 在故障情况下的功耗
最小，关断/重启动电路在输出尖调情况下，
一般按 4% 的自动重启动占空比接通和断开电
如上所述，远程开/关特性使 TOPSwitch-FX能适
周期接通/关断而延迟很小。远程开/关功能通
常被用作关断 TOPSwitch-FX的备用或电源开
关，使之极长时间内处于极低功耗状态。如果
处于远程关断状态的时间过长，能使控制弓|脚
源。失调不仅中断外部流入控制脚的电~t: ,
Vc
调节也从分流模式进入前面介绍过的滞后自动
重启动模式。当故障情况去除，电源输出稳定
后 ， V c 调节又转回到分;在模式，电源又恢复正
常工作。
7
··臣"埠'.oi悔~.&.oi四-
滞后的过热保护
关频率较低，如对噪声敏感的视频应用，这
TOPSwitch.♂X 由精密的模 f拟以电路提供温
时可通过将频率弓!脚与控制引脚短接来边佯
度保护。当输出 MOSFET 的结温 Jß 过热关断温
减半的开关频率 65kHz(
度(典型值 135 C )时，该电路就关断输出
所示电路可将待机模式时的开关频率从固定
0
MOSFET 。当结温冷却到低于滞后温度时，器
件恢复正常工作。此芯片采用 70 C 较大的滞后
0
的 130kHz 降为 65kHz ，使电源功耗最低。
运用多功能弓!脚 (M)
值，可以防止反复故障情况下 PCB 板过热。当
电洒、关断后， V c 的调节进入滞后模式，控制脚
上的波形为 4.8V 到 5.8V 间(典型值)的锯齿波。
因 11 )。另外，图 12
电流注入多功能习|脚时，它相当于最大
电流 +400uA (典型值)的 2.6V左右的电压源。
在 +400uA 时，这条号|脚转为吸收恒定电流。
电流从多功能弓|脚流出时，它相当于最大电
带隙基准
流 -240uA( 典型值)的 1.32V左右的电压源。在
TOPSwitch-FX 内部所有的关键电压均得自
于一个具有温度补偿的带隙基准 o
此基准电压
240uA 时，这条 SI 脚转为恒定电流源。请参见
图 9。
用多功能斗|脚能提供的功能共五种:
还用于产生一个具有温度补偿的电流基准，经
OV 、
调整后，此电流基准能精确设定开关频率、
MOSFET 门极驱动电流、流限和线路过压/欠!五
门限。
TOPSwitch-FX 改善了电路性能，使以上
UV 、降低 DC MAX 的自ÎJ 馈、外部流限丰rl 远程
开/关 o
短路多功能习|脚和 ìJ~ 极 sl 脚可以禁用
这五种功能，迫使 TOPSwitch-FX 以 TOPSwitch- 1I
一样的三端模式工作。通常在多功能 ~JI 脚和
这些重要参数的稳定性更高，相对于温度的容
整流的高压直流总线间连接→个电阻，用于
差更严格.
恰 ìwj 输入电压，并且实现 OV 、
UV和降低 DC MAX
的前馈功能。在此模式下，电阻值确定 OV/UV
高压偏置电流源
电压门限值，而且 DC MAX 从整形盲流高「巨刚超
在启动或滞后模式工作时，高压电流泪从
漏极引脚输入，为 TOPSwitch 器件提供偏置，并
对控制脚的外接电容 (C T ) 充电。在自动重启动
、远程关断和过热关断输出时，器件进入滞后
工作模式。此时电流源通断的有效占雪比约为
过 uv 门限值时开始统性降低。在高效率应用
中，此引脚也可用于外部 ~L 限模式，将此引
脚通过一个电阻连接到源极号|脚上，从外部
将流限值降低到接近峰值电流。在这两种模
式中，此弓!脚都可用于远程开/关和同步的输
入。表 2 是这些功能可能的组合，图 13 到 23 是
35% ，此占空地由控制脚充电 (I c)和放电电流 (I CD
电路学例。根据多功能弓 i 脚 I/V特性曲线对具
1 和 I CD2 ) 的比率决定。正常工作情况下，输出
体函数的描述如图 8 所示。横轴正极方向 51 示
MO
注入多功能弓|脚的电流，纵轴根据不同功能
SFET接通，此电流洒、关断。
代表不同的涵义。对于控制输出开/关的 UV 、
频率弓|脚和多功能弓|脚的使用
OV和远程开/关，纵轴代表输出的允许/禁止状
态。电流 luv( 典型值 +50uA )触发 UV ，
运用频率弓i 脚 (F)
型值 +50uA )触发 OV 。降低 DC MAX 的电压前馈
将最大占空比从 IM(DC/
频率寻|脚是一条数字输入弓|脚，仅限
TO-220 封装提供。频率引脚与源、极弓|脚短路
时选择了固定的开关频率 130kHz(
图 10 ) ，适
合于大多数应用。另外一些应用可能希望开
8
lov( 典
典型值 +90uA )时的 78%
降低为 Iov (典型伯 +225uA )时的 38% 。只有当
多功能弓|脚电流为负值时才能使用外部流
限。流限编程范围和如何选择恰当的阻值请
参见典型特性章节中的图示。
·四盗盈盈宝~
多功能弓|脚表
插图编号'
J3
一端工作
J
14
15
欠压
J
J
过压
J
输入前馈 (DC MAX )
J
输入前馈( IU MlT
16
17
18
19
20
23
J
~
i~
~
J
)
~
外部流限
~
J
远程开/关
J
~
~
~
~
~
此表格仅仅列举 f 多功能引脚可能采用的多种配置的一部分。
表 2 典型的多功能寻|脚配置
IREM(N)
l:lV
luv
(Enabled)
Output
MOSFET
Switching
lM
\J
lfd i
(Disabled)
←『卢---t
'
1 \VD 础 ledwh卢 s啊Iy
1M
regulation
ILl M1T (Delault)
Current
Li mit
'
1M
DC MAX (78 .5%)
Maximum
Duty Cycle
lliljl 二l
,
"
1M
VBG + VTP
MULTIFUNCTION
Pin Vo~age
VBG
-250
-200
-150
-100
-50
0
50
100
150
200
250
300
350
4∞
1M
MULTI-FUNCTION Pin Current (μA)
Note: "j" his ligure provides idealized lunctional characteristics 01 the MUL TI-FUNCTION pin with typi饲 I pe厅'ormance values
Please reler to the parametric table and typical pe厅ormance characteristics sections 01 the data sheet lor measured data
同 2524， 081999
图 8 、多功能号|脚特性
9
匾血lil室主叠室主E
CONTROL Pin
TOPSwitch-FX
....(NegaJive Current~e~se- ON/OFF ,
Current Limit Adjustment)
~VBG +V丁
MUL TI-FUNCTION Pin
….
(Positi~e
Current Se~?e : Unde..r: -Voltage ,
Over-V.o ltage Maximum Duty
Cydé Reduction)
.L
.……………… …………………………………………………………………………
E
。 1-2548-092399
因 9 、多功能 SI 脚输入简因
频率弓|脚的典塑使用方法
O
O
+
+
DC
DC
Input
Voltage
Input
Voltage
PI-25 口 6-081199
口 1-2505-08 才 199
因 10 、全频率工作 (130kHz)
图 11 、二|二频率工作 (65
O
+
Qs can be an optocoupler output
DC
Input
Voltage
STANDBY
PI-2507-080699
图 12 、半频率待机模式(玫率待机可以更高)
10
kHz)
匾圄量宝~室主E
多功能弓|脚的典塑使用方法
。
+
+
V uv = luv X R LS
V ov = lov X R LS
For R LS = 2M\)
V uv = 100 VDC
V ov =450 VDC
DC
Input
DC
Input
Voltage
Voltage
DC MAX @100VDC = 78%
DC MAX @375 VDC = 47%
PI-2509-081 才 99
PI-2508-081199
图 13 、三端工作(禁止多功能特性。
图才 4 、实现欠压、过压和降低最大占
空比的线路检测Ij
频率弓 11即与源极或控制极弓 l 脚
相连)
+
+
2MQ
IR LS
DC
Input
Voltage
V uv = R LS X luv
V ov = lov X RLS
For Value Shown
V uv =100VDC
For Values Shown
V ov = 450 VDC
DC
Input
Voltage
22KQ I
IN4148
6.2 V
同 -2515-081 才 99
PI-25 1O口 811 四
图 15 、仅实现欠压的线路检测(禁止过压)
因 16 、仅实现过斥的线路检测(禁止欠 Æ)
,
。
+
+
For R 1L = 12 KQ
I UM1T = 67%
I Ll M1 了 = 90% @ 100 VDC
ILl M1T = 55% @ 300 VDC
For R1L = 25 KQ
IUMIT = 40%
DC
Input
Voltage
See graph for other
resistor values (R ILl
DC
Input
Voltage
R 1L
R1L
PI-2517 口 81199
图 17 、外部设定流限
PI-2518-081199
图 18 、流限随电 JE 降低而降低
11
·皿量宝Z壶宝~
多功能弓i 脚的典塑使用方法
O
O
+
+
OR can be an optocoupler
output or can be replaced
by a manual switch ,
OR can be an optocoupler
output or can be replaced by
a manual switch
DC
ON/OFF
Input
Voltage
DC
Input
Voltage
ON/OFF
间 .2522.081 才 99
PI.2519-081 才 9日
图 20 、取 j肖远程开/关
图 19 、启动(叮靠的)远程开/关
O
O
+
+
OR can be an optocoupler
output or can be replaced
by a manual switch
For R 1L
=12 KQ
=67 %
ILl M1T
DC
Input
Voltage
OR can be an optocoupler
output or can be replaced
by a manual switch
DC
Input
Voltage
For R 'L = 25 KQ
ILl M1T = 40 %
24K (l
R MC
=2R 1L
R"
ON/OFF
PI.2520-081 句 9"
PI.2521.081199
因 21 、用外部设定限流启动远程开/关
图 22 、用外部设定限流取消远程开/关
,
+
RLS~2MQ
DC
Input
Voltage
OR can be an optocoupler
output or can be replaced
by a manual switch
一
ON/OFF
For RL5 = 2M (l
V uv = 100VDC
V ov = 450 VDC
PI.2523-081199
图 23 、用线路检测取消远程开/关
12
-.l!l.iI宝y室主E
应用举例
RCD1在位电路(
R3 , C3 和 D 1 ) ，通过足够
余址，将最差条件 t.; TOPSwitch-FX 的漏极
高效的 30 瓦特通用电源
电压限定在安全范罔内。
国 24 所/)\电路利用 TOPSwitch-FX 的某
增大
TOPSwitch-FX
f 最大占空比(确保至少 75% ，而
些特性降低系统成本，减小电源尺寸，提
TOPSwitch- 1I 的为 64%) ，因而可以使用更
高效率。此设计提供 12V 、
小的输入电容 (C1 )。随 RCDll在位而来的最大
30W输出，采用
i且用的 85V 到 265V 交流轴入，在 50 C 内以 }f
d 空比增大和高反射电压{吏 T1 的初次级匣
架方式工作 c
敖比较大，降低次级整流管 D8 上的峰值反
0
使用 TOP234 时满载额定效率
口l 达 80% ，
而J I l!.庄。因此，
通过电 IIfL R 丁和 R2 从外部设定的
TOPSwitch-FX 的流限{]'I 1又略高于低电 )f 工
作时的昨值 Ft!. ì杠，约为固定限流值的 70%
时比，对设定的输出电压，可以采用更
小的变!七器磁芯和/!iJ..允许变压器初级电忠、
豆豆高，降低了OPSwitch-FX 功耗，同时避免
15V 以「输出使用肖特基二
极管整流器，会极大地改善电源效率。
TO
PSwitch-FXfrJ 跳过周期特性使电源在空
载调节时无需!韭负载，降低[ I l!.源的空载/
待机功柱。频率抖动特性能使传导 EMI 的卢布
空符合 CISPR22 ( FCCB )标准。
~l!.路采用简单的开纳感应电路米降低
启动和输出瞬态情况下变压器磁芯饱和。
成水。输出电压出齐纳二极管(
电阻 R1 捉供电 Ui 前馈信号，降低流限，提
反元桐台器(
高电压，以限定高输入电!长情况的最大过
也阻 R8 捉性进入开纳二极管的偏置电流?产
战功率。前 i费功能与
r J才带的软启动功能归
结合，可以用 J/. EH 电压较高的低成本的
R2 )电压
U2 )和电阻 R6 上的同降决定，
生对 12V 输出电平、过!王过载和元 {'I二变化时
:t 5% 的稳定度。
C3
4.7 nF
1KV
RTN
R1
4.7MD
1í2W
R8
150 D
C1
68
U2
ltF 呵、
: LTV817A
400V )
U1
TOP234Y
VR2
1N5240C
10 V, 2%
PI-2525-0823g9
国 24 、使用外部限流的 30W 电源
13
匾圄噩噩噩室主E
35 瓦特多组输出的电源
设计:ìi:利用软启动手fl 较尚
图 12 所呆的 35Wlî.陆输出次级陆在的电
iif;( 利用 TOP223 实现多输出，
DVD 等应用巾。
VCR 、
交流 230V ，
可用于机 JDf 盆、
所示 r b，赂的设计输入为
陀来 l)，~ IJ 、变压器尺寸 J
进冲电路(
I议
在采用 100fJj(; 115V 交流仅极输入
另外，
时，
也能提供 35Wì指战功字输出。
l
100V )、
过压关断(
DC MAX 的[毡「王的 i贵特忏 c
如~
i果扩1
lîffJ
i果车命 LU 能
*断特性在白;7t[输入超过
瞬间关断。
ii!t
450V 时关出Î
TOPSwitch-F X. ìì'í I涂!乏与.j 1[1. fr 丰U i届
尖峰，
从而将 MOSFET 的制定扰电 illí 能与扩
大 flJ 700Vο
电
J.f
R9.
由于在乡村地区 r lJ.庄常 tH f见证长
;主持忡口 j 以防!l:.因此而王成的 I IJ. ì原 t~l
R10 i 门 R
'i' .
在对悦顺眼
一 tí~ 户;
3 月!才(果忏
3 才 ~0 补
采用 J.x 嗣 f7 器通过电阿l
33V 和 5V~fJtr 出 íl~ í1!此
Jt 'Ë
4 白出屯!五出变f!，措
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450V )和 1;平在t
lii
、{
什叶
用
检测(
ff 干扰电视接
吁 fr TOPSwitch-FX 与;原
字的的'但下肘;法
ú 丰、民iI
R1(2M Ç2)实现欠!王
;咸小，
通过的颇丰;吨'1'边顷，
厅由 3
用单一电!王采样屯 ßtt
‘
极 L.q 凹ì1}主的!际京 ';1 时改为与控制脚连接
在|述 E
TOPSwitch-FX的优础性体现在以 卡 JL
IY) r.~; HJ 中，
i牛顿卒特
Jj 二关 i皮 1巴 Lr'1 dv/d tLU
收的恬身、j 视频 l噪声减毛最小。
iH.也可提供且用输入的 25W额 Iflítr
山。
R4 , C4 )
[
E皿温室Z叠室主E
满载玫率超过 75% 。初级再位元件 VR1 和 01
弓|脚闸的|同距增大 f 漏电距离，在采用风
扇冷却和计算机电源等高污染环境中特别
将峰值漏极电压限定在安全范围内。
有用，
TOPSwitch-FX
的频率抖动特性也能降
低 EMI ，通过选择适当的 Y1 电容(
输入滤波器件(
CY1 )和
CX 1 , L 1 )使辐射值低于 CI
SPR22 ( FCCB )标准。为将 TOP223 的共模
暂态相合减至最小，
Y1 电容连接在直流正
极输入上，通过 275V MOV (RV1) 能实现 3KV
电容 C1 为高压直流电源提供高频去调
合，当直流源到此待机电路距离不长时无
需此电容。线路检测电阻 R1 实现直流输入
的欠!压检测。当交流关断时 ，
TOPSwitch-FX
的欠压关 l析特性防止山于主转换器中大存
储电容放电缓慢|而在输出端产生自动重启
防雷击装置。
动尖脉冲。当输入电压低于保持输出受控
17W 计算机待机电源
所需值时关断电源，直到输入电压高于欠
提供 3.3V 和 5V 次级输出和 15V 初级输出的
压门限(
V uv )时才重新接通电源。欠!五门
17W 计算机待机电源如图 26 所不，且中使用
限设定在 200VOC ，
的 TOP223 司采用 230VAC 或 100/115VAC 电压工
能节约分立元件吗基于的设计所需的若干
作，无需输入倍!五器。此设计利用
ch-FX
r
TOPSwit
软启动、欠压检测、严格的流限变化
和更高开关频率特性，例如l 开关频率更高问
时流限尘化更严格能允许使用 EE19tí结芯。另
外 ，
TOPSwitch-FX 高压漏极电压引!即和{压压
170VAC Bt启动。此特性
个实现瞬间关断功能的外国元件。
偏置绕组经 02 和 C6 整流和ìr.t ì皮后产牛一
TOP232 的偏置电压，并为主电源初级控制
电路提供 15V 初级偏置输出电压 o
R9 , R 怡
和 R11 通过如图所忌 TL431 ( U3 )电路检测
-l!l且也壶室主E
3.3V 和 5V 输出电压。电阻 R6 限制通过光润器 U2
在这种情况下，可以用简单的 RC 滤波器米产生
的电流并设定整个 AC 控制环路增益。电阻 R7
驱动 U4 的宣流电平信号(图 27 中未显示)。此
俯{果光惘合器在最小电流时 TL431 有足够的偏
远程接通特性方便计算机根据需要唤醒打印
'lf. r且流 O
机、扫描仪、外部调制解调器、磁盘驱动器等
电容 C8 提供软启动功能，消除 f 接通
电源时的过冲。
TO PSwitch-FX 的空载调节(跳过
间明)特性使电路能满足 PC 机的 BlueAngel标准对
外 ì~ 0
为 f 节电，外设通常设计为-段时间没
行使用后自动关断。
吁机电源的低功耗要求。
除 f 能使元件数最少 ，
TOPSwítch-FX在
以下应用中还具 {J 许多技术优势:
处理器控制电源开关
1
山 ri止于 j!1程关断模式时几乎不消耗能
{i二 i者如打印机等应用中，可能需要在做处理器
号c ，
甜控制 f ，用廉价的瞬时接触开关来实现
的电沈
TOPSwitch-FX
式功琵特别低
的电源开关。低功耗远程关断特
性可以用很少几个外围兀件实现此功能，如国
27fi斤示。只要按钮式瞬时接触开关 P1 被用户归j
M 脚 JF 路) , TOPSwítch-FX 的关断模
VACp ，t 为 160mW
2
fT ，光调 U3 被启动并通知微处理器。最初当电
;原关断时(
I币外部电路也不消耗高压直流总统上
110VACot 通常为 80mW ，
230
c
可以使用曦价的、低电压/电流的瞬时接触
开关=
Mt即悬空) ，闲合 P1 将通过二极宫'
(1&程)使
TOPSwitch-FX 的 M 弓 1)郎和源极弓 I !.出l
3
瞬时挂触开关无需去抖动电路。在接通用
k 拔，挂通电源。当次级输出电压 VCCt耸立
间，电泊的启动时间(通常 10 到 20ms )与
后，微处理器被启动，通过由光鹊 U3 输出驱动
民处理器拍初始化时间起去抖动滤泣器的
的开关状态输入得知 P1 己闭合，此时它通过光
作用，保证只有当开关被按下至少达到伫
桐 U4 发出使电视;保持接通状态的控制信号 G
述时间才允许挂通。在关断阴间，微 Y.HfJl.
