Rohm BD8622EFV Built-in 1ch fet light load type dc/dc converter Datasheet

TECHNICAL NOTE
System Power Supply for TV Series
Built-in 1ch FET
Light Load Type
DC/DC converters
BD8622EFV
●Description
BD8622EFV has realized the high performance and reliability required as a power supply for thin-screen TV.
Due to the high-speed load response, it is most suitable for TV-purpose processors with increasingly high performance, and due to the
wide phase margin it leaves a good margin for board pattern & constant setting and so facilitates its application design.
As a high-reliability design, it has various built-in protection circuits (overcurrent protection, output voltage abnormal protection, thermal
protection, and off-latch function at the time of abnormality etc.), therefore as an advantage it does not easily damage in every possible
abnormal condition such as all-pin short circuit test etc. and hence most suitable for thin-screen TV which requires the high reliability.
●Features
1) High efficiency in all load area
2) 3.0A output current
3) PWM mode/PFM mode switch(automatic operation)
4) Low current mode/Rorripplmord switch with terminal MODE
5) Low RDS(ON) internal switches:75mΩ(typ.)
6) ±1% reference voltage accuracy
7) Programmable frequency : 250kHz-1MHz
(Can the adjustment by an external synchronization and the terminal RT resistance.)
8) Terminal RT OPEN/SHORT detecting function
9) Over current protection function
10) Output over voltage/low voltage protection function (over : FB > VREF +60mV , low : FB < VREF -60mV)
11) Timer off latch function in abnormal circumstances
12) Thermal shutdown function
13) Under voltage protection
14) Soft start/start delay circuit
15) Soft start time out function
16) Protecting BUS function with terminal PDET
17) HTSSOP-B20 package
Jul. 2008
● Electrical characteristic
(Unless otherwise noted Ta=25℃, VIN=3.3V, GND=0V)
Parameter
VIN supply current (operating)
VIN supply current (standby)
Reference voltage (VREF)
Output rise detection voltage
Output decrease detection voltage
Terminal PDET output current
Oscillation frequency
Pch FET ON resistance
UVLO voltage
SW leak current
EN terminal H threshold voltage
EN terminal L threshold voltage
FC sink current
FC source current
SS/DELAY terminal source current
Terminal PDET pull-up resistor
Symbol
IQ_active
IQ_stby
VREF
VOVP
VLVP
IPDET
fOSC
RPFET
VUVLO
ILSW
VENH
VENL
IFCSI
IFCSO
ISSSO
RPDET
Specification value
MIN
TYP
MAX
0.792
30
-90
0.4
500
2.35
1.1
10
2
100
210
0
0.8
60
-60
550
75
2.50
0
20
-20
4
170
350
1
0.808
90
-30
600
110
2.65
1
0.4
-10
6
250
UNIT
μA
μA
V
mV
mV
mA
kHz
mΩ
V
μA
V
V
μA
μA
μA
kΩ
Condition
VFB = 0.83V, VFC = 1V
VEN = 0V
Monitoring FB terminal
Monitoring FB terminal
VPDET< 0.3V
RRT= 220kΩ
ISW = 1A
VEN= 0V, VIN = 5.5V
VFB :FB terminal voltage, VEN :EN terminal voltage, VFC :FC terminal voltage, VPDET: PDET terminal voltage
Current capability should not exceed Pd.
2 / 15
● Block Diagram
OSC
Err AMP
Detect Abnormal
Voltage
and Start error
Shut
Down
en
enable
PWM/PFM
CONTROL
SVIN
Predrive
10
VIN
Fig1 Block diagram
● Pin Description
No.
Symbol
1
Description
Explanation
SGND
Signal GND terminal
Small signal system GND
2
FB
Feed back terminal
Output voltage detection
3
PDET
Abnormal state notification and external IC
Protecting BUS communication terminal
abnormality detection terminal
4
NC
5
SW
6
SW
7
SW
8
SW
9
NC
10
PGND
11
VIN
12
VIN
13
VIN
14
VIN
15
NC
16
EN
17
MODE
18
19
20
Switching output terminal
Power GND terminal
GND for power MOSFET
Power supply input terminal
Power supply input. The decoupling is done to PGND
Enable input
ON/OFF control for device operation
The operation mode is switched according to the input voltage
MODE selection terminal
at a light load.
The soft start time is adjusted with the connected capacitor
SS/DELAY Soft start adjustment capacity connection terminal
FC
Error amplifier output
Error amplifier phase compensation point
RT
Frequency adjustment resistance connection terminal
The switching frequency is set by the connected resistance
3 / 15
● Pin equivalence circuit diagram
No.