如
器在检测到开关的第→次闭合时开始关 l析
日:用户再次按下开关 P1 发出关断命令，微处理
杠序，尔后的开关反弹则不超作用。如果
;窑通过光捐 U3 检测到此信号后启动产品特定的
关断程序。例如在喷墨打印机中，关断程序可
有必要，微处理器可以用软实现关断时的
r f[l头安全地停在存储位置。在带有
开关去抖动，或用洁、波电容作为开关状态
能包括将 f
也盘驱动的产品中，关断程序可能包括将数据
输入。
现设置存储到磁'盘上。当关断程序结束，电源、， 4
由于 M 号|脚电流提供内部流限，光制 U4 输出
被安全关断后，微处理器通过将光棉 U4 关断来
工作无需外部流限电路。
H 放 M 弓|脚。如果子动开关和l 光棉 U3 ， U4 离 M
斗|凹的距离较远，则需要用一个电容 C M 来用防
5
元需用连接到输入直流电!五线的高压电阻
为初级的外部电路供电。甚至 U3 的 LED 电流
止在 M 号|脚开路时将噪卢调合到弓|脚中。
也可由控制引脚提供。这不仅节省 f 兀
电源也可遇过用逻辑信号驱动光捐台器
件，简 ít [电路布局，还消除 f 开关状态
U4 的输入二极管，剧本地同域网!iX:串仁l /Jt 口
米远程技通。有时通过电站传送
J 系列逻辑脉
冲(例如山电缆的交流隅合)作为启动 1iJ" ~~比
直流逻辑电平更容均实现。
时出高压电阻引起的功率损耗。
6
坚固耐用的设计:不含有会被瞬态;在扑触
发的开关门问，而是山次级端伯微处理器
使电 ìt9、保持接通状态
16
噩噩盟军E
VCC
(+5V)
+
EWE
au
lp
川、
、
「 YT「
pnEα
M
刷……
mb 町、
dah
eukg
High Voltage
DC Input
47 llF
PI~2561 才 01399
国 27 、采用微控制器远程开关
,
17
匾压且直撞盈盈~
应用中的关键考虑
TOPSwitch-FX 与
表 3 列主杀了
TOPSwitch- 1I对比
TOPSwitch-FX 与
TOPSwitch- 1I 的特点和性能差异 •
TOPSwitch-FX 的多项主rr
特性减少了对昂贵的分立兀件的需求，另外一些忡忡增强了设计的强度，可以节
约变压器和其立功率 JL 件的成本。
功能
软启动
TOPSwitc~1I
无
TOPSwitc~FX
插罔
优点
·限制启动期间的峰值 fl.!.流
10ms
和电门:对元件的压力
·节约了 i午多应用中用于软
,
启动的外田元件
• {吏输出过冲最小
外部流限
无
从 100%到 40%缺; 8, 17,
·变压器更小
省流限值可编程 l1821 ，
·玫率更高
22
, .在输出过载条件下的功率
限制更严恪
67%
民NlCIX
78%
·输入电容更小(动态m:
14
rUJ
更宦)
I
·功率更高( j 使用 VOR 更大
的 RCOffi 位电路时)
·可用自特基次级整流二极
音高效提供高达 15V输出
降低D4仙〈的电
无
78%到 38%
压前馈
:4, 8,
14, 23
·防止电压纹波
·增加瞬态和电涌电庄的承
受力
过压关断
无
单电阻叮编程
8, 14,
·增加线路电涌的电压的承
受力
16, 23
l 单电阻r:tJ 编程
欠!王检测'
5.8.14
·在电源关断时防止自动重
启动脉冲干扰
15,23
开关频率
11 ∞k陆土10%
130k陆土7%
10
·变压器更小
•
开关频率选择
无
65k陆i:7%
11. 12
1专导 EMJ 的基 i皮小于 150 k陆
·在视频应用中用 RC丰DRCO
缓冲器来降低噪声时损耗
(限 TO-220)
低
·使待机模式的效率更高
•
EMJ 更低(二次谐波低于
150 陆-tz
表 30
18
TOP-II 与 Ta> -FX 的比较
)
·且且直昼rIt室主E
功能
TOPSwitch-1I
频率抖动
无
TOPSwitch-FX
:t4 kHz@130 kHz
士2
周期跳过
无
优点
插图
6 , 28
·降低(专寻 EMI
kHz@130 kHz
DCM1N ( 1.5% )时
4
·零负载调节时无需虚
拟负载
·空载时低功耗
远程开/关
无
单晶体管或光相
8 , 19 ,
·快速开/关(逐周期)
接口或手动开关
20 ,21 ,
• fj 可j 与x:失效控制
22.23
·远程关状态功艳低
27
·防故|璋的启动控制
• )G 需嵌入昂贵的开关
转挽器
·可以用处理器控制开/
关
·可以通过本地局域网
或并口关断/唤醒外设
同步
无
单晶体管或光相
接口
·可与外部频率较低的
信号同步
·可根据需要开始新开
关周期
门问式
热关断
j带后 (700C~带后)
·能从热故障中白动恢
复
·滞后值较大，防止电
路板过热
:t 10%(@2 5 o c)
流限容差
-8%(OOCfU 100
,
:t7%( @2 5 o c)
·由于杏差更小，功率
0
-4%(OOC 到 100 C)
可提高 10%
。c)
封装
DIP
0.03 7" /0.94mm
0.137"/3 .48mm
·对由尘埃、残渣与其
的漏
SMD
0.037"/0.94mm
0.13 7" /3 .4 8mm
它污染物引起的屯弧
极漏
T0- 220
0.046"/1.17mm
0.068"/1.73mm
具有强大的抵抗力
0.045"/ 1.14mm
0.113"/2.87mm
·预成型号|脚，可接受
电
TOP-220 的
PCB 漏极漏电
(寻|脚预成型)
的容忍 PCB 布局有更大
漏电
·更易于符合安全规则(
ULNDE)
19
··血l.iI宝Z墨宝~
l主容差更严格，
TOPSwitch-FX设计考虑
V OR 可达 165V 。在连续
模式的设计中，通过将外部流限功能简化
选择恰当的 TOPSwitch-FX器件
为一项输入电压功能，
在应用中，我们应该根据所需的最大
输出功率、效率、散热约束和成本目标来
选择最适当的 TOPSwitch-FX，
由于可以选
(见图 18) ，
V OR 还可增大到 185V
RCDm 位比齐纳 m 位的效率更高
但设计需要更加仔细。
输出二极管
择外部降低流限，为满足需要更高效率或
散热条件很差的低功率应用的要求，可以
!五、输出电流和Jd.用的照条件(包括热吸
选用较大的 TOPSwitch-FX器件，均可提供
收、空气流通等)来确定。
所需的输出功率。当从 X 轴垂直移动时，
首先遇到的曲或是最小的、成本最低的器
件，而最后遇到的曲线是最大的、最适于
有妓提供所需的输出功率的
输出二极管的选择通常山峰值反向电
TOPSwitch-II
的 DC MAx 较高，只要变压器阿敬比恰当，
在高达才 5V 的输出电压上可使用 60V 肖特基
工极管获得更高效率(见图 24 ，一个使用 60V
肖持基输出二极管的 12V ，
器件。
TOPSwitch-FX
30W设计)
软启动
输入电容
输入电容应能提供 TOPS 协 itch-FX 转换
器所需的最小直流电压，以保持最低额定
输入电压和最大输出功率条件下电压受控
由于 TOPSwitch-FX 的 DC MAx 比 TOPSwitch11 的高，它可以使用更小的输入电容。对而
言，只要变压器设计得当，通用输入的电
通常在启动时，电源在反馈回路稳定
前承受的压力最重。接通时，片内耳大-启动
在 10ms 内使占空比从零钱性增大到固定的
DC MAx '
使初级电流和输出电 J.E 依次上升，
为反馈回路控制占空比提供时间。这不仅
降低 [
TOPSwitch-FX MOSFET 、筒位电路和
输出二极营的压力，也有助于防止变压器
容通常只需每瓦 2IJF 。
在启动期间过饱和。软启动同时还能限制
初级箱位和输出反射电压 V OR
输出电压过冲的数值，在大多数应用中都
初级路位电路限制 TOPSwitch-FX的峰
值漏极电压。元纳 m 位(如图 26 中 VR1
)
无需软结束电容.
守 EMI 一电磁干扰
所需元件数少，所占电路板面积也较小 o
为提高效率，结位齐纳管的电压至少应是
输出反射电压的 1.5 倍，以缩短漏电尖峰的
传导时间。在通用输入应用中使用开纳哥
位，
V OR 的值最好小于 135V ，以适应齐纳管
的绝对容差和随温度变动的特性。这样既
能确保 m 位电路有效工作，也使最大漏极
电压低于 TOPSwitch-FX的额定关断电压。
要完全发挥 DC MAx 范围更宽的优势，
V OR 必须更高 ，
20
RCDr奋位比开纳错位的结位
频率抖动特性是将开关频率调制在狭
窄的波段内，从而降低与基本开关频率的
各次谐波相关的 EMI 峰值。此特性对均值检
测模式特别有利。从图 28 我们可以看出，
由于频率偏离增大，开关谐波阶次越高，
抖动的益处就越明显。
通过 FREQUENCY 弓|脚可以选择 TOPSwi
tch-FX 的开关频率为 130kHz 或 65kHz ，某些
应用为了降低高频辐射噪声，漏极节点需
匾圄量宝y空军E
12
电视札等军
飞
J
OVO 、
, i主 1叶选;学 65kHzT 作频率
f1 J 以降低结冲器 1tl 耗，
t.足高效率。
在全 JL wri 尺寸 jι 关紧雯的应用中，
提高过来。
Hz 也能降低 EMI ，
~ ì欠 i皆{皮。H民于 150kHz ，
z(YJ
同样，
边择 65k
可以看到 65kH
而频率在 150k
Hz 以 L 时 EMI 指妇、要求全严恪得多。
6
4
Quasi-Peak
2
阳-
对 10W
n川
时
O
用简单的电感就可以满足全世
3c
AU
|而无需更昂贵
4th
nunE UHa'' m
。
QUW av--
h
界?斗 f中关于 EMI 的限 ftjlj 圭件，
4ino
nu
?ι
以干 J.:L 肘，
监视器
(∞它}E。zu33ωα02。2
ltj1 G'i ( 例如iVCR 、
安较大的
nH
c
5th
(a) 月二关谐 i皮
的交流输入共柏扼试图。
。。
@OFa‘
y阿
-刷刷A
，
80
变压器设计
一一一…斗 TOPSwitch- J/
70
变 11，器的 T 11"陆通密度最好不屈 H30
(no
60
(
00 南斯，
后大流限时的峰值磁通密度不起
>
50
::t
m
40
它
)
过 4200 ri，)其斤。
同去~比的选择山能满足以下
ω
30
3
2
!之身、J ~也 11 ，
条件:
不超过 135V ，
( VOR
)在使用开纳 1在位时
使用 RCOm 位时不超过 165 ，
噜J
c. 20
~ -10
使用说ilít~ 古íJ t贵的 RCO 距拉时不屈过 185V
自 10
-20
0.15
如果设计的工作电流 ci 边低于固定的
ìílt:
~~ 1旺，
t!"
宁、
飞、
'2
HU
、
ii
)
在大多敬!占用中，
0
lt. TOPSwitch-ll 'E
TOPSwitch-FX
)"":恪的流限容;兰、
开关 l顷采和特白的软启动特性，
10
30
(b) 频率 (MHz)
!Jt!.
@opqh响
h叩-a
。。
图 17
30
Frequency (MHz)
品好用接近峰值工，作电 iyfi 的外部
降低峰1n昭通密度和峰值功率(
才O
80
更高的
都有助于
60
>
50
::t
m
减小变压器尺寸。
"0
,
40
ω
3
30
,-Ec.
20
2
待机功耗
<t -10
跳过时用特性能显著降低空载工7J 耗，
特别足在使用齐纳 ffi 位时。
如果次级 rjJ 耗
{良低，
叮以使用 TL431 调节器米控制l 反馈。
另外，
从 130kHz 正常开关频率降至 65kHz轻
载条件下的开关频率，
损耗。
O
也能显著降低开关
-10
-20
0.15
Frequency (MHz)
(C) 频率 (MHz)
图 28 、
(a) 用抖动降低了由低频 itf;皮引起的噪声
(b)
TOPSwitch- 1I整个范围内的 EMI 扫
视 (100kHz ，无抖动)，
(c) 间半电路和条
件下 TOPSwitch-FX 尝个范围内仨 MI 扫视
(才 30kHz ，背抖动)
21
-.l!l.iI宝m且E
Maximize hatched copper
areas (区:za) for 叩timum
heat sinking
+
HV
TOPVIEW
PI-2543-092199
图 29 、
DIP 或 SMD 封装 TOPSwitch-FX 的推荐布局连线方案(采用线路检测防
止低压和过压)
Maximize hatched copper
areas (医:z1 ) for optimum
heat sinking
HV
TOPVIEW
PI-2544'(国2199
图 30ι、
22
TO-220 封装 TOPSw
川it比
ch干.平X 的推荐布局连线方案(用线电压降低流限)
匾亘!lil蛙壶室主E
TOPSwitch-FX 的布局考虑
快速设计核查表
在进行电源、设计时，所有 TOPSwitch-FX的
初级端连接
TOPSwitch-FX 源极号|脚的输入 ~l皮屯
容的负极端采用单点连接到偏置绕组回路，
使屯涌电流从偏置绕组直接返回输入滤 i皮电
容，增强了电涌的承受力。
设计校验均应在工作台上进行，以确保在革坏
条件下不超过元件指标。器件品少应经过以下
测试:
最大漏极电 Lli 一检验峰但最高输入电压和
1.
最大过载输出功率情况 f , VDS 足否扭过
控制引脚旁路电容应尽可能接近源极和
675V 。当输出过载到电 i原即将 ili 入自动重
控制号|脚，其洒、极连线上不应有电源 MOSFET
启动状态(失控)刑的功率即品大过载输
的开关电流流过。
出功率。
所有以源极为参考、连接到多功能弓 1 )因
I二的兀件同样也应尽可能在近源极和多功能
最大漏极电流一在最高环境温度、最高输
2
入电压和1 最大输出负载情况 f ，观察启动
弓|脚，而且单独连接到源、极弓|脚。多功能弓 i
时的漏极电流 i皮形，检验是否出现变压器
脚的连线应尽可能短，并且远离漏极连线以
坦和的征兆和过多的前 ìfj 电流尖峰 O
防止噪声锅台。线路检测电阻(图 29 和 30 中的
TOPSwitch-FX 的前沿消阳、|间为 200ns ，可以
R1) 应接近多功能号|脚，使多功能弓 11即端的连
防止接通用用过早地终止叫在 200ns~肖隐时
结长度最短。
间结束前，观察漏极电流 j皮彤，枪验前 iE
用一个高频旁路电容与 47μF 的控制!即电
电流是否在允许的 iffi 限范围内(见
容并联使用，能更好地预防噪卢。反馈'光锅
图 33 )。
合器的输出也应接近 TO P Switch-FX的控
制和源极号|脚 O
#.在检查一在最大输出功率、品小输入电压
3
和最高环境温度条件下，检验 TOPSwitch-FX
y- 电容
压器、输出二极管丰rl 输出容温度指标。为
f 能按数据于册上的规定变更 TOPSwitch-FX
y- 电容的位置应接近变 J-E:贵的次级输出回
的 R DSC ON) ，够的国变空间 O
路号|脚和初级直流输入引脚。
此温度空间既
可以通过容差计算得出:也可以解释为将
主要吸收
,
一个外部电阻与漏极弓|脚串联，使用相同
的散热装置，得到的一个电阻值，它等放
Y 型封装 (TO-220) 的号!脚与源极弓!脚采
于在测试和最坏条件最大指标情况 F ，
用内部电连接。为避免循环电流，在引脚上
得器件的 Rosc
附加的散热装置不应与电路板上任何点电气
连接。
使用 P(DIP-8) 刑或 G(SMD-8) 型封装时，
另外，输出二极管的正负极号!脚下的铜片
面积应足够大，以利于器件散热.
，的差异。
设计工具
l.技术文献:数据手册，应用手册，设计思
想等等
器件下靠近源极寻|脚的铜片区域可起有效的
散热作用 o
ON
ìWIJ
2.
变压器设计电子数据农恪
3.
工程原型板 Power Integration 司 ι的网站
M w.powerint.com 上提供设计工具的最新信息.
23
·tru量室主墨宝~
产品指'标和测试条件
额定最大值 1
国 0.3 至IJ 700V
漏极电压
漏极峰值电流
存储温度
lt
0
-65 到 125 C
0.8A
止:
r，占 i晶 2
-40 flJ 150 oC
TOP233
1. 6A
号!钱温度 3
260 0 C
TOP234
2 .4 A
TOP232
控制脚电压
-0.3V 到 9V
控制脚电流
100mA
洼洼
l. f斤有的~门;生以 T-\ 二 25
多功能脚电压
-0.31 IJ 9V
2.
多功能脚也压
-0.3 到 9 飞Y
3. 只能用 116" 焊接 5 秒。
JÆ
白受内部电路限制。
热阻抗
热阻抗:
注意:
Y 封装:
(8 JA )1 一一一-
0
70 C/W
(OJC)2 一一一一 2 C/W
0
T
无须常 iZ 散 f，:飞片 O
2
在靠近型封表面或源极脚
的挝合烹川试。
2
3 焊在 0.36 干方英寸 (232mm ) 、 2盎同l
P/G 封装:
(610 克 1m2) 嗣皮上。
4 焊在 1 干方英寸 (645mm ) 、 2盎O'J
2
(8 JA ) 一一一_ 45 C1W
0
_
(OJC)5 一一
,
24
5 0 CIW
3
;
35 0 CIW 4
(610 克 1m2) 铜反上 C
5
在靠近型料表面的源极寻 l
剧P ðiH导 c
匾也l血昼Z叠室主E
条件(
除非主j 行说
明
参数
最小值
见图 34
符号
典型值 最大值
单位
树主口立 fiEt1E 一
一- -
源极 =ov;
40 至IJ 125
0
C
控制功能
频率习|脚
与ìI~极引
Ic=4mA
开关频率(平均
124
130
140
脚相连
kHz
fosc
值)
0
T)=25 C
频率习!脚
与;以极斗 l
3.8
5.0
6.2
脚相五
130k I-I z~ 作
频率抖动偏离
:t 4
M
kHz
65kHz-[
作
士 2
频率抖动调íI~J 率
最大占空比
250
DC MAX
IC=J CD1
,
IM~二 1 M 飞 DC)
75.0
78.0
82.0
1\1= 190μ 八
35 目。
47.0
57.0
0.8
1.5
2.7
-27
-22
-17
IIz
%
最小占空比(在跳
过周期前)
PWM 增益
,
DC M1N
Ic =4mA; TJ=25
Oc
%
%/
mA
%/
PWM 增益;虽飘
见 i主释 A
-0.01
mA/
。c
25
..臣"苗，暴~~暴壶-
条件(
除非另行说
明
参数
符号
见图 34
最小值
典型值
最大值
单位
1.2
1.9
2.8
mA
5.9
7.5
15
22
源极 =ov; 结温-0
40 到 125 C
控制功能(
外部基准电流
续
>
18
跳过周明开始时
见图 4
T j =25 0 C
的控制也流
Ic =4mA; T J=25 oC
动态阻抗
Zc
10
Ohms
见凶 32
动态阻抗温飘
0.18
% /oC
7
kHz
控制号|脚内部滤
波器极点
关断 I 自动重启动
控制脚充电电流
-5.0
-3.8
-2.6
Vc
=5V
-3.0
-1 9
-0.8
0
IC(CH)
T j =25 C
mA
见 if l'于 A
充电电流温 i票
白
Vc
=OV
o5
% /oC
5.8
V
i}J 重启动上限
VC(AR)
也压
自动重启动
F 限
4.5
4.8
0.8
1.0
2
4
5.1
V
电压
内动重启动滞后
电rE
,
自动重启动占空
V
8
%
lt
自动重启动频来
26
S1 开路
1.2
Hz
匾血1盖率y室主E
多功能输入
欠压门限电流
T j =25 0 C
luv
门限
欠压或远程开/关门
lov
54
210
225
240
10
;带后
i'
远程开/关负门限屯
IREM(N)
J ~R
-43
VM = Vc
VM = 0
300
400
520
正常模式
-300
240
-180
自动重启动模式
-110
-90
-70
2.00
2.60
3.00
1M
VM
IM(DC)
= 50 l-l A
1M
=
225μA
2.50
2.90
3.30
1M
=
-50μA
1.25
1.32
1.39
1.18
1.24
1.30
75
90
110
1M
降低最大占空比开始
-27
-7
i带后
IM(SC)
-35
T J=25 0 C
流和滞后
多功能寻 i 脚也压
50
T J=25 0 C
限电流和滞后
多功能习 II如短路电流
44
= - 150 I-l A
T j =25 0 C
的门限 l 包流
最大占空 tt 斜降
0.30 •
1M >IM(DC)
0.6
1 .1
1.0
1.8
1.5
2.5
4.0
1.5
2.5
4.0
见注释 B
1.0
2.9
V c- 1 .O
V F = Vc
10
22
40
多功能脚悬空
远程关断;届极电源电
V DRAIN = 150V
流
多功能脚知拨到
控制寻|月t~ 上
从远程接通到漏极接通
远程接通延时
T RON
见注释 B
,
i届极接且到禁止前的最短时间
远程关断建立时间
T ROFF
见注释 B
2
频率输入
频率号 II那门限电压
频率号 I !即输入电流
VF
27
-I!lil室m宝~
条件(除非另行说明)
参数
见图 14
符号
源极 =ov;
结温 =-40 到 125
0
段小值
典明值
0 .4 65
0.500
C
占主大
单位
值
电路保护
内部 ;d i/dt=
TOP232
T)=25 0C
白保护流限
I UM1T
1 OOmA/
μs
参见注释 C
内部 ;di/dt=200mA/
TOP233
T)=25 0C
μs
1.070
参见注释 C
内部 ;di/dt=300mA/
TOP234
T)=25 0C
μs
见图 33
主自入
T ,=25 0C
二 ç :，- AC
1.605
L一→-
A
整;在纹路
而 ilt 泊隐时间
t LEB
一一上
Ic=4mA
流限近迟
t lLo
Ic=4mA
输入
:MINi
ns
100
125
IC=4mA
热关断温度
075x
1Ll MIT
(MINì
0.6 x
A
?000
1.500
三二 85VAC
IINIT
o
193390
5i1
参见注释 C
主与沈找路
中开始流限
0.535
ns
135
。c
150
卜-一一→~
。c
K:~ 关断 i带日
七屯bL位门限屯
Ik
V C(RESE T)
~J34 ，
S1 开路
3.3
4.3
15.6
25 .7
7.8
12.9
5.2
18.0
30.0
9.0
15.0
输出
导通电 ~Iî
关断状态电流
击穿电压
r:
ROS(ON)
loss
BV oSS
;1 时间
,
T J=25 0C
TOP232
10=50mA
Tl= 才 OOoC
T =25 0C
TO P233
10=100mA
丁 =100
TO P234
10= 150mA
T ,=25 0C
T J=100 oC
,
0
C
V M 悬空 ， Ic=4mA
V oc =560V , T A=125 0C
V M 悬空 ，
10 =100 μA ，
Q
6.0
10.0
150
μA
Ic=4mA
700
V
T A=25 oC
在一个典巾的反激
式变换器中·测得 c
下降时间
V
100
ns
50
ns
电压供应特性
漏极电源电压
分路调节器电陀
V C(SHUNT)
参!Jt!.注释 C
36
I c =4mA
5.6
28
6.10
V
ppm/
。c
I C01
输出 MOSFET 导通
IC02
输出 MOSFET 关断
供/充电电
流
5.85
:t 50
分路调节器温 i票
控制脚提
V
mA
1 .1
··亘组监室Z壶宝~
注释=
A
对带有古1 号的技术指标，
负 ìM 度系敌对应于随温度增加其敬值增加，
日:温度系敌对
山 f 随温度增加其敖值减少 O
口水
,
a1.
,
证
丰疗 i
一事
'2
十1J
f
u日
B
生产时未经测试。
请参考典塑性能特性~ -Yî 中的图表(
iIi 限与外)'jj; ìfrE限电阻)
C
外部调节 m[ rí[~ 时，
D
TOPSwitch-FX 在漏极电压比 36V低 1~ 多的情况卡也可以启动和l 工作。
脚的充电电流会减少，
这会影响启动时间、
但是，
控制
自动重启动频率和自动是启动占空比。
请参阅低压工作特性曲线中控制脚充电电流(
Ic )与漏极电压之间的关系曲线。
t2
t
-F
二
t
一。 ι
D
41
DRAIN
VOLTAGE
才 0%
o V ---…-主----------PI.2口 39.口 43097
国 31 、
占全比的度量力;去
2100
}
咱圃，
巳
ω
』
80
‘"
60
」
。
c:::
40
。
20
•z
υ
1.2
自
1.1
志
』』
HCω
30z-《匠。
Z
a..
1.3
舌
E
g
u=
B2·OANON也
由白白F白DI
白白白Fl
一且
才 20
1.0
0.9
0.8
一」一 IINIT(MIN)
0.7
@ 85VAC
=里 IINIT(MIN) @ 265VAC
0.6
0.5
0 .4
0
- - IUMIT(MAX) @25 C
IUMIT(MIN) @ 25 oC
0.3
0 .2
O 才
O
O
2
4
6
8
CONTROL Pin Voltage (V)
才O
O
O
2
3
4
5
6
7
8
Time (us)
因 32 、控制脚的电流电压特性
图 33 、漏极操作时的电流
29
匾豆豆崖昼Z叠叠~
1;
470 n
5W
二三
V/
+lbp
RJV RD<U
寸 l飞
VA呻v
nuJ Qhv
O-'
40V
q
SG
>
<
O <U MK Q
470 n
。 -15
TOPSwitch-FX
V
NOTES: 1 This test circuit is not applicable for current limlt or output characteristic measurements
2. For P and G packages , short all SOURCE pins together
PI.2538.09169S
图 34 、 TOPSwitch FX 一般的测试电路
[在测试器件的电气特性时需要注意的问题
在电源外对 TOPSwitch-FX 单拙进行测
时的电源，控制脚振荡处于正确状态(漏极
试时，应该注意下面的问题。因 34 是对
工作的状;在)、从而观察到连续的漏极 j皮恨
TOPSwitch -FX 进行实验宝测试时建议使用
的可能性只有 125%
的电路图。
纯的漏极;皮恨，就应先将 V c 的电源电压力 1]
当 j届极电源加上时，器件处于自动重启动
状态。控制脚的电压将以一个低的频率在 4.8 到
5.8V 间振荡，而漏极则在控制制振荡的每个第
八周期导通。在此自动重启动状态 F 接通控制
因此如果坦、要观察到连
上，然后再把漏极的电源撞通。上述的 12.5%
的可能性是 111
8: 1 it.
放器造成的。可用临时
将拧制脚和源极号 l 凹坦路才￡复位 TOPSwitch-
FX ，
使之出现正确的状态。
典塑性能特征
,
<
·咱!::
E
」
咱z
圃，
ω
‘‘
2
υ
CURRENT Ll MIT VS. MUL TI-FUNCTION
PIN CURRENT
PI-2 5-4 0-0 91699
1.0
200
9
180
.8
160 古
7
忡。看
6
120
.5
100
E
刀
、‘.
4 1-
80
TOP233 1.00
TOP232 0.50
3
-250
-200
-150
-100
1M (1lÄ)
30
制
-50
'" 60
O
"'c
.巫且革矗立量室主E
CURRENT Ll MIT vs. 亡EXTERNAL
CURRENT Ll MIT RESISTANCE
PI.2539-091699
200
(《
)tE32ω』』20
180
8
160
7
?40
古
立
3
120 号
6
、‘
一-1
5
"0
100
4
3
O
10K
5K
15K
20K
25K
External Current Li mit Resistor
BREAKDOWN
VS.
TEMPERA TURE
~L
(0)
FREQUENCYvs.TEMPERATURE
n、。
Clf Lt可
。。
飞.嗡d
~
-g 1.0
~N
。三
它何
苦E
!1' 画
面三
0.9
Jl
啡。‘同。@n
。N
，F
，F
飞I
民-
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咱圃'‘、.
丁 2
(υ
Z)
。的
N 。#它ON--m』
E。
Aυcω=σ』
ωhH=S
』
h
。 H=
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。oa
-@寸m
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Notes:
1. Package dimensions conform to JEDEC specification
MS-001-AB (Issue B 7/85) for standard dual-in-line (DIP)
package with .300 inch row spacing.
2. Controlling dimensions are inches. Millimeter sizes are
shown in parentheses.
3. Dimensions shown do not include mold flash or other
protrusions. Mold flash or protrusions shall not exceed
.006 (.15) on any side.
4. Pin locations start with Pin 1, and continue counter-clockwise to Pin 8 when viewed from the top. The notch and/or
dimple are aidS in locating Pin 1. Pin 6 is omitted.
5. Minimum metal to metal spacing at the package body for
the omitted lead location is .137 inch (3.48 mm).
6. Lead width measured at package body.
7. Lead spacing measured with the leads constrained to be
perpendicular to plane T.
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1. Controlling dimensions are inches. Millimeter sizes are
shown in parentheses.
2. Dimensions shown do not include mold flash or other
protrusions. Mold flash or protrusions shall nol exceed
006 (.15) on any side.
3. Pin locations start with Pin 1, and continue counterclock wise to Pin 8 when viewed from the lop. Pin 6
is omitted.
4. Minimum metal 10 metal spacing at the package body
for the omitted lead location is .137 inch (3.48 mm).
5. Lead width measured at package body.
6. 0 and E are referenced datums on the package body.
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1. Controlling dimensions are inches. Millimeter 己
dirnensions are shown in parentheses.
2. Pin locations start with Pin 1, and continue 口口
Ir创丁1 left to right when viewed Irom the fron t.
Pins 2 and 6 are omitted.
3. Dimensions do not include mold flash or 巳
other protrusions. Mold flash or protrusions 口
shall not exceed .006 (.15mm) on any side. 巳
4. Minimum metal to metal spacing at the packJ
age body lor omitted pin locations is .068 日
inch (1.73 mm).
5. Position 01 the fonned leads to be rneasured [
at the mounting plane , .670 inch (17.02 mrn) 口口
below the hole center.
6. AII terminals are solder plated.
PI-2560-101599
,
35
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Power Integrations Inc
Headquarters
5245 Hellyer Avenue , San Jose , CA 95138 , US A. Main: (408) 414-9200
Website: www.powerin t. com
香港科汇(亚太)有限公司盈丰分部是 Power Integrations 公司唯→指定的牛
因和香港区代理商 O 所有经科汇公司购买的 IC ，→律得到 Power Integrations
公司的品质保证 O
香港科汇(亚太)有限公司盈丰分部中国各办事处:
!妇 L~
建国门北大街 8 号 fFi问大厦 1207 穿
电话
人民南路工段 18 号川信大厦 36 一(丁 -1 c主
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天日两路 218 母嘉里不夜城;江
电 i舌
应 3808-3809 4i 7~
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武汉市武再也;中南路 7 号中尚「场日阵 2406 字:
电 i古
中山南路 224 甘南京诺 ~W 商务火厦 3108 房间
电话
I皂话
电 lt
高新技术产业开发区科技路 26 号质检大厦 402 宗
电话
www.insight-ap.com
www.insight-ap.com.cn
Rev 2 , 3/01
36
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,
®
TOP232-234
®
TOPSwitch-FX
Family
Design Flexible, EcoSmart®, Integrated
Off-line Switcher
Product Highlights
Lower System Cost, High Design Flexibility
• Features eliminate or reduce cost of external components
• Fully integrated soft-start for minimum stress/overshoot
• Externally settable accurate current limit
• Wider duty cycle for more power, smaller input capacitor
• Line under-voltage (UV) detection: no turn off glitches
• Line overvoltage (OV) shutdown extends line surge limit
• Line feed forward with maximum duty cycle (DCMAX)
reduction rejects ripple and limits DCMAX at high line
• Single resistor sets OV/UV thresholds, DCMAX reduction
• Frequency jittering reduces EMI and EMI filtering costs
• Regulates to zero load without dummy loading
• 132 kHz frequency reduces transformer/power supply size
• Half frequency option for video applications
• Hysteretic thermal shutdown for automatic recovery
• Large thermal hysteresis prevents PC board overheating
• Standard packages with omitted pins for large creepage
• Active-on and active-off remote ON/OFF capability
• Synchronizable to a lower frequency
®
EcoSmart - Energy Efficient
• Cycle skipping reduces no-load consumption
• Reduced consumption in remote off mode
• Half frequency option for high efficiency standby
• Allows shutdown/wake-up via LAN/input port
Description
TOPSwitch-FX uses the proven TOPSwitch topology and cost
effectively integrates many new functions that reduce system
cost and, at the same time, improve design flexibility,
performance and energy efficiency. Like TOPSwitch, the high
voltage power MOSFET, PWM control, fault protection and
other control circuitry are all integrated onto a single CMOS
chip, but with two added terminals. The first one is a MULTIFUNCTION (M) pin, which implements programmable line
OV/UV shutdown and line feed forward/DCMAX reduction with
line voltage. The same pin can be used instead to externally set
an accurate current limit. In either case, this pin can also be used
for remote ON/OFF or to synchronize the oscillator to an
external, lower frequency signal. The second added terminal is
the FREQUENCY (F) pin and is available only in the Y
package. This pin provides the half frequency option when
connected to CONTROL (C) instead of SOURCE (S). The
features on the new pins can be disabled by shorting them to the
SOURCE, which allows the device to operate in a three terminal
+
DC
OUT
-
AC
IN
D
M
CONTROL
C
TOPSwitch-FX
S
F
PI-2503-073099
Figure 1. Typical Flyback Application.