Symbol
Explanation
Terminal equivalent circuit diagram
1
SGND
GND (connected 0V)
2
FB
Output voltage detection terminal
3
PDET
Protecting BUS I/O terminal
5,6,7,8
SW
Output terminal
10
PGND
Power GND
(Same voltage as SGND)
11,12,13
PVIN
Power supply input terminal
14
SVIN
Power supply input terminal
4 / 15
No.
Symbol
Explanation
16
EN
Enable terminal
17
MODE
Operation mode switch terminal
at light load
Terminal equivalent circuit diagram
5 / 15
No.
Symbol
Explanation
18
SS
/DELAY
Soft start time adjustment
terminal
19
FC
Error amplifier compensation
terminal
20
RT
Oscillator frequency adjustment
terminal
Terminal equivalent circuit diagram
6 / 15
● Operation description
Enable control
The device can be controlled ON/OFF by EN terminal (16 pin) voltage.
An internal circuit starts when VEN reaches 1.1V.
When standing up of VIN is too steep (1msec or less), a defective start might be caused according to the state of Pascon between
GND substrate pattern and power supply-when the terminal EN is short-circuited to the terminal VIN and it is used.
Fig.2
ON/OFF transition wave form in EN controlling
7 / 15
Soft start time set function
As for BD8622EFV, output can do soft start without overshoot by charging soft start capacity (CSS) connected between
SS and SGND terminal.
Also, soft start time (tss) can be set by setting soft start capacity (CSS) arbitrarily.
OSC oscillation frequency setting function
The output oscillation frequency can be set by connecting resistance between terminal RT (20 pins) and SGND
(range = 250kHz - 1MHz)
The relation between RT terminal resistance and the oscillation frequency follows Fig.4.
Frequency [kHz]
スイッチング周波数 [kHz]
1000
10
10
100
1000
RT端子抵抗
[kΩ]
RT terminal
resistance [kΩ]
Fig.4 RT resistance-oscillation frequency
8 / 15
10000
Light load mode operation
・Low current mode
When the terminal MODE (17 pins) is made "H", low current mode operation becomes effective. The characteristic of the
efficiency valuing is obtained in low current mode operation at a light load.
VOUT
[20mV/DIV]
SW
[2V/DIV]
IL
[200mA/DIV]
Fig.5 Low current mode operation
・Low ripple mode
When the terminal MODE is made "L", the Low ripple mode operation becomes effective. It becomes operation of valuing
a low ripple in the Low ripple mode operation at a light load.
VOUT
[20mV/DIV]
SW
[2V/DIV]
IL
[200mA/DIV]
Fig.6 Low ripplemord operation
100
90
80
Low current
mode
ローカレントモード
60
効率[%]
Efficiency [%]
70
50
ローリップルモード
Low
ripple mord
40
VIN=3.3V
VO=1.8V
Io=0~100mA
SW_f=550KHz(R11=220KΩ)
30
20
10
0
1
10
負荷電流[mA]
Negative overcurrent [mA]
Fig7 Light load mode efficiency comparison
9 / 15
100
● Protection function
Protection circuit is effective for destruction prevention due to accident so that avoid using under continuous protection
operation.
Low voltage protection function (LVP)
The voltage of the terminal FB (2 pins) is compared with internal reference voltage VREF.
If FB terminal voltage falls below VLVP(= VREF -60mV) and the state continues for 500us, output changes to low voltage
and the state is fixed. In that case , PDET (3pin) output changes to L.
Table 4-1 output low voltage protection function
EN
terminal
>VENH
<VENL
SS terminal
>1.4V(typ)
<1.4V(typ)
-
FB terminal
Low voltage
protection function
<VLVP
>VLVP
-
Effective
Invalidity
Invalidity
Low voltage
protection operation
ON
OFF
OFF
OFF
* Low voltage protection function is available when SS terminal voltage becomes more than
1.4V (typ) in the transition to ON control (during soft start).
Over voltage protection function(OVP)
The voltage of the terminal FB is compared with internal reference voltage VREF.
If FB terminal voltage is over Vovp (=VREF +60mV) and the state is continues for 500usec, output changes to low voltage
and the state is fixed.
Table 4-2 output overvoltage protection function
EN
terminal
>VENH
<VENL
SS terminal
>1.4V(typ)
<1.4V(typ)
-
FB terminal
Over voltage
protection function
>VOVP
<VOVP
-
Effective
Invalidity
Invalidity
Over voltage
protection operation
ON
OFF
OFF
OFF
* Over voltage protection function is available when SS terminal voltage becomes more than
1.4V (typ) in the transition to ON control (during soft start).
Fig.8 Output voltage error detection range
10 / 15
Under voltage lock out protection (UVLO)
As for BD8622EFV, the power-supply voltage decrease detection protection circuit is built in.
It the input voltage decrease below the UVLO voltage (2.5V typ), the device state changes to the standby mode (Moreover,
to prevent the chattering of the output) hysteresis width of 100mV(typ) has been installed in the UVLO cancel voltage.
RT terminal open/short protection function (RTO/RTS)
RT terminal opening/short protection function prevent the clock from abnormal oscillation.
If RT terminal open/short protection function is detected, output voltage changes to low level and is fixed.
Terminal RT opening/short protection function is available if the state continue for 500usec, abnormal
detection operates when the state continues about 500μsec(typ).
Soft start time-out function
If VSS doesn't exceed VSSTH within 64msec (typ) since a soft start began, BD8622EFV controls an off latch.
Vo is fixed in a low level.
Fig.9 Soft start time-out
Thermal shut down function
Thermal shut down circuit (TSD circuit) is built into BD8622EFV. When the temperature of the chip exceeds Tjmax=175,
the DC/DC converter is fixed in a low voltage.
TSD function is aimed to shut down IC from thermal reckless driving under an abnormal state to exceed Tjmax=175.
It aims at neither protection nor the guarantee of the set. Therefore, please do not use this function to protect the set.
Over current protection function
The over current protection function has been achieved by limiting the current that flows on high side MOSFET.
The current is controlled in every one cycle of the switching frequency. When an abnormal state continues for about
500μsec(typ), the output is fixed in a low level.
11 / 15
Protecting BUS function with terminal PDET
The terminal PDET (3 pins) monitors whether IC is normal or not. When IC becomes abnormal, the PDET output is
reduced at "L" level with the output voltage fixed “L” level at the same time. Moreover, it is possible to make the output fix in
a low level by compulsorily reducing the terminal PDET at "L" level from the outside.
When two or more BD8622EFV is used in the application, this function prevents the IC from destroying, because one IC
error transmits all other ICs by PDET line in the condition that PDET terminals are connected each other.
Fig.6 Protecting BUS communication
※Please give the terminal PDET as OPEN when you do not use protecting BUS function.
Error detection (off latch) release method
BD8622EFV enters the state of an off latch when the protection function operates.
To release the off latch state, EN terminal voltage should be changed to low level once time.
12 / 15
● Each characteristic reference data
Vout : 100mV/div
VIN = 5V
Io = 3A
Vout : 20mV/div
Io = 1A/div
100usec/div
1usec/div
Fig.11 Output load response
Fig.12 Output ripple
100
90
VIN = 3.3V
80
VIN = 2V/div
70
EFFICIENCY [%]
60
VIN = 5.0V
50
VOUT = 0.5V/div
40
VOUT = 1.8V
30
fosc = 550kHz
20
LC mode
SS = 2V/div
10
0
1
10
100
1000
10000
10msec/div
LOAD CURRENT [mA]
Fig.13 Efficiency
Fig.14 Soft start
2.0
VIN = 5.0V
OUTPUT VOLTAGE : Vo [V]
1.9
VOUT = 1.8V
1.8
1.7
1.6
1.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
LOAD CURRENT [A]
Fig.15 Regulation
13 / 15
ERROR AMP REFERENCE VOLTAGE : VREF [V]
0.810
5.0
0.808
VIN = 3.3V
VIN = 3.3V
4.8
SS CHARGE CURRENT : Iss [μA]
0.806
0.804
0.802
0.800
0.798
0.796
0.794
4.5
4.3
4.0
3.8
3.5
3.3
0.792
3.0
0.790
-25
0
25
50
75
100
125
-25
150
0
25
AMBIENT TEMPERATURE : Ta [℃]
Reference voltage - Temperature characteristic
Fig.16
75
100
125
150
Fig.17 SS Charging current - Temperature characteristic
600.0
600.0
590.0
590.0
Ta = 25℃
VIN = 3.3V
580.0
FREQUENCY : Fosc [kHz]
580.0
570.0
FREQUENCY : Fosc [kHz]
50
AMBIENT TEMPERATURE : Ta [℃]
560.0
550.0
540.0
530.0
570.0
560.0
550.0
540.0
530.0
520.0
520.0
510.0
510.0
500.0
500.0
2.5
3
3.5
4
4.5
5
-25
5.5
0
25
Fig.18
50
75
100
125
150
AMBIENT TEMPERATURE : Ta [℃ ]
INPUT VOLTAGE : Vin [V]
Fig.19
Switching frequency-power-supply voltage characteristic
100.0