OUTPUT POWER TABLE
230 VAC ±15%
PART
ORDER
Open
1
NUMBER3 Adapter
Frame2
TOP232P
TOP232G
85-265 VAC
Adapter1
Open
Frame2
9W
15 W
6.5 W
10 W
10 W
25 W
7W
15 W
13 W
25 W
9W
15 W
20 W
50 W
15 W
30 W
TOP234P
TOP234G
16 W
30 W
11 W
20 W
TOP234Y
30 W
75 W
20 W
45 W
TOP232Y
TOP233P
TOP233G
TOP233Y
Table 1. Notes: 1. Typical continuous power in a non-ventilated
enclosed adapter measured at 50 ˚C ambient. 2. Maximum practical
continuous power in an open frame design with adequate heat sinking,
measured at 50 ˚C ambient. See key applications section for detailed
conditions. 3. Packages: P: DIP-8B, G: SMD-8B, Y: TO-220-7B.
TOPSwitch mode, but with the following new transparent
features: soft-start, cycle skipping, 132 kHz switching frequency,
frequency jittering, wider DCMAX, hysteretic thermal shutdown
and larger creepage. In addition, all critical parameters such as
frequency, current limit, PWM gain, etc. have tighter temperature
and absolute tolerances compared to the TOPSwitch-II family.
Higher current limit accuracy and larger DCMAX, when combined
with other features allow for a 10% to 15% higher power
capability on the TOPSwitch-FX devices compared to equivalent
TOPSwitch-II devices for the same input/output conditions.
July 2001
TOP232-234
Section List
Pin Functional Description ......................................................................................................................................... 3
TOPSwitch-FX Family Functional Description ......................................................................................................... 4
CONTROL (C) Pin Operation ................................................................................................................................. 4
Oscillator and Switching Frequency ....................................................................................................................... 5
Pulse Width Modulator and Maximum Duty Cycle ................................................................................................. 5
Minimum Duty Cycle and Cycle Skipping ............................................................................................................... 6
Error Amplifier ......................................................................................................................................................... 6
On-chip Current Limit with External Programability ................................................................................................ 6
Line Under-Voltage Detection (UV) ........................................................................................................................ 6
Line Overvoltage Shutdown (OV) ........................................................................................................................... 7
Line Feed Forward with DCMAX Reduction .............................................................................................................. 7
Remote ON/OFF and Synchronization ................................................................................................................... 7
Soft-Start ................................................................................................................................................................ 8
Shutdown/Auto-Restart .......................................................................................................................................... 8
Hysteretic Over-Temperature Protection ................................................................................................................ 8
Bandgap Reference ................................................................................................................................................ 8
High-Voltage Bias Current Source .......................................................................................................................... 8
Using FREQUENCY and MULTI-FUNCTION Pins ..................................................................................................... 9
FREQUENCY (F) Pin Operation............................................................................................................................. 9
MULTI-FUNCTION (M) Pin Operation .................................................................................................................... 9
Typical Uses of FREQUENCY (F) Pin ...................................................................................................................... 11
Typical Uses of MULTI-FUNCTION (M) Pin ............................................................................................................. 12
Application Examples ............................................................................................................................................... 14
A High Efficiency, 30 W, Universal Input Power Supply ........................................................................................ 14
35 W Multiple Output Power Supply ..................................................................................................................... 15
17 W PC Standby Power Supply .......................................................................................................................... 16
Processor Controlled Supply Turn On/Off ............................................................................................................ 17
Key Application Considerations .............................................................................................................................. 19
TOPSwitch-FX vs. TOPSwitch-ll ........................................................................................................................... 19
TOPSwitch-FX Design Considerations ................................................................................................................. 20
TOPSwitch-FX Selection ................................................................................................................................ 20
Input Capacitor ............................................................................................................................................... 20
Primary Clamp and Output Reflected Voltage VOR ......................................................................................... 20
Output Diode .................................................................................................................................................. 21
Soft-Start ........................................................................................................................................................ 21
EMI ................................................................................................................................................................. 21
Transformer Design ........................................................................................................................................ 21
Standby Consumption .................................................................................................................................... 23
TOPSwitch-FX Layout Considerations ................................................................................................................. 23
Primary Side Connections .............................................................................................................................. 23
Y-Capacitor..................................................................................................................................................... 23
Heat Sinking ................................................................................................................................................... 23
Quick Design Checklist ......................................................................................................................................... 23
Design Tools ......................................................................................................................................................... 23
Product Specifications and Test Conditions .......................................................................................................... 24
Typical Performance Characteristics ...................................................................................................................... 30
Package Outlines ...................................................................................................................................................... 34
2
B
7/01
TOP232-234
DRAIN (D)
0
CONTROL (C)
VC
ZC
INTERNAL
SUPPLY
1
SHUNT REGULATOR/
ERROR AMPLIFIER
+
SOFT START
5.8 V
4.8 V
-
-
5.8 V
+
INTERNAL UV
COMPARATOR
IFB
VI (LIMIT)
CURRENT
LIMIT
ADJUST
+
SHUTDOWN/
AUTO-RESTART
VBG + VT
MULTIFUNCTION (M)
-
÷8
ON/OFF
CURRENT LIMIT
COMPARATOR
HYSTERETIC
THERMAL
SHUTDOWN
VBG
STOP
OV/UV
LINE
SENSE DCMAX
FREQUENCY (F)
(Y Package Only)
DCMAX
CONTROLLED
TURN-ON
GATE DRIVER
SOFTSTART
DMAX
CLOCK
HALF
FREQUENCY SAW
-
OSCILLATOR WITH JITTER
+
S
Q
R
Q
LEADING
EDGE
BLANKING
PWM
COMPARATOR
RE
SOURCE (S)
PI-2535-083099
Figure 2. Functional Block Diagram.
Pin Functional Description
DRAIN (D) Pin:
High voltage power MOSFET drain output. The internal startup bias current is drawn from this pin through a switched highvoltage current source. Internal current limit sense point for
drain current.
CONTROL (C) Pin:
Error amplifier and feedback current input pin for duty cycle
control. Internal shunt regulator connection to provide internal
bias current during normal operation. It is also used as the
connection point for the supply bypass and auto-restart/
compensation capacitor.
MULTI-FUNCTION (M) Pin:
Input pin for OV, UV, line feed forward with DCMAX reduction,
external set current limit, remote ON/OFF and synchronization.
A connection to SOURCE pin disables all functions on this pin
and makes TOPSwitch-FX operate in simple three terminal
mode (like TOPSwitch-II).
The switching frequency is internally set for 132 kHz only
operation in P and G packages.
SOURCE (S) Pin:
Output MOSFET source connection for high voltage power
return. Primary side control circuit common and reference point.
Tab Internally
Connected to SOURCE Pin
7D
5F
4S
3M
1C
Y Package (TO-220-7B)
M1
8S
S2
7S
S3
C4
FREQUENCY (F) Pin: (Y package only)
Input pin for selecting switching frequency: 132 kHz if connected
to SOURCE pin and 66 kHz if connected to CONTROL pin.
5D
P Package (DIP-8B)
G Package (SMD-8B)
PI-2501-031901
Figure 3. Pin Configuration.
B
7/01
3
TOP232-234
TOPSwitch-FX Family Functional Description
In addition to the three terminal TOPSwitch features, such as the
high voltage start-up, the cycle-by-cycle current limiting, loop
compensation circuitry, auto-restart, thermal shutdown, etc.,
the TOPSwitch-FX incorporates many additional functions that
reduce system cost, increase power supply performance and
design flexibility. A patented high voltage CMOS technology
allows both the high voltage power MOSFET and all the low
voltage control circuitry to be cost effectively integrated onto a
single monolithic chip.
Two terminals, FREQUENCY (available only in Y package)
and MULTI-FUNCTION, have been added to implement some
of the new functions. These terminals can be connected to the
SOURCE pin to operate the TOPSwitch-FX in a TOPSwitchlike three terminal mode. However, even in this three terminal
mode, the TOPSwitch-FX offers many new transparent features
that do not require any external components:
1. A fully integrated 10 ms soft-start reduces peak currents and
voltages during start-up and practically eliminates output
overshoot in most applications.
2. DCMAX of 78% allows smaller input storage capacitor, lower
input voltage requirement and/or higher power capability.
3. Cycle skipping at minimum pulse width achieves regulation
and very low power consumption at no load.
4. Higher switching frequency of 132 kHz reduces the
transformer size with no noticeable impact on EMI or on
high line efficiency.
5. Frequency jittering reduces EMI.
6. Hysteretic over-temperature shutdown ensures automatic
recovery from thermal fault. Large hysteresis prevents circuit
board overheating.
7. Packages with omitted pins and lead forming provide large
DRAIN creepage distance.
8. Tighter absolute tolerances and smaller temperature variations on switching frequency, current limit and PWM gain.
The MULTI-FUNCTION pin is usually used for line sensing by
connecting a resistor from this pin to the rectified DC high
voltage bus to implement line over-voltage (OV)/under-voltage
(UV) and line feed forward with DCMAX reduction. In this
mode, the value of the resistor determines the OV/UV thresholds
and the DCMAX is reduced linearly starting from a line voltage
above the under-voltage threshold. In high efficiency
applications, this pin can be used in the external current limit
mode instead, to reduce the current limit externally (to a value
4
B
7/01
Auto-restart
ICD1
IB
78
Duty Cycle (%)
Like TOPSwitch, TOPSwitch-FX is an integrated switched
mode power supply chip that converts a current at the control
input to a duty cycle at the open drain output of a high voltage
power MOSFET. During normal operation the duty cycle of the
power MOSFET decreases linearly with increasing CONTROL
pin current as shown in Figure 4.
Slope = PWM Gain
47
IM = 140 µA
IM < IM(DC)
1.5
IM = 190 µA
1.5 1.9
5.5 5.9
IC (mA)
PI-2504-072799
Figure 4. Relationship of Duty Cycle to CONTROL Pin Current.
close to the operating peak current), by connecting the pin to
SOURCE through a resistor. The same pin can also be used as
a remote ON/OFF and a synchronization input in both modes.
The FREQUENCY pin in the TO-220 package sets the switching
frequency to the default value of 132 kHz when connected to
SOURCE pin. A half frequency option can be chosen by
connecting this pin to CONTROL pin instead. Leaving this pin
open is not recommended.
CONTROL (C) Pin Operation
The CONTROL pin is a low impedance node that is capable of
receiving a combined supply and feedback current. During
normal operation, a shunt regulator is used to separate the
feedback signal from the supply current. CONTROL pin voltage
VC is the supply voltage for the control circuitry including the
MOSFET gate driver. An external bypass capacitor closely
connected between the CONTROL and SOURCE pins is
required to supply the instantaneous gate drive current. The
total amount of capacitance connected to this pin also sets the
auto-restart timing as well as control loop compensation.
When rectified DC high voltage is applied to the DRAIN pin
during start-up, the MOSFET is initially off, and the CONTROL
pin capacitor is charged through a switched high voltage current
source connected internally between the DRAIN and CONTROL
pins. When the CONTROL pin voltage V C reaches
approximately 5.8 V, the control circuitry is activated and the
soft-start begins. The soft-start circuit gradually increases the
duty cycle of the MOSFET from zero to the maximum value
over approximately 10 ms. If no external feedback/supply
current is fed into the CONTROL pin by the end of the soft-start,
the high voltage current source is turned off and the CONTROL
pin will start discharging in response to the supply current
drawn by the control circuitry. If the power supply is designed
properly, and no fault condition such as open loop or shorted
output exists, the feedback loop will close, providing external
TOP232-234
CONTROL pin current, before the CONTROL pin voltage has
had a chance to discharge to the lower threshold voltage of
approximately 4.8 V (internal supply under-voltage lockout
threshold). When the externally fed current charges the
CONTROL pin to the shunt regulator voltage of 5.8 V, current
in excess of the consumption of the chip is shunted to SOURCE
through resistor RE as shown in Figure 2. This current flowing
through RE controls the duty cycle of the power MOSFET to
provide closed loop regulation. The shunt regulator has a finite
low output impedance ZC that sets the gain of the error amplifier
when used in a primary feedback configuration. The dynamic
impedance ZC of the CONTROL pin together with the external
CONTROL pin capacitance sets the dominant pole for the
control loop.
Oscillator and Switching Frequency
The internal oscillator linearly charges and discharges an internal
capacitance between two voltage levels to create a sawtooth
waveform for the pulse width modulator. The oscillator sets the
pulse width modulator/current limit latch at the beginning of
each cycle.
The nominal switching frequency of 132 kHz was chosen to
minimize transformer size while keeping the fundamental EMI
frequency below 150 kHz. The FREQUENCY pin (available
only in TO-220 package), when shorted to the CONTROL pin,
lowers the switching frequency to 66 kHz (half frequency)
which may be preferable in some cases such as noise sensitive
video applications or a high efficiency standby mode. Otherwise,
the FREQUENCY pin should be connected to the SOURCE pin
for the default 132 kHz. Trimming of the current reference
improves oscillator frequency accuracy.
When a fault condition such as an open loop or shorted output
prevents the flow of an external current into the CONTROL pin,
the capacitor on the CONTROL pin discharges towards 4.8 V.
At 4.8 V auto-restart is activated which turns the output MOSFET
off and puts the control circuitry in a low current standby mode.
The high-voltage current source turns on and charges the
external capacitance again. A hysteretic internal supply undervoltage comparator keeps VC within a window of typically 4.8
to 5.8 V by turning the high-voltage current source on and off
as shown in Figure 5. The auto-restart circuit has a divide-by8 counter which prevents the output MOSFET from turning on
again until eight discharge/charge cycles have elapsed. This is
accomplished by enabling the output MOSFET only when the
divide-by-8 counter reaches full count (S7). The counter
effectively limits TOPSwitch-FX power dissipation by reducing
the auto-restart duty cycle to typically 4%. Auto-restart mode
continues until output voltage regulation is again achieved
through closure of the feedback loop.
To further reduce the EMI level, the switching frequency is
jittered (frequency modulated) by approximately ±4 kHz at
250 Hz (typical) rate as shown in Figure 6. Figure 28 shows the
typical improvement of EMI measurements with frequency
jitter.
Pulse Width Modulator and Maximum Duty Cycle
The pulse width modulator implements voltage mode control
by driving the output MOSFET with a duty cycle inversely
proportional to the current into the CONTROL pin that is in
excess of the internal supply current of the chip (see Figure 4).
The excess current is the feedback error signal that appears
across RE (see Figure 2). This signal is filtered by an RC
network with a typical corner frequency of 7 kHz to reduce the
effect of switching noise in the chip supply current generated by
~
~
~
~
VUV
~ ~
~
~
VLINE
~
~
~
~
0V
S6
S7
S0
S1
S2
S6
S0
S7
S1
S2
~
~
S2
S6
S7
S7
5.8 V
4.8 V
~
~
~
~
0V
S1
~
~
S0
~
~
S7
VC
~
~
VDRAIN
0V
VOUT
1
2
3
~
~
~
~
~
~
0V
2
Note: S0 through S7 are the output states of the auto-restart counter
4
PI-2545-082299
Figure 5. Typical Waveforms for (1) Power Up (2) Normal Operation (3) Auto-restart (4) Power Down .
B
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5
the MOSFET gate driver. The filtered error signal is compared
with the internal oscillator sawtooth waveform to generate the
duty cycle waveform. As the control current increases, the duty
cycle decreases. A clock signal from the oscillator sets a latch
which turns on the output MOSFET. The pulse width modulator
resets the latch, turning off the output MOSFET. Note that a
minimum current must be driven into the CONTROL pin
before the duty cycle begins to change.
PI-2550-092499
TOP232-234
136 kHz
Switching
Frequency
128 kHz
4 ms
VDRAIN
The maximum duty cycle, DCMAX, is set at a default maximum
value of 78% (typical). However, by connecting the MULTIFUNCTION pin to the rectified DC high voltage bus through a
resistor with appropriate value, the maximum duty cycle can be
made to decrease from 78% to 38% (typical) as shown in
Figure 8 when input line voltage increases (see line feed
forward with DCMAX reduction).
Minimum Duty Cycle and Cycle Skipping
To maintain power supply output regulation, the pulse width
modulator reduces duty cycle as the load at the power supply
output decreases. This reduction in duty cycle is proportional
to the current flowing into the CONTROL pin. As the
CONTROL pin current increases, the duty cycle reduces linearly
towards a minimum value specified as minimum duty cycle,
DCMIN. After reaching DCMIN, if CONTROL pin current is
increased further by approximately 0.4 mA, the pulse width
modulator will force the duty cycle from DCMIN to zero in a
discrete step (refer to Figure 4). This feature allows a power
supply to operate in a cycle skipping mode when the load at its
output consumes less power than the power that TOPSwitch-FX
delivers at minimum duty cycle, DCMIN. No additional control
is needed for the transition between normal operation and cycle
skipping. As the load increases or decreases, the power supply
automatically switches between normal operation and cycle
skipping mode as necessary.
Cycle skipping may be avoided, if so desired, by connecting a
minimum load at the power supply output such that the duty
cycle remains at a level higher than DCMIN at all times.
Error Amplifier
The shunt regulator can also perform the function of an error
amplifier in primary feedback applications. The shunt regulator
voltage is accurately derived from a temperature-compensated
bandgap reference. The gain of the error amplifier is set by the
CONTROL pin dynamic impedance. The CONTROL pin
clamps external circuit signals to the VC voltage level. The
CONTROL pin current in excess of the supply current is
separated by the shunt regulator and flows through RE as a
voltage error signal.
On-chip Current Limit with External Programmability
The cycle-by-cycle peak drain current limit circuit uses the
output MOSFET ON-resistance as a sense resistor. A current
6
B
7/01
Time
Figure 6. Switching Frequency Jitter.
limit comparator compares the output MOSFET on-state drain
to source voltage, VDS(ON) with a threshold voltage. High drain
current causes VDS(ON) to exceed the threshold voltage and turns
the output MOSFET off until the start of the next clock cycle.
The default current limit of TOPSwitch-FX is preset internally.
However, with a resistor connected between MULTIFUNCTION pin and SOURCE pin, current limit can be
programmed externally to a lower level between 40% and
100% of the default current limit. Please refer to the graphs in
the typical performance characteristics section for the selection
of the resistor value. By setting current limit low, a
TOPSwitch-FX that is bigger than necessary for the power
required can be used to take advantage of the lower RDS(ON) for
higher efficiency. With a second resistor connected between
the MULTI-FUNCTION pin and the rectified DC high voltage
bus providing a small amount of feed forward current, a true
power limiting operation against line variation can be
implemented. When using an RCD clamp, this feed forward
technique reduces maximum clamp voltage at high line allowing
for higher reflected voltage designs. The current limit
comparator threshold voltage is temperature compensated to
minimize the variation of the current limit due to temperature
related changes in RDS(ON) of the output MOSFET.
The leading edge blanking circuit inhibits the current limit
comparator for a short time after the output MOSFET is turned
on. The leading edge blanking time has been set so that, if a
power supply is designed properly, current spikes caused by
primary-side capacitances and secondary-side rectifier reverse
recovery time will not cause premature termination of the
switching pulse.
The current limit can be lower for a short period after the
leading edge blanking time as shown in Figure 33. This is due
to dynamic characteristics of the MOSFET. To avoid triggering
the current limit in normal operation, the drain current waveform
should stay within the envelope shown.
Line Under-Voltage Detection (UV)
At power up, UV keeps TOPSwitch-FX off until the input line
TOP232-234
voltage reaches the under-voltage threshold. At power down,
UV prevents auto-restart attempts after the output goes out of
regulation. This eliminates power down glitches caused by the
slow discharge of input storage capacitor present in applications
such as standby supplies. A single resistor connected from the
MULTI-FUNCTION pin to the rectified DC high voltage bus
sets UV threshold during power up. Once the power supply is
successfully turned on, UV is disabled to allow extended input
voltage operating range. Input voltage is not checked again
until the power supply loses regulation and attempts another
turn-on. This is accomplished by enabling the UV comparator
only when the divide-by-8 counter used in auto-restart reaches
full count (S7) which is also the state that the counter is reset to
at power up (see Figure 5). The UV feature can be disabled
independent of OV feature as shown in Figure 16.
Line Overvoltage Shutdown (OV)
The same resistor used for UV also sets an overvoltage threshold
which, once exceeded, will force TOPSwitch-FX output into
off-state. The ratio of OV and UV thresholds is preset at 4.5
as can be seen in Figure 8. This feature turns off the
TOPSwitch-FX power MOSFET when the rectified DC high
voltage exceeds the OV threshold. When the MOSFET is off,
the rectified DC high voltage surge capability is increased to the
voltage rating of the MOSFET (700 V), due to the absence of
the reflected voltage and leakage spikes on the drain. Small
amount of hysteresis is provided on the OV threshold to prevent
noise triggering. The OV feature can be disabled independent
of UV feature as shown in Figure 15.
Line Feed Forward with DCMAX Reduction
The same resistor used for UV and OV also implements line
voltage feed forward which minimizes output line ripple and
reduces power supply output sensitivity to line transients. This
feed forward operation is illustrated in Figure 4 by the different
values of IM. Note that for the same CONTROL pin current,
higher line voltage results in smaller operating duty cycle. As
an added safety measure, the maximum duty cycle DCMAX is
also reduced from 78% (typical) at a voltage slightly higher than
the UV threshold to 38% (typical) at the OV threshold (see
Figures 4, 8). DCMAX of 38% at the OV threshold was chosen
to ensure that the power capability of the TOPSwitch-FX is not
restricted by this feature under normal operation.
Remote ON/OFF and Synchronization
TOPSwitch-FX can be turned on or off by controlling the
current into or out from the MULTI-FUNCTION pin (see
Figure 8). This allows easy implementation of remote ON/OFF
control of TOPSwitch-FX in several different ways. A transistor
or an optocoupler output connected between the MULTIFUNCTION pin and the SOURCE pin implements this function
with “active-on” (Figure 19) while a transistor or an optocoupler
output connected between the MULTI-FUNCTION pin and the
CONTROL pin implements the function with “active-off”
(Figure 20).
When a signal is received at the MULTI-FUNCTION pin to
disable the output through any of the MULTI-FUNCTION pin
functions such as OV, UV and remote ON/OFF,
TOPSwitch-FX always completes its current switching cycle as
illustrated in Figure 7 before the output is forced off. The
internal oscillator is stopped slightly before the end of the
current cycle and stays there as long as the disable signal exists.
When the signal at the MULTI-FUNCTION pin changes state
from disable to enable, the internal oscillator starts the next
switching cycle. This approach allows the use of this pin to
synchronize TOPSwitch-FX to any external signal with a
frequency lower than its internal switching frequency.
Oscillator
(SAW)
DMAX
Enable from
M Pin (STOP)
Time
PI-2558-092999
Figure 7. Synchronization Timing Diagram.
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7
TOP232-234
As seen above, the remote ON/OFF feature allows the
TOPSwitch-FX to be turned on and off instantly, on a cycle-bycycle basis, with very little delay. However, remote ON/OFF
can also be used as a standby or power switch to turn off the
TOPSwitch-FX and keep it in a very low power consumption
state for indefinitely long periods. If the TOPSwitch-FX is held
in remote off state for long enough time to allow the CONTROL
pin to dishcharge to the internal supply under-voltage threshold
of 4.8 V (approximately 32 ms for a 47 µF CONTROL pin
capacitance), the CONTROL pin goes into the hysteretic mode
of regulation. In this mode, the CONTROL pin goes through
alternate charge and discharge cycles between 4.8 V and 5.8 V
(see CONTROL pin operation section above) and runs entirely
off the high voltage DC input, but with very low power
consumption (160 mW typical at 230 VAC with M pin open).
When the TOPSwitch-FX is remotely turned on after entering
this mode, it will initiate a normal start-up sequence with softstart the next time the CONTROL pin reaches 5.8 V. In the
worst case, the delay from remote on to start-up can be equal to
the full discharge/charge cycle time of the CONTROL pin,
which is approximately 125 ms for a 47 µF CONTROL pin
capacitor. This reduced consumption remote off mode can
eliminate expensive and unreliable in-line mechanical switches.
It also allows for microprocessor controlled turn-on and turnoff sequences that may be required in certain applications such
as inkjet and laser printers. See Figure 27 under application
examples for more information.
Soft-Start
An on-chip soft-start function is activated at start-up with a
duration of 10 ms (typical). Maximum duty cycle starts from
zero and linearly increases to the default maximum of 78% at
the end of the 10 ms duration. In addition to start-up, soft-start
is also activated at each restart attempt during auto-restart and
when restarting after being in hysteretic regulation of CONTROL
pin voltage (VC), due to remote off or thermal shutdown
conditions. This effectively minimizes current and voltage
stresses on the output MOSFET, the clamp circuit and the
output rectifier, during start-up. This feature also helps minimize
output overshoot and prevents saturation of the transformer
during start-up.
Shutdown/Auto-Restart
To minimize TOPSwitch-FX power dissipation under fault
conditions, the shutdown/auto-restart circuit turns the power
8
B
7/01
supply on and off at an auto-restart duty cycle of typically 4%
if an out of regulation condition persists. Loss of regulation
interrupts the external current into the CONTROL pin. VC
regulation changes from shunt mode to the hysteretic autorestart mode described above. When the fault condition is
removed, the power supply output becomes regulated, VC
regulation returns to shunt mode, and normal operation of the
power supply resumes.
Hysteretic Over-Temperature Protection
Temperature protection is provided by a precision analog
circuit that turns the output MOSFET off when the junction
temperature exceeds the thermal shutdown temperature (135 ˚C
typical). When the junction temperature cools to below the
hysteretic temperature, normal operation resumes. A large
hysteresis of 70 ˚C (typical) is provided to prevent overheating
of the PC board due to a repeating fault condition. VC is
regulated in hysteretic mode and a 4.8 V to 5.8 V (typical)
sawtooth waveform is present on the CONTROL pin when the
power supply is turned off.
Bandgap Reference
All critical TOPSwitch-FX internal voltages are derived from a
temperature-compensated bandgap reference. This reference is
also used to generate a temperature-compensated current
reference which is trimmed to accurately set the switching
frequency, MOSFET gate drive current, current limit, and the
line OV/UV thresholds. TOPSwitch-FX has improved circuitry
to maintain all of the above critical parameters within very tight
absolute and temperature tolerances.
High-Voltage Bias Current Source
This current source biases TOPSwitch-FX from the DRAIN pin
and charges the CONTROL pin external capacitance during
start-up or hysteretic operation. Hysteretic operation occurs
during auto-restart, remote off and over-temperature shutdown.
In this mode of operation, the current source is switched on and
off with an effective duty cycle of approximately 35%. This
duty cycle is determined by the ratio of CONTROL pin charge
(IC) and discharge currents (ICD1 and ICD2). This current source
is turned off during normal operation when the output MOSFET
is switching.
TOP232-234
Using FREQUENCY and MULTIFUNCTION Pins
FREQUENCY (F) Pin Operation
The FREQUENCY pin is a digital input pin available in
TO-220 package only. Shorting the FREQUENCY pin to
SOURCE pin selects the nominal switching frequency of
132 kHz (Figure 10) which is suited for most applications. For
other cases that may benefit from lower switching frequency
such as noise sensitive video applications, a 66 kHz switching
frequency (half frequency) can be selected by shorting the
FREQUENCY pin to the CONTROL pin (Figure 11). In
addition, an example circuit shown in Figure 12 may be used to
lower the switching frequency from 132 kHz in normal operation
to 66 kHz in standby mode for very low standby power
consumption.
for line sensing by connecting a resistor from this pin to the
rectified DC high voltage bus to implement OV, UV and DCMAX
reduction with line voltage functions. In this mode, the value
of the resistor determines the line OV/UV thresholds, and the
DCMAX is reduced linearly with rectified DC high voltage
starting from just above the UV threshold. In high efficiency
applications this pin can be used in the external current limit
mode instead, to reduce the current limit externally to a value
close to the operating peak current, by connecting the pin to the
SOURCE pin through a resistor. The same pin can also be used
as a remote on/off and a synchronization input in both modes.
Please refer to Table 2 for possible combinations of the functions
with example circuits shown in Figure 13 through Figure 23. A
description of specific functions in terms of the MULTIFUNCTION pin I/V characteristic is shown in Figure 8. The
horizontal axis represents MULTI-FUNCTION pin current
with positive polarity indicating currents flowing into the pin.
The meaning of the vertical axes varies with functions. For
those that control the on/off states of the output such as UV, OV
and remote ON/OFF, the vertical axis represents the enable/
disable states of the output. UV triggers at IUV (+50 µA typical)
and OV triggers at IOV (+225 µA typical). Between +50 µA and
+225 µA, the output is enabled. For external current limit and
line feed forward with DCMAX reduction, the vertical axis
represents the magnitude of the ILIMIT and DCMAX. Line feed
forward with DCMAX reduction lowers maximum duty cycle from
78% at IM(DC) (+90 µA typical) to 38% at IOV (+225 µA). External
current limit is available only with negative MULTI-FUNCTION
pin current. Please see graphs in the typical performance
characteristics section for the current limit programming range
and the selection of appropriate resistor value.
MULTI-FUNCTION (M) Pin Operation
When current is fed into the MULTI-FUNCTION pin, it works
as a voltage source of approximately 2.6 V up to a maximum
current of +400 µA (typical). At +400 µA, this pin turns into
a constant current sink. When current is drawn out of the
MULTI-FUNCTION pin, it works as a voltage source of
approximately 1.32 V up to a maximum current of –240 µA
(typical). At –240 µA, it turns into a constant current source.
Refer to Figure 9.
There are a total of five functions available through the use of
the MULTI-FUNCTION pin: OV, UV, line feed forward with
DCMAX reduction, external current limit and remote ON/OFF.
A short circuit between the MULTI-FUNCTION pin and
SOURCE pin disables all five functions and forces
TOPSwitch-FX to operate in a simple three terminal mode like
TOPSwitch-II. The MULTI-FUNCTION pin is typically used
MULTI-FUNCTION PIN TABLE*
▲
Figure Number
14
15
Under-Voltage
✔
✔
Overvoltage
✔
Line Feed Forward (DCMAX)
✔
Three Terminal Operation
13
16
17
18
19
20
21
22
23
✔
✔
✔
✔
✔
✔
Line Feed Forward (ILIMIT)
External Current Limit
✔
✔
Remote ON/OFF
✔
✔
✔
✔
✔
✔
✔
*This table is only a partial list of many MULTI-FUNCTION pin configurations that are possible.
Table 2. Typical MULTI-FUNCTION Pin Configurations.
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9
TOP232-234
IREM(N)
IUV
IOV
(Enabled)
Output
MOSFET
Switching
(Disabled)
Disabled when supply
output goes out of
regulation
IM
ILIMIT (Default)
Current
Limit
IM
DCMAX (78.5%)
Maximum
Duty Cycle
IM
VBG + VTP
MULTIFUNCTION
Pin Voltage
VBG
-250
-200
-150
-100
-50
0
50
100
150
200
250
300
350
400
IM
MULTI-FUNCTION Pin Current (µA)
Note: This figure provides idealized functional characteristics of the MULTI-FUNCTION pin with typical performance values.
Please refer to the parametric table and typical performance characteristics sections of the data sheet for measured data.
PI-2524-081999
Figure 8. MULTI-FUNCTION Pin Characteristics.
CONTROL Pin
TOPSwitch-FX
240 µA
(Negative Current Sense - ON/OFF,
Current Limit Adjustment)
VBG + VT
MULTI-FUNCTION Pin
VBG
(Positive Current Sense - Under-Voltage,
Over-Voltage, Maximum Duty
Cycle Reduction)
400 µA
PI-2548-092399
Figure 9. MULTI-FUNCTION Pin Input Simplified Schematic.
10
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TOP232-234
Typical Uses of FREQUENCY (F) Pin
+
+
DC
Input
Voltage
DC
Input
Voltage
D
CONTROL
C
S
D
CONTROL
C
S
F
F
-
-
PI-2506-081199
PI-2505-081199
Figure 11. Half Frequency Operation (66 kHz).
Figure 10. Full Frequency Operation (132 kHz).
+
DC
Input
Voltage
QS can be an optocoupler output.
D
CONTROL
C
S
-
F
RHF
20 kΩ
STANDBY
QS 47 kΩ
1 nF
PI-2507-040401
Figure 12. Half Frequency Standby Mode (For High Standby
Efficiency).
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11
TOP232-234
Typical Uses of MULTI-FUNCTION (M) Pin
+
+
VUV = IUV x RLS
VOV = IOV x RLS
RLS
DC
Input
Voltage
For RLS = 2 MΩ
VUV = 100 VDC
VOV = 450 VDC
2 MΩ
DC
Input
Voltage
D
M
D
CONTROL
CONTROL
C
C
S
-
DCMAX@100 VDC = 78%
DCMAX@375 VDC = 47%
M
S
PI-2508-081199
Figure 13. Three Terminal Operation (MULTI-FUNCTION
Features Disabled. FREQUENCY Pin Tied to SOURCE
or CONTROL Pin).
+
PI-2509-040401
Figure 14. Line Sensing for Under-Voltage, Overvoltage and
Maximum Duty Cycle Reduction.
+
VUV = RLS x IUV
2 MΩ
RLS
DC
Input
Voltage
For Value Shown
VUV = 100 VDC
D
For Values Shown
VOV = 450 VDC
RLS
DC
Input
Voltage
22 kΩ
30 kΩ
IN4148
M
D
M
CONTROL
CONTROL
C
6.2 V
C
S
-
VOV = IOV x RLS
2 MΩ
S
PI-2510-040401
Figure 15. Line Sensing for Under-Voltage Only (Overvoltage
Disabled).
PI-2516-040401
Figure 16. Line Sensing for Overvoltage Only (Under-Voltage
Disabled).
+
+
For RIL = 12 kΩ
ILIMIT = 67%
RLS
For RIL = 25 kΩ
ILIMIT = 40%
DC
Input
Voltage
See graph for other
resistor values (RIL)
D
DC
Input
Voltage
D
M
RIL
CONTROL
RIL
-
ILIMIT = 90% @ 100 VDC
ILIMIT = 55% @ 300 VDC
2.5 MΩ
C
S
-
M
CONTROL
6 kΩ
C
S
PI-2518-040401
PI-2517-040401
Figure 17. Externally Set Current Limit.
12
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Figure 18. Current Limit Reduction with Line Voltage.
TOP232-234
Typical Uses of MULTI-FUNCTION (M) Pin (cont.)
+
+
QR can be an optocoupler
output or can be replaced by
a manual switch.
QR can be an optocoupler
output or can be replaced
by a manual switch.
QR
DC
Input
Voltage
DC
ON/OFF
Input
47 kΩ
Voltage
M
D
RMC
M 45 kΩ
D
CONTROL
CONTROL
C
QR
C
ON/OFF
47 kΩ
S
-
S
PI-2519-040401
PI-2522-040401
Figure 19. Active-on (Fail Safe) Remote ON/OFF.
Figure 20. Active-off Remote ON/OFF.
+
+
QR can be an optocoupler
output or can be replaced
by a manual switch.
QR can be an optocoupler
output or can be replaced
by a manual switch.
For RIL = 12 kΩ
QR
ILIMIT = 67 %
DC
Input
Voltage
DC
Input
Voltage
For RIL = 25 kΩ
RIL
D
ILIMIT = 40 %
M
ON/OFF
47 kΩ
RMC
CONTROL
RMC = 2RIL
CONTROL
C
QR
24 kΩ
M
D
RIL
C
12 kΩ
ON/OFF
47 kΩ
-
S
S
PI-2520-040401
PI-2521-040401
Figure 21. Active-on Remote ON/OFF with Externally Set Current
Limit.
Figure 22. Active-off Remote ON/OFF with Externally Set Current
Limit.
QR can be an optocoupler
output or can be replaced
by a manual switch.
+
RLS
2 MΩ
QR
DC
ON/OFF
Input
47 kΩ
Voltage
D
For RLS = 2 MΩ
M
CONTROL
C
-
VUV = 100 VDC
VOV = 450 VDC
S
PI-2523-040401
Figure 23. Active-off Remote ON/OFF with Line Sense.
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13
TOP232-234
reflected voltage, by safely limiting the TOPSwitch-FX drain
voltage, with adequate margin, under worst case conditions.
The extended maximum duty cycle feature of TOPSwitch-FX
(guaranteed minimum value of 75% vs. 64% for TOPSwitch-II)
allows the use of a smaller input capacitor (C1). The extended
maximum duty cycle and the higher reflected voltage possible
with the RCD clamp also permit the use of a higher primary to
secondary turns ratio for T1 which reduces the peak reverse
voltage experienced by the secondary rectifier D8. As a result,
a 60 V Schottky rectifier can be used for up to 15 V outputs,
which greatly improves power supply efficiency. The cycle
skipping feature of the TOPSwitch-FX eliminates the need for
any dummy loading for regulation at no load and reduces the no
load/standby consumption of the power supply. Frequency
jitter provides improved margin for conducted EMI meeting the
CISPR 22 (FCC B) specification.
Application Examples
A High Efficiency, 30 W, Universal Input Power Supply
The circuit shown in Figure 24 takes advantage of several of the
TOPSwitch-FX features to reduce system cost and power supply
size and to improve efficiency. This design delivers 30 W at
12 V, from an 85 to 265 VAC input, at an ambient of 50 ˚C, in
an open frame configuration. A nominal efficiency of 80% at
full load is achieved using TOP234.
The current limit is externally set by resistors R1 and R2 to a
value just above the low line operating peak current of
approximately 70% of the default current limit. This allows use
of a smaller transformer core size and/or higher transformer
primary inductance for a given output power, reducing
TOPSwitch-FX power dissipation, while at the same time
avoiding transformer core saturation during startup and output
transient conditions. The resistor R1 provides a feed forward
signal that reduces the current limit with increasing line voltage,
which, in turn, limits the maximum overload power at high
input line voltage. The feed forward function in combination
with the built-in soft-start feature of TOPSwitch-FX, allows the
use of a low cost RCD clamp (R3, C3 and D1) with a higher
A simple Zener sense circuit is used for low cost. The output
voltage is determined by the Zener diode (VR2) voltage and the
voltage drops across the optocoupler (U2) LED and resistor R6.
Resistor R8 provides bias current to Zener VR2 for typical
regulation of ±5% at the 12 V output level, over line and load
and component variations.
CY1
2.2 nF
C14 R15
1 nF 150 Ω
L3
3.3 µH
R3
68 kΩ
2W
C3
4.7 nF
1KV
BR1
600 V
2A
D8
MBR1060
J1
C12
220 µF
35 V
RTN
D2
1N4148
R1
4.7 MΩ
1/2 W
T1
C1
68 µF
400 V
D
U1
TOP234Y
F1
3.15 A
C11
560 µF
35 V
D1
UF4005
L1
20 mH
CX1
100 nF
250 VAC
C10
560 µF
35 V
12 V
@ 2.5 A
R2
9.09 kΩ
M
TOPSwitch-FX
CONTROL
S
F
N
C6
100 nF
R8
150 Ω
U2
LTV817A
C
R5
6.8 Ω
C5
47 µF
10 V
L
R6
150 Ω
VR2
1N5240C
10 V, 2%
PI-2525-040401
Figure 24. 30 W Power Supply using External Current Limit.
14
B
7/01
TOP232-234
35 W Multiple Output Power Supply
Figure 25 shows a five output, 35 W, secondary regulated
power supply utilizing a TOP233 for multiple output applications
such as set-top box, VCR, DVD, etc. The circuit shown is
designed for a 230 VAC input but can be used over the universal
range at a derated output power of 25 W. Alternatively, a
doubler input stage can be used at 100 or 115 VAC for the full
power rating of 35 W. TOPSwitch-FX provides several
advantages in the above mentioned applications.
pin instead of the SOURCE pin in video noise sensitive
applications to allow for heavier snubbing without significant
impact on efficiency.
This design achieves ±5% load regulation on 3.3 V and 5 V
outputs using dual sensed optocoupler feedback through resistors
R9, R10 and R11. Other output voltages are set by the transformer
turns ratio. Output voltage on the low power -5 V output is shunt
regulated by resistor R12 and Zener diode VR2. Dummy load
resistor R13 is required to maintain regulation of the 30 V
output under light load conditions. Compensation of the TL431
(U3) is achieved with resistor R8 and capacitor C7. Primary
side compensation and auto-restart frequency are determined
by resistor R5 and capacitor C5. Second stage LC post-filtering
is used on the 3.3 V, 5 V and 18 V high power outputs (L2, L3,
L4 and C13, C15, C17) for low ripple. Full load operating
efficiency exceeds 75% across the AC input range. Primary
clamp components VR1 and D1 limit peak drain voltage to a
safe value.
A single line sense resistor R1 (2 MΩ) implements an undervoltage detect (at 100 V), over-voltage shutdown (at 450 V) and
line feed forward with DCMAX reduction features. Undervoltage detect ensures that the outputs are glitch free on power
down. The over-voltage shutdown turns off the TOPSwitch-FX
MOSFET above 450 V on the DC input rail, eliminating
reflected voltage and leakage inductance spikes, and hence,
extending the surge withstand to the 700 VDC rating of the
MOSFET. This feature prevents field failures in countries
where prolonged line voltage surges are common.
The frequency jittering in TOPSwitch-FX helps reduce EMI,
maintaining emissions below CISPR 22 (FCC B) levels through
proper choice of Y1 capacitor (CY1) and input filtering elements
(CX1, L1). To minimize coupling of common mode transients
to the TOP233, Y1 capacitor is tied to the positive input DC rail.
Lightning strike immunity to 3 kV is attained with the addition
of a 275 V MOV (RV1).
This design also takes advantage of soft-start and higher operating
frequency to reduce transformer size. A snubber circuit (R4,
C4) is used to slowdown dv/dt of the switching waveform
minimizing radiated video noise that could interfere with TV
reception. The half frequency option of the TOPSwitch-FX can
be used by connecting the FREQUENCY pin to the CONTROL
30 V
@ 100 mA
D8
MUR120
C10
100 µF
50 V
C12
220 µF
25 V
D9
UF5402
CY1
2.2 nF
D10
MBR1045
VR1
P6KE200
BR1
400 V
J1
L
R4
2 kΩ
R13
24 kΩ
5V
@ 2.5 A
3.3 V
@3A
C17
100 µF
10 V
TOP233Y
U1
S
M
U2
LTV817
T1
RV1
275 V
-5 V
@ 100 mA
R10
15.0 kΩ
R7
510 Ω
R9
9.53 kΩ
TOPSwitch-FX
CONTROL
F
C19
100 µF
10 V
R6
51 Ω
C6
100 nF
D
VR2
1N5231
R12
5Ω
D2
1N4148
C4
47 pF
F1
3.15 A
18 V
@ 550 mA
RTN
C18
330 µF
D12
1N5819 10 V
R1
2 MΩ
1/2 W
CX1
0.1 µF
250 VAC
C15
100 µF
10 V
L4
3.3 µH
C16
1000 µF
25 V
D1
UF4007
C13
100 µF
25 V
L3
3.3 µH
C14
1000 µF
25 V
D11
BYW29100
C1
33 µF
400 V
L1
20 mH
C11
1 µF
50 V
L2
3.3 µH
C7
R8
10 Ω 0.1 µF
C
R5
6.8 Ω
C5
47 µF
C8
22 µF
U3
TL431CLP
R11
10.0 kΩ
N
PI-2536-040401
Figure 25. 35 W Set-Top Box Power Supply.
B
7/01
15
TOP232-234
achieved by turning the power supply off when the input
voltage goes below a level needed to maintain output regulation
and keeping it off until the input voltage goes above the
under-voltage threshold (VUV), when the AC is turned on again.
The under voltage threshold is set at 200VDC, slightly below
the required lowest operating DC input voltage, for start-up at
170VAC. This feature saves several components needed to
implement the glitch free turn off with discrete or
TOPSwitch-II based designs.
17 W PC Standby Power Supply
Figure 26 shows a 17 W PC standby application with 3.3 V and
5 V secondary outputs and a 15 V primary output. The supply
uses the TOP232 operating from 230 VAC or 100/115 VAC
with doubler input. This design takes advantage of the softstart, line under-voltage detect, tighter current limit variation
and higher switching frequency features of TOPSwitch-FX. For
example, the higher switching frequency with tighter current
limit variation allows use of an EE19 transformer core.
Furthermore, the spacing between high voltage DRAIN pin and
low voltage pins of the TOPSwitch-FX packages provides large
creepage distance which is a significant advantage in high
pollution environments such as fan cooled PC power supplies.
The bias winding is rectified and filtered by D2 and C6 to create
a bias voltage for the TOP232 and to provide a 15V primary
bias output voltage for the main power supply primary control
circuitry. Both 3.3V and 5V output voltages are sensed by R9,
R10 and R11 using a TL431 (U3) circuit shown. Resistor R6
limits current through optocoupler U2 and sets overall AC
control loop gain. Resistor R7 assures that there is sufficient
bias current for the TL431 when the optocoupler is at a minimum
current. Capacitor C8 provides a soft-finish function to eliminate
turn-on overshoot. The no load regulation (cycle-skipping) of
TOPSwitch-FX permits the circuit to meet the low standby
power requirement of the Blue Angel specification for PCs.
Capacitor C1 provides high frequency decoupling of the high
voltage DC supply, and is necessary only if there is a long trace
length from the source of the DC supply to the inputs of this
standby circuit. The line sense resistor R1 senses the DC input
voltage for line under-voltage. When AC is turned off, the
under-voltage detect feature of the TOPSwitch-FX prevents
auto-restart glitches at the output caused by the slow discharge
of large storage capacitance in the main converter. This is
CY1
1 nF
L1
3.3 µH
D3
SB540
+
VR1
BZY97C-200
C10
1000 µF
10 V
C12
1000 µF
10 V
D4
SB540
200-375
VDC
R1
3.9 MΩ
D1
UF4005
5V
@2A
C11
L2
3.3 µH 100 µF
10 V
3.3 V
@2A
C13
100 µF
10 V
RTN
D2
BAV21
C1
0.01 µF
1 kV
(optional)
T1
D
U1
TOP232Y
M
S
F
R7
510 Ω
C6
35 V
U2
SFH615-2
C
R5
6.8 Ω
C5
47 µF
-
R6
301 Ω
TOPSwitch-FX
CONTROL
15 V
@ 30 mA
C7
0.1 µF
C8
10 µF
35 V
U3
TL431CLP
(Primary
Referenced)
R9
16.2 kΩ
R10
12.1 kΩ
R11
10 kΩ
PI-2537-040401
Figure 26. 17 W PC Standby Supply.
16
B
7/01
TOP232-234
Processor Controlled Supply Turn On/Off
A low cost momentary contact switch can be used to turn the
TOPSwitch-FX power on and off under microprocessor control
that may be required in some applications such as printers. The
low power remote off feature allows an elegant implementation
of this function with very few external components as shown in
Figure 27. Whenever the push button momentary contact switch
P1 is closed by the user, the optocoupler U3 is activated to
inform the microprocessor of this action. Initially, when the
power supply is off (M pin is floating), closing of P1 turns the
power supply on by shorting the M pin of the TOPSwitch-FX to
SOURCE through a diode (remote on). When the secondary
output voltage VCC is established, the microprocessor comes
alive and recognizes that the switch P1 is closed through the
switch status input that is driven by the optocoupler U3 output.
The microprocessor then sends a power supply control signal to
hold the power supply in the on-state through the optocoupler
U4. If the user presses the switch P1 again to command a turn
off, the microprocessor detects this through the optocoupler U3
and initiates a shutdown procedure that is product specific. For
example, in the case of the inkjet printer, the shutdown procedure
may include safely parking the print heads in the storage
position. In the case of products with a disk drive, the shutdown
procedure may include saving data or settings to the disk. After
the shutdown procedure is complete, when it is safe to turn off
the power supply, the microprocessor releases the M pin by
turning the optocoupler U4 off. If the manual switch and the
optocouplers U3 and U4 are not located close to the M pin, a
capacitor CM may be needed to prevent noise coupling to the pin
when it is open.
The power supply could also be turned on remotely through a
local area network or a parallel or serial port by driving the
optocoupler U4 input LED with a logic signal. Sometimes it is
easier to send a train of logic pulses through a cable (due to AC
coupling of cable, for example) instead of a DC logic level as
a wake-up signal. In this case, a simple RC filter can be used to
generate a DC level to drive U4 (not shown in Figure 27). This
remote on feature can be used to wake-up peripherals such as
printers, scanners, external modems, disk drives, etc., as needed
from a computer. Peripherals are usually designed to turn off
automatically if they are not being used for a period of time, to
save power.
VCC
(+5 V)
+
External
Wake-up
Signal
High Voltage
DC Input
100 kΩ
U2
27 kΩ
D
M
TOPSwitch-FX
CONTROL
U3
Power
Supply
ON/OFF
Control
LOGIC LOGIC
INPUT OUTPUT
1N4148
U4
MICRO
PROCESSOR/
CONTROLLER
1N4148
6.8 kΩ
C
6.8 kΩ
CM
S
P1 1 nF
F
U1
-
47 µF
U3
LTV817A
P1 Switch
Status
U4
LTV817A
RETURN
PI-2561-040401
Figure 27. Remote ON/OFF Using Microcontroller.
B
7/01
17
TOP232-234
In addition to using a minimum number of components,
TOPSwitch-FX provides many technical advantages in this
type of application:
1. Extremely low power consumption in the off mode: 80 mW
typical at 110 VAC and 160 mW typical at 230 VAC. This
is because in the remote/off mode the TOPSwitch-FX
consumes very little power, and the external circuitry does
not consume any current (M pin is open) from the high
voltage DC input.
2. A very low cost, low voltage/current, momentary contact
switch can be used.
3. No debouncing circuitry for the momentary switch is required.
During turn-on, the start-up time of the power supply
(typically 10 to 20 ms) plus the microprocessor initiation
time act as a debouncing filter, allowing a turn-on only if the
switch is depressed firmly for at least the above delay time.
During turn-off, the microprocessor initiates the shutdown
18
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7/01
sequence when it detects the first closure of the switch, and
subsequent bouncing of the switch has no effect. If necessary,
the microprocessor could implement the switch debouncing
in software during turn-off, or a filter capacitor can be used
at the switch status input.
4. No external current limiting circuitry is needed for the
operation of the U4 optocoupler output due to internal
limiting of M pin current.
5. No high voltage resistors to the input DC voltage rail are
required to power the external circuitry in the primary. Even
the LED current for U3 can be derived from the CONTROL
pin. This not only saves components and simplifies layout,
but also eliminates the power loss associated with the high
voltage resistors in both on and off states.
6. Robust design: There is no on/off latch that can be accidentally
triggered by transients. Instead, the power supply is held in
the on-state through the secondary side microprocessor.
TOP232-234
Key Application Considerations
TOPSwitch-FX vs. TOPSwitch-ll
Table 3 compares the features and performance differences
between TOPSwitch-FX and TOPSwitch-II. Many of the new
features eliminate the need for costly discrete component.
Other features increase the robustness of design allowing cost
savings in the transformer and other power components.
Function
TOPSwitch-II
TOPSwitch-FX
Soft-Start
N/A*
10 ms
External Current Limit
N/A*
Programmable
100% to 40% of
default current
limit
8, 17,
18, 21,
22
DCMAX
67%
78%
4
Line Feed Forward with
DCMAX Reduction
N/A*
78% to 38%
Line OV Shutdown
N/A*
Line UV Detection
N/A*
Single resistor
programmable
Single resistor
programmable
8, 14,
• Increases voltage withstand cap16, 23
ability against line surge
5, 8, 14, • Prevents auto-restart glitches
15, 23
during power down
Switching Frequency
100 kHz ±10%
132 kHz ±7%
10
Switching Frequency
Option (TO-220 only)
N/A*
66 kHz ±7%
11, 12
Frequency Jitter
N/A*
6, 28
• Reduces conducted EMI
Cycle Skipping
N/A*
±4 kHz@132 kHz
±2 kHz@66 kHz
At DCMIN (1.5%)
4
• Zero load regulation without dummy
load
• Low power consumption at no load
Figures Advantages
• Limits peak current and voltage
component stresses during start-up
• Eliminates external components
used for soft-start in most
applications
• Minimizes output overshoot
• Smaller transformer
• Higher efficiency
• Allows tighter power limit
during output overload conditions
• Smaller input cap (wider dynamic
range)
• Higher power capability (when used
with RCD clamp for large VOR)
• Allows use of Schottky secondary
rectifier diode for up to 15 V output
for high efficiency
4, 8, 14, • Rejects line ripple
23
• Increases transient and surge
voltage withstand capability
• Smaller transformer
• Fundamental below 150 kHz for
conducted EMI
• Lower losses when using RC and
RCD snubber for noise reduction in
video applications
• Allows for higher efficiency in
standby mode
• Lower EMI (second harmonic below
150 kHz)
*Not available
Table 3. Comparison Between TOPSwitch-II and TOPSwitch-FX. (continued on next page)
B
7/01
19
TOP232-234
Function
TOPSwitch-II
TOPSwitch-FX
Figures Advantages
Remote ON/OFF
N/A*
Single transistor
or optocoupler
interface or manual
switch
8, 19,
20, 21,
22, 23,
27
•
•
•
•
•
•
•
Synchronization
Thermal Shutdown
N/A*
Latched
Single transistor
or optocoupler
interface
•
Hysteretic (with
70 °C hysteresis)
• Automatic recovery from thermal
fault
• Large hysteresis prevents circuit
board overheating
• 10% higher power capability due to
tighter tolerance
Current Limit Tolerance ±10% (@25 °C)
±7% (@25 °C)
-8% (0 °C to100 °C) -4% (0 °C to 100 °C)
DRAIN
DIP
Creepage at
SMD
Package
TO-220
DRAIN Creepage at
PCB for TO-220
0.037" / 0.94 mm
0.037" / 0.94 mm
0.046" / 1.17 mm
0.045" / 1.14 mm
Fast on/off (cycle by cycle)
Active-on or active-off control
Low consumption in remote off state
Active-on control for fail-safe
Eliminates expensive in-line on/off
switch
Allows processor controlled turn on/
off
Permits shutdown/wake-up of
peripherals via LAN or parallel port
Synchronization to external lower
frequency signal
Starts new switching cycle on
demand
0.137" / 3.48 mm
0.137" / 3.48 mm
0.068" / 1.73 mm
0.113" / 2.87 mm
(preformed leads)
•
• Greater immunity to arcing as a
result of build-up of dust, debris and
other contaminants
• Preformed leads accommodate
large creepage for PCB layout
• Easier to meet Safety (UL/VDE)
*Not available
Table 3 (cont). Comparison Between TOPSwitch-II and TOPSwitch-FX.
TOPSwitch-FX Design Considerations
TOPSwitch-FX Selection
Selecting the optimum TOPSwitch-FX depends upon required
maximum output power, efficiency, heat sinking constraints
and cost goals. With the option to externally reduce current
limit, a larger TOPSwitch-FX may be used for lower power
applications where higher efficiency is needed or minimal heat
sinking is available.
Input Capacitor
The input capacitor must be chosen to provide the minimum
DC voltage required for the TOPSwitch-FX converter to maintain
regulation at the lowest specified input voltage and maximum
output power. Since TOPSwitch-FX has a higher DCMAX than
TOPSwitch-II, it is possible to use a smaller input capacitor. For
TOPSwitch-FX, a capacitance of 2 µF per watt is usually
sufficient for universal input with an appropriately designed
transformer.
20
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7/01
Primary Clamp and Output Reflected Voltage VOR
A primary clamp is necessary to limit the peak TOPSwitch-FX
drain to source voltage. A Zener clamp (see Figure 26, VR1)
requires few parts and takes up little board space. For good
efficiency, the clamp Zener should be selected to be at least 1.5
times the output reflected voltage VOR as this keeps the leakage
spike conduction time short. When using a Zener clamp in a
universal input application, a VOR of less than 135 V is
recommended to allow for the absolute tolerances and
temperature variations of the Zener. This will ensure efficient
operation of the clamp circuit and will also keep the maximum
drain voltage below the rated breakdown voltage of the
TOPSwitch-FX MOSFET.
A high VOR is required to take full advantage of the wider DCMAX
of TOPSwitch-FX. An RCD clamp provides tighter clamp
voltage tolerance than a Zener clamp and allows a VOR as high
as 165 V. The VOR can be further increased in continuous mode
designs up to 185 V by reducing the external current limit as a
function of input line voltage (see Figure 18). The RCD clamp
TOP232-234
Noise Reduction (dB)
Output Diode
The output diode is selected for peak inverse voltage, output
current, and thermal conditions in the application (including
heat sinking, air circulation, etc.). The higher DCMAX of
TOPSwitch-FX along with an appropriate transformer turns
ratio can allow the use of a 60 V Schoktty diode for higher
efficiency on output voltages as high as 15 V (See Figure 24. A
12 V, 30 W design using a 60 V Schottky for the output diode).
EMI
The frequency jitter feature modulates the switching frequency
over a narrow band as a means to reduce conducted EMI peaks
associated with the harmonics of the fundamental switching
frequency. This is particularly beneficial for average detection
mode. As can be seen in Figure 28, the benefits of jitter increase
with the order of the switching harmonic due to an increase in
frequency deviation.
10
Average
8
6
4
Quasi-Peak
2
0
2nd
3rd
4th
5th
Switching Harmonic
(a)
70
PI-2576-010600
80
TOPSwitch-II (no jitter)
60
Amplitude (dBµV)
Soft-Start
Generally a power supply experiences maximum stress at startup before the feedback loop achieves regulation. For a period
of 10 ms the on-chip soft-start linearly increases the duty cycle
from zero to the default DCMAX at turn on, which causes the
primary current and output voltage to rise in an orderly manner
allowing time for the feedback loop to take control of the duty
cycle. This reduces the stress on the TOPSwitch-FX MOSFET,
clamp circuit and output diode(s), and helps prevent transformer
saturation during start-up. Also, soft-start limits the amount of
output voltage overshoot, and in many applications eliminates
the need for a soft-finish capacitor.
PI-2559-093099
12
is more cost effective than the Zener clamp but requires more
careful design (see quick design checklist).
50
40
30
20
-10
0
VFG243B (QP)
VF646B (AV)
-10
-20
0.15
1
10
30
Frequency (MHz)
(b)
70
PI-2577-010600
80
TOPSwitch-FX (with jitter)
60
Amplitude (dBµV)
The FREQUENCY pin of TOPSwitch-FX offers a switching
frequency option of 132 kHz or 66 kHz. In applications that
require heavy snubbers on the drain node for reducing high
frequency radiated noise (for example, video noise sensitive
applications such as VCR, DVD, monitor, TV, etc.), operating
at 66 kHz will reduce snubber loss resulting in better efficiency.
Also, in applications where transformer size is not a concern,
use of the 66 kHz option will provide lower EMI and higher
efficiency. Note that the second harmonic of 66 kHz is still
below 150 kHz, above which the conducted EMI specifications
get much tighter.
50
40
30
20
-10
0
For 10 W or below, it is possible to use a simple inductor in place
of a more costly AC input common mode choke to meet
worldwide conducted EMI limits.
Transformer Design
It is recommended that the transformer be designed for maximum
operating flux density of 3000 gauss and a peak flux density of
4200 gauss at maximum current limit. The turns ratio should be
chosen for a reflected voltage (VOR) no greater than 135 V when
VFG243B (QP)
VF646B (AV)
-10
-20
0.15
1
10
30
Frequency (MHz)
(c)
Figure 28. (a) Conducted noise improvement for low frequency
harmonics due to jitter, (b) TOPSwitch-II full range EMI
scan (100kHz, no jitter), (c) TOPSwitch-FX full range
EMI scan (132 kHz, with jitter) with identical circuitry
and conditions.
B
7/01
21
TOP232-234
Maximize hatched copper
areas (
) for optimum
heat sinking
Safety Spacing
Y1Capacitor
+
HV
Output Filter Capacitor
J1
Input Filter Capacitor
T
r
a
n
s
f
o
r
m
e
r
PRI
-
S
S
D
BIAS
TOPSwitch-FX
TOP VIEW
M
S
S
SEC
C
Optocoupler
R1
-
DC +
Out
PI-2543-092199
Figure 29. Layout Considerations for TOPSwitch-FX using DIP or SMD (Using Line Sensing for Under-Voltage and Overvoltage).
Maximize hatched copper
areas (
) for optimum
heat sinking
Safety Spacing
Y1Capacitor
+
HV
Output Filter Capacitor
J1
Input Filter Capacitor
PRI
-
D
F
S
R1
BIAS
M
T
r
a
n
s
f
o
r
m
e
r
SEC
C
Heat Sink
TOP VIEW
TOPSwitch-FX
R2
Optocoupler
-
DC +
Out
PI-2544-092199
Figure 30. Layout Considerations for TOPSwitch-FX using TO-220 Package (Using Current Limit Reduction with Line Voltage).
22
B
7/01
TOP232-234
using a Zener clamp, 165 V when using an RCD clamp and
185 V when using RCD clamp with current limit feed forward.
sink attached to the tab should not be electrically tied to any
nodes on the PC board.
For designs where operating current is significantly lower than
the default current limit, it is recommended to use an externally
set current limit close to the operating peak current to reduce
peak flux density and peak power (see Figure 17). In most
applications, the tighter current limit tolerance, higher switching
frequency and soft-start features of TOPSwitch-FX contribute
to a smaller transformer when compared to TOPSwitch-II.
When using P (DIP-8) or G (SMD-8) packages, a copper area
underneath the package connected to the SOURCE pins will act
as an effective heat sink.
In addition, sufficient copper area should be provided at the
anode and cathode leads of the output diode(s) for heat sinking.
Quick Design Checklist
Standby Consumption
Cycle skipping can significantly reduce power loss at zero load,
especially when a Zener clamp is used. For very low secondary
power consumption use a TL431 regulator for feedback control.
Alternately, switching losses can be significantly reduced by
switching from 132 kHz in normal operation to 66 kHz under
light load conditions.
TOPSwitch-FX Layout Considerations
Primary Side Connections
Use a single point (Kelvin) connection at the negative terminal
of the input filter capacitor for TOPSwitch-FX SOURCE pin
and bias winding return. This improves surge capabilities by
returning surge currents from the bias winding directly to the
input filter capacitor.
The CONTROL pin bypass capacitor should be located as close
as possible to the SOURCE and CONTROL pins and its
SOURCE connection trace should not be shared by the main
MOSFET switching currents.
All SOURCE pin referenced components connected to the
MULTI-FUNCTION pin should also be located close to
SOURCE and MULTI-FUNCTION pins with dedicated SOURCE
pin connection. The MULTI-FUNCTION pin's trace should be
kept as short as possible and away from the DRAIN trace to
prevent noise coupling. Line sense resistor (R1 in Figures 29 and
30) should be located close to the MULTI-FUNCTION pin to
minimize the trace length on the MULTI-FUNCTION pin side.
In addition to the 47 µF CONTROL pin capacitor, a high frequency
bypass capacitor in parallel may be used for better noise immunity.
The feedback optocoupler output should also be located close to
the CONTROL and SOURCE pins of TOPSwitch-FX.
Y-Capacitor
The Y-capacitor should be connected close to the secondary
output return pin(s) and the primary DC input pin of the
transformer (see Figures 29 and 30).
Heat Sinking
The tab of the Y package (TO-220) is internally electrically
tied to the SOURCE pin. To avoid circulating currents, a heat
As with any power supply design, all TOPSwitch-FX designs
should be verified on the bench to make sure that components
specifications are not exceeded under worst case conditions.
The following minimum set of tests is strongly recommended:
1. Maximum drain voltage – Verify that peak VDS does not
exceed 675 V at highest input voltage and maximum overload
output power. Maximum overload output power occurs
when the ouput is overloaded to a level just before the power
supply goes into auto-restart (loss of regulation).
2. Maximum drain current – At maximum ambient temperature,
maximum input voltage and maximum output load, verify
drain current waveforms at start-up for any signs of
transformer saturation and excessive leading edge current
spikes. TOPSwitch-FX has a leading edge blanking time of
200 ns to prevent premature termination of the on-cycle.
Verify that the leading edge current spike is below the
allowed current limit envelope (see Figure 33) for the drain
current waveform at the end of the 200 ns blanking period.
3. Thermal check – At maximum output power, minimum
input voltage and maximum ambient temperature, verify
that temperature specifications are not exceeded for
TOPSwitch-FX, transformer, output diodes and output
capacitors. Enough thermal margin should be allowed for
the part-to-part variation of the RDS(ON) of TOPSwitch-FX as
specified in the data sheet. The margin required can either
be calculated from the tolerances or it can be accounted for
by connecting an external resistance in series with the
DRAIN pin and attached to the same heatsink, having a
resistance value that is equal to the difference between the
measured RDS(ON) of the device under test and the worst case
maximum specification.
Design Tools
1. Technical literature: Data Sheet, Application Notes,
Design Ideas, etc.
2. Transformer design spreadsheet.
3. Engineering prototype boards.
Up to date information on design tools can be found at Power
Integrations Web site: www.powerint.com
B
7/01
23
TOP232-234
ABSOLUTE MAXIMUM RATINGS(1)
DRAIN Voltage ............................................ -0.3 to 700 V
DRAIN Peak Current: TOP232 ................................. 0.8 A
TOP233 ................................. 1.6 A
TOP234 ................................. 2.4 A
CONTROL Voltage .......................................... -0.3 to 9 V
CONTROL Current ...............................................100 mA
MULTI-FUNCTION Pin Voltage .................... -0.3 to 9 V
FREQUENCY Pin Voltage ............................... -0.3 to 9 V
Storage Temperature ..................................... -65 to 150 °C
Operating Junction Temperature(2) ................ -40 to 150 °C
Lead Temperature(3) ................................................ 260 °C
Notes:
1. All voltages referenced to SOURCE, TA = 25 °C.
2. Normally limited by internal circuitry.
3. 1/16" from case for 5 seconds.
THERMAL IMPEDANCE
Thermal Impedance: Y Package (θJA)(1) ............... 70 °C/W
(θJC)(2) ................. 2 °C/W
P/G Package:
(θJA) ........ 45 °C/W(3); 35 °C/W(4)
(θJC)(5) .......................... 11 °C/W
Notes:
1. Free standing with no heatsink.
2. Measured at the back surface of tab.
3. Soldered to 0.36 sq. inch (232 mm2), 2oz. (610 gm/m2) copper clad.
4. Soldered to 1 sq. inch (645 mm2), 2oz. (610 gm/m2) copper clad.
5. Measured on the SOURCE pin close to plastic interface.
Conditions
Parameter
Symbol
(Unless Otherwise Specified)
See Figure 34
SOURCE = 0 V; TJ = -40 to 125 °C
Min
Typ
Max
FREQUENCY Pin
Connected to SOURCE
124
132
140
FREQUENCY Pin
Connected to CONTROL
61.5
Units
CONTROL FUNCTIONS
Switching
Frequency
(average)
fOSC
Frequency Jitter
Deviation
∆f
Frequency Jitter
Modulation Rate
fM
Maximum Duty
Cycle
DCMAX
Minimum Duty
Cycle (Prior to
Cycle Skipping)
DCMIN
Soft Start Time
tSOFT
PWM
Gain
24
B
7/01
IC = 4 mA;
TJ = 25 °C
kHz
66
132 kHz Operation
±4
66 kHz Operation
±2
70.5
kHz
250
IC = ICD1
Hz
IM ≤ IM(DC)
75.0
78.0
82.0
IM = 190 µA
35.0
47.0
57.0
0.8
1.5
2.7
%
10
14
ms
-22
-17
%/mA
TJ = 25 °C; DCMIN to DCMAX
IC = 4 mA; TJ = 25 °C
-27
%
TOP232-234
Conditions
Parameter
Symbol
(Unless Otherwise Specified)
See Figure 34
SOURCE = 0 V; TJ = -40 to 125 °C
Min
Typ
Max
Units
CONTROL FUNCTIONS (cont.)
PWM Gain
Temperature Drift
External Bias
Current
lB
See Figure 4
CONTROL
Current at Start of
Cycle Skipping
Dynamic
Impedance
- 0.01
See Note A
1.2
TJ = 25 °C
ZC
IC = 4 mA; TJ = 25 °C
See Figure 32
10
%/mA/°C
1.9
2.8
mA
5.9
7.5
mA
15
22
Ω
Dynamic
Impedance
Temperature Drift
0.18
%/°C
Control Pin
Internal Filter Pole
7
kHz
SHUTDOWN/AUTO-RESTART
Control Pin
Charging Current
lC (CH)
Charging Current
Temperature Drift
Auto-restart Upper
Threshold Voltage
TJ = 25 °C
VC = 0 V
-5.0
-3.8
-2.6
VC = 5 V
-3.0
-1.9
-0.8
See Note A
vC(AR)
0.5
%/°C
5.8
V
Auto-restart Lower
Threshold Voltage
4.5
4.8
Auto-restart
Hysteresis Voltage
0.8
1.0
2
4
Auto-restart Duty
Cycle
Auto-restart
Frequency
mA
1.0
5.1
V
V
8
%
Hz
B
7/01
25
TOP232-234
Conditions
Parameter
Symbol
(Unless Otherwise Specified)
See Figure 34
SOURCE = 0 V; TJ = -40 to 125 °C
Min
Typ
Max
Units
44
50
54
µA
210
225
240
µA
MULTI-FUNCTION INPUT
Line Under-Voltage
Threshold Current
lUV
Line Over-Voltage
or Remote ON/
OFF Threshold
Current and
Hysteresis
IOV
Remote ON/OFF
Negative Threshold
Current and
Hysteresis
IREM (N)
MULTI-FUNCTION
Pin Short Circuit
Current
MULTI-FUNCTION
Pin Voltage
Maximum Duty
Cycle Reduction
Onset Threshold
Current
TJ = 25 °C
Threshold
TJ = 25 °C
Threshold
-43
VM = VC
VM = 0 V
VM
IM (DC)
Maximum Duty
Cycle Reduction
Slope
-27
300
400
520
Normal Mode
-300
-240
-180
Auto-restart Mode
lM = 50 µA
lM = 225 µA
-110
-90
-70
2.00
2.50
2.60
2.90
3.00
3.30
lM = -50 µA
1.25
1.32
1.39
lM = -150 µA
1.18
1.24
1.30
75
90
110
TJ = 25 °C
0.30
MULTI-FUNCTION
Pin Floating
VDRAIN = 150 V
0.6
µA
µA
-7
IM > IM (DC)
Remote OFF
DRAIN Supply
Current
-35
TJ = 25 °C
Hysteresis
IM (SC)
µA
10
Hysteresis
µA
V
µA
%/µA
1.1
mA
MULTI-FUNCTION
Pin Shorted to
CONTROL
1.0
1.8
Remote ON Delay
TRON
From Remote On to Drain Turn-On
See Note B
1.5
2.5
4.0
µs
Remote OFF
Setup Time
TROFF
Minimum Time Before Drain
Turn-On to Disable Cycle
See Note B
1.5
2.5
4.0
µs
26
B
7/01
TOP232-234
Conditions
Parameter
Symbol
(Unless Otherwise Specified)
See Figure 34
SOURCE = 0 V; TJ = -40 to 125 °C
Min
Typ
Max
Units
FREQUENCY INPUT
FREQUENCY Pin
Threshold Voltage
VF
See Note B
1.0
2.9
VC -1.0
V
FREQUENCY Pin
Input Current
IF
VF = VC
10
22
40
µA
0.465
0.500
0.535
0.930
1.000
1.070
1.500
1.605
CIRCUIT PROTECTION
Self Protection
Current Limit
ILIMIT
TOP232 Internal; di/dt = 100mA/µs
TJ= 25 °C
See Note C
TOP233 Internal; di/dt = 200mA/µs
TJ= 25 °C
See Note C
TOP234
TJ= 25 °C
Internal; di/dt = 300mA/µs
See Figure 33
TJ = 25 °C
1.395
See Note C
≤ 85 VAC
0.75 x
(Rectified Line Input) ILIMIT(MIN)
A
Initial Current Limit
IINIT
Leading Edge
Blanking Time
tLEB
IC = 4 mA
200
ns
Current Limit Delay
tILD
IC = 4 mA
100
ns
Thermal Shutdown
Temperature
125
Thermal Shutdown
Hysteresis
Power-up Reset
Threshold Voltage
A
265 VAC
0.6 x
(Rectified Line Input) ILIMIT(MIN)
135
150
°C
70
VC(RESET)
Figure 34, S1 open
2.0
°C
3.3
4.3
V
OUTPUT
ON-State
Resistance
RDS(ON)
TJ = 25 °C
TOP232
ID = 50 mA
TJ = 100 °C
15.6
25.7
18.0
30.0
TOP233
ID = 100 mA
TJ = 25 °C
TJ = 100 °C
7.8
12.9
9.0
15.0
TOP234
ID = 150 mA
TJ = 25 °C
TJ = 100 °C
5.2
8.6
6.0
10.0
Ω
B
7/01
27
TOP232-234
Conditions
Parameter
Symbol
(Unless Otherwise Specified)
See Figure 34
SOURCE = 0 V; TJ = -40 to 125 °C
Min
Typ
Max
Units
150
µA
OUTPUT (cont.)
Off-State
Current
Breakdown
Voltage
IDSS
VM = Floating; IC = 4mA
VDS = 560 V; TJ = 125 °C
BVDSS
VM = Floating; IC = 4mA
ID = 100 µA; TJ = 25 °C
Rise
Time
tR
Fall
Time
tF
700
Measured in a Typical
V
100
ns
50
ns
Flyback Converter Application
SUPPLY VOLTAGE CHARACTERISTICS
DRAIN Supply
Voltage
Shunt Regulator
Voltage
VC(SHUNT)
See Note D
36
IC = 4 mA
5.60
Shunt Regulator
Temperature Drift
V
5.85
6.10
±50
lCD1
Output
MOSFET Enabled
VM = 0 V
1.0
lCD2
Output
MOSFET Disabled
VM = 0 V
0.3
Control Supply/
Discharge Current
1.5
V
ppm/°C
2.0
mA
0.6
1.0
NOTES:
A. For specifications with negative values, a negative temperature coefficient corresponds to an increase in
magnitude with increasing temperature, and a positive temperature coefficient corresponds to a decrease in
magnitude with increasing temperature.
B. Guaranteed by characterization. Not tested in production.
C. For externally adjusted current limit values, please refer to the graph (Current Limit vs. External Current Limit
Resistance) in the Typical Performance Characteristics section.
D. It is possible to start up and operate TOPSwitch-FX at DRAIN voltages well below 36 V. However, the CONTROL
pin charging current is reduced, which affects start-up time, auto-restart frequency, and auto-restart duty cycle.
Refer to the characteristic graph on CONTROL pin charge current (IC) vs. DRAIN voltage for low voltage operation
characteristics.
28
B
7/01
TOP232-234
t2
t1
HV
90%
90%
DRAIN
VOLTAGE
t
D= 1
t2
10%
0V
PI-2039-033001
100
DRAIN Current (normalized)
PI-1939-091996
CONTROL Pin Current (mA)
120
80
60
40
Dynamic
1
=
Impedance Slope
20
tLEB (Blanking Time)
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
PI-2022-033001
Figure 31. Duty Cycle Measurement.
IINIT(MIN) @ 85 VAC
IINIT(MIN) @ 265 VAC
ILIMIT(MAX) @ 25 °C
ILIMIT(MIN) @ 25 °C
0
0
2
4
6
8
10
0
1
2
3
CONTROL Pin Voltage (V)
5
6
7
8
Time (us)
Figure 33. Drain Current Operating Envelope.
Figure 32. CONTROL Pin I-V Characteristic.
S1
4
470 Ω
5W
100 kΩ
S3
5-50 V
40 V
0-60 kΩ
M
470 Ω
D
CONTROL
C
C
TOPSwitch-FX
S2
S4
0-15 V
47 µF
F
S
0.1 µF
NOTES: 1. This test circuit is not applicable for current limit or output characteristic measurements.
2. For P and G packages, short all SOURCE pins together.
PI-2538-040401
Figure 34. TOPSwitch-FX General Test Circuit.
B
7/01
29
TOP232-234
BENCH TEST PRECAUTIONS FOR EVALUATION OF ELECTRICAL CHARACTERISTICS
restart mode, there is only a 12.5% chance that the CONTROL
pin oscillation will be in the correct state (drain active state) so
that the continuous drain voltage waveform may be observed.
It is recommended that the VC power supply be turned on first
and the DRAIN pin power supply second if continuous drain
voltage waveforms are to be observed. The 12.5% chance of
being in the correct state is due to the divide-by-8 counter.
Temporarily shorting the CONTROL pin to the SOURCE pin
will reset TOPSwitch-FX, which then will come up in the
correct state.
The following precautions should be followed when testing
TOPSwitch-FX by itself outside of a power supply. The schematic
shown in Figure 34 is suggested for laboratory testing of
TOPSwitch-FX.
When the DRAIN pin supply is turned on, the part will be in the
auto-restart mode. The CONTROL pin voltage will be oscillating
at a low frequency between 4.8 and 5.8 V and the drain is turned
on every eighth cycle of the CONTROL pin oscillation. If the
CONTROL pin power supply is turned on while in this auto-
Typical Performance Characteristics
CURRENT LIMIT vs. MULTI-FUNCTION
PIN CURRENT
1.0
200
.9
180
.8
160
.7
140
.6
120
100
Scaling Factors:
TOP234 1.50
TOP233 1.00
TOP232 0.50
.5
.4
.3
-250
di/dt (mA/µs)
Current Limit (A)
PI-2540-033001
80
60
-200
-150
-100
-50
0
IM (µA)
CURRENT LIMIT vs. EXTERNAL
CURRENT LIMIT RESISTANCE
PI-2539-033001
1.0
Scaling Factors:
TOP234 1.50
TOP233 1.00
TOP232 0.50
Current Limit (A)
.9
.8
.7
140
.6
120
Typical
.5
100
Maximum and minimum levels
are based on characterization.
.4
80
.3
0
5K
10K
15K
20K
External Current Limit Resistor RIL (Ω)
30
B
7/01
180
160
Maximum
Minimum
200
25K
60
30K
di/dt (mA/µs)
1.1
TOP232-234
Typical Performance Characteristics (cont.)
BREAKDOWN vs. TEMPERATURE
1.0
1.0
0.8
0.6
0.4
0.2
0
0.9
0
25
50
75 100 125 150
-50 -25
Junction Temperature (°C)
50
75 100 125 150
EXTERNAL CURRENT LIMIT vs.
TEMPERATURE with RIL = 12 kΩ
PI-2555-033001
1.2
1.0
Current Limit (A)
0.8
0.6
0.4
0.2
0.8
0.6
Scaling Factors:
TOP234 1.50
TOP233 1.00
TOP232 0.50
0.4
0.2
0
0
-50 -25
0
25
50
-50 -25
75 100 125 150
50
75 100 125 150
0.8
0.6
0.4
0.2
1.2
Under-Voltage Threshold
(Normalized to 25 °C)
PI-2553-033001
1.0
25
UNDER-VOLTAGE THRESHOLD
vs. TEMPERATURE
OVER-VOLTAGE THRESHOLD
vs. TEMPERATURE
1.2
0
Junction Temperature (°C)
Junction Temperature (°C)
PI-2552-033001
Current Limit
(Normalized to 25 °C)
1.0
25
Junction Temperature (°C)
INTERNAL CURRENT LIMIT
vs. TEMPERATURE
1.2
0
PI-2554-033001
-50 -25
Over-Voltage Threshold
(Normalized to 25 °C)
PI-1123A-033001
1.2
Output Frequency
(Normalized to 25 °C)
PI-176B-033001
Breakdown Voltage
(Normalized to 25 °C)
1.1
FREQUENCY vs. TEMPERATURE
1.0
0.8
0.6
0.4
0.2
0
0
-50 -25
0
25
50
75 100 125 150
Junction Temperature (°C)
-50 -25
0
25
50
75 100 125 150
Junction Temperature (°C)
B
7/01
31
TOP232-234
Typical Performance Characteristics (cont.)
MULTI-FUNCTION PIN VOLTAGE
vs. CURRENT
4
3
2
See
Expanded
Version
1
0
-300 -200 -100 0
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
100 200 300 400 500
-300 -250
MULTI-FUNCTION Pin Current (µA)
0.8
0.6
0.4
0.2
1.0
0.8
0.6
0.4
0.2
25
50
75 100 125 150
-50 -25
Scaling Factors:
TOP234 1.00
TOP233 0.67
TOP232 0.33
2
CONTROL Pin
Charging Current (mA)
1
0.5
50
75 100 125 150
IC vs. DRAIN VOLTAGE
PI-1940-033001
TCASE = 25 °C
TCASE = 100 °C
25
Junction Temperature (°C)
OUTPUT CHARACTERISTICS
1.5
0
PI-2564-101499
0
Junction Temperature (°C)
DRAIN Current (A)
0
0
-50 -25
VC = 5 V
1.6
1.2
0.8
0.4
0
0
0
2
4
6
DRAIN Voltage (V)
B
7/01
-50
1.2
0
32
-150 -100
MAX. DUTY CYCLE REDUCTION ONSET
THRESHOLD CURRENT vs. TEMPERATURE
Onset Threshold Current
(Normalized to 25 °C)
PI-2562-033001
CONTROL Current
(Normalized to 25 °C)
1.0
-200
MULTI-FUNCTION Pin Current (µA)
CONTROL CURRENT at START of
CYCLE SKIPPING vs. TEMPERATURE
1.2
PI-2541-091699
1.6
PI-2563-033001
5
MULTI-FUNCTION Pin Voltage (V)
PI-2542-091699
MULTI-FUNCTION Pin (V)
6
MULTI-FUNCTION PIN VOLTAGE
vs. CURRENT (EXPANDED)
8
10
0
20
40
60
DRAIN Voltage (V)
80
100
TOP232-234
Typical Performance Characteristics (cont.)
COSS vs. DRAIN VOLTAGE
100
10
PI-1942-033001
Scaling Factors:
TOP234 1.00
TOP233 0.67
TOP232 0.33
Scaling Factors:
TOP234 1.00
TOP233 0.67
TOP232 0.33
300
Power (mW)
DRAIN Capacitance (pF)
1000
PI-1941-033001
DRAIN CAPACITANCE POWER (132 kHz)
200
100
0
0
200
400
DRAIN Voltage (V)
600
0
200
400
600
DRAIN Voltage (V)
B
7/01
33
TOP232-234
TO-220-7B
.165 (4.19)
.185 (4.70)
.400 (10.16)
.415 (10.54)
.146 (3.71)
.156 (3.96)
+
.108 (2.74) REF
.045 (1.14)
.055 (1.40)
.236 (5.99)
.260 (6.60)
.570 (14.48)
REF.
.467 (11.86)
.487 (12.37)
7° TYP.
.860 (21.84)
.880 (22.35)
.670 (17.02)
REF.
.095 (2.41)
.115 (2.92)
PIN 4
PIN 1 & 7
.028 (.71)
.032 (.81)
.050 (1.27) BSC
PIN 1
.040 (1.02)
.060 (1.52)
.040 (1.02)
.060 (1.52)
.010 (.25) M
.015 (.38)
.020 (.51)
.150 (3.81) BSC
.190 (4.83)
.210 (5.33)
.050 (1.27)
.050 (1.27)
.050 (1.27)
.050 (1.27)
.180 (4.58)
.200 (5.08)
PIN 7
PIN 1
.150 (3.81)
Y07B
.150 (3.81)
MOUNTING HOLE PATTERN
Notes:
1. Controlling dimensions are inches. Millimeter
dimensions are shown in parentheses.
2. Pin locations start with Pin 1, and continue
from left to right when viewed from the front.
Pins 2 and 6 are omitted.
3. Dimensions do not include mold flash or
other protrusions. Mold flash or protrusions
shall not exceed .006 (.15mm) on any side.
4. Minimum metal to metal spacing at the package body for omitted pin locations is .068
inch (1.73 mm).
5. Position of the formed leads to be measured
at the mounting plane, .670 inch (17.02 mm)
below the hole center.
6. All terminals are solder plated.
PI-2560-033001
34
B
7/01
TOP232-234
DIP-8B
⊕ D S .004 (.10)
Notes:
1. Package dimensions conform to JEDEC specification
MS-001-AB (Issue B 7/85) for standard dual-in-line (DIP)
package with .300 inch row spacing.
2. Controlling dimensions are inches. Millimeter sizes are
shown in parentheses.
3. Dimensions shown do not include mold flash or other
protrusions. Mold flash or protrusions shall not exceed
.006 (.15) on any side.
4. Pin locations start with Pin 1, and continue counter-clockwise to Pin 8 when viewed from the top. The notch and/or
dimple are aids in locating Pin 1. Pin 6 is omitted.
5. Minimum metal to metal spacing at the package body for
the omitted lead location is .137 inch (3.48 mm).
6. Lead width measured at package body.
7. Lead spacing measured with the leads constrained to be
perpendicular to plane T.
-E-
.245 (6.22)
.255 (6.48)
Pin 1
-D-
.375 (9.53)
.385 (9.78)
.128 (3.25)
.132 (3.35)
.057 (1.45)
.063 (1.60)
(NOTE 6)
0.15 (.38)
MINIMUM
-TSEATING
PLANE
.100 (2.54) BSC
.010 (.25)
.015 (.38)
.125 (3.18)
.135 (3.43)
.300 (7.62) BSC
(NOTE 7)
.300 (7.62)
.390 (9.91)
.048 (1.22)
.053 (1.35)
.014 (.36)
.022 (.56) ⊕ T E D S .010 (.25) M
P08B
PI-2551-033001
SMD-8B
⊕ D S .004 (.10)
-E-
.372 (9.45)
.388 (9.86)
⊕ E S .010 (.25)
.245 (6.22)
.255 (6.48)
Pin 1
.100 (2.54) (BSC)
-D-
.375 (9.53)
.385 (9.78)
.057 (1.45)
.063 (1.60)
(NOTE 5)
.128 (3.25)
.132 (3.35)
.032 (.81)
.037 (.94)
.048 (1.22)
.053 (1.35)
Notes:
1. Controlling dimensions are
inches. Millimeter sizes are
shown in parentheses.
2. Dimensions shown do not
include mold flash or other
protrusions. Mold flash or
protrusions shall not exceed
.006 (.15) on any side.
.420
3. Pin locations start with Pin 1,
and continue counter-clock
.046 .060 .060 .046
Pin 8 when viewed from the
top. Pin 6 is omitted.
4. Minimum metal to metal
.080
spacing at the package body
Pin 1
for the omitted lead location
is .137 inch (3.48 mm).
.086
5. Lead width measured at
.186
package body.
.286
6. D and E are referenced
Solder Pad Dimensions
datums on the package
body.
Heat Sink is 2 oz. Copper
As Big As Possible
.004 (.10)
.009 (.23)
.004 (.10)
.012 (.30)
.036 (0.91)
.044 (1.12)
0°- 8°
G08B
PI-2546-040501
B
7/01
35
TOP232-234
Revision Notes
A
Date
1/00
1) Corrected rounding of operating frequency (132/66 kHz).
2) Corrected spelling.
B
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3) Corrected Storage Temperature θJC and updated nomenclature in parameter table.
For the latest updates, visit our Web site: www.powerint.com
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Power Integrations does not assume any liability arising from the use of any device or circuit described herein, nor does it
convey any license under its patent rights or the rights of others.
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©Copyright 2001, Power Integrations, Inc.
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AMERICAS
Power Integrations, Inc.
5245 Hellyer Avenue
San Jose, CA 95138 USA
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+1 408-414-9200
Customer Service:
Phone:
+1 408-414-9665
Fax:
+1 408-414-9765
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Easthampstead Road
Bracknell
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International Holdings, Inc.
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International Holdings, Inc.
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+86-755-367-5143
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