Switching frequency-temperature characteristic
110.00
90.0
Ta = 25℃
VIN = 3.3V
100.00
ON‐RESISTANCE: Ron [mΩ]
ON‐RESISTANCE: Ron [mΩ]
80.0
70.0
60.0
50.0
40.0
30.0
20.0
90.00
80.00
70.00
60.00
50.00
40.00
10.0
30.00
0.0
2.5
3
3.5
4
4.5
5
-25
5.5
0
25
Fig.20 PMOS on resistance-power-supply voltage
75
100
125
150
Fig.21 PMOS on resistance-temperature characteristic
400.0
1.00
VIN = 3.3V
0.90
350.0
0.80
Ta = 25℃
300.0
CIRCUIT CURRENT: Icc [uA]
EN VOLTAGE HIGH: VENH [V]
50
AMBIENT TEMPERATURE : Ta [℃ ]
INPUT VOLTAGE : Vin [V]
0.70
0.60
0.50
0.40
0.30
0.20
250.0
200.0
150.0
VFB = 0.83V
100.0
VFC = 1.0V
SW = H
50.0
0.10
0.0
0.00
-25
0
25
50
75
100
125
150
2.5
3
3.5
4
4.5
5
5.5
INPUT VOLTAGE : Vin [V]
AMBIENT TEMPERATURE : Ta [℃ ]
Fig.22 Terminal EN H voltage-temperature characteristic
Fig.23 Circuit current-power-supply voltage characteristic
14 / 15
HTSSOP-B20
<Dimension>
<Tape and Reel information>
6.5 ± 0.1
11
6.4 ± 0.2
4.4 ± 0.1
0.5 ± 0.15
1.0 ± 0.2
20
1
10
Embossed carrier tape
Quantity
2500pcs
Direction
E2
(The direction is the 1pin of product is at the upper left when you hold
reel on the left hand and you pull out the tape on the right hand)
of feed
0.17 +0.05
−0.03
S
0.08 S
1234
1234
1234
1pin
1234
(Unit:mm)
1234
Reel
1234
0.2 +0.05
−0.04
1234
0.65
1234
1.0Max.
0.85 ± 0.05
0.08 ± 0.05
0.325
Tape
Direction of feed
※When you order , please order in times the amount of package quantity.
Catalog No.08T274A '08.7 ROHM ©
Appendix
Notes
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The contents described herein are subject to change without notice. The specifications for the
product described in this document are for reference only. Upon actual use, therefore, please request
that specifications to be separately delivered.
Application circuit diagrams and circuit constants contained herein are shown as examples of standard
use and operation. Please pay careful attention to the peripheral conditions when designing circuits
and deciding upon circuit constants in the set.
Any data, including, but not limited to application circuit diagrams information, described herein
are intended only as illustrations of such devices and not as the specifications for such devices. ROHM
CO.,LTD. disclaims any warranty that any use of such devices shall be free from infringement of any
third party's intellectual property rights or other proprietary rights, and further, assumes no liability of
whatsoever nature in the event of any such infringement, or arising from or connected with or related
to the use of such devices.
Upon the sale of any such devices, other than for buyer's right to use such devices itself, resell or
otherwise dispose of the same, no express or implied right or license to practice or commercially
exploit any intellectual property rights or other proprietary rights owned or controlled by
ROHM CO., LTD. is granted to any such buyer.
Products listed in this document are no antiradiation design.
The products listed in this document are designed to be used with ordinary electronic equipment or devices
(such as audio visual equipment, office-automation equipment, communications devices, electrical
appliances and electronic toys).
Should you intend to use these products with equipment or devices which require an extremely high level
of reliability and the malfunction of which would directly endanger human life (such as medical
instruments, transportation equipment, aerospace machinery, nuclear-reactor controllers, fuel controllers
and other safety devices), please be sure to consult with our sales representative in advance.
It is our top priority to supply products with the utmost quality and reliability. However, there is always a chance
of failure due to unexpected factors. Therefore, please take into account the derating characteristics and allow
for sufficient safety features, such as extra margin, anti-flammability, and fail-safe measures when designing in
order to prevent possible accidents that may result in bodily harm or fire caused by component failure. ROHM
cannot be held responsible for any damages arising from the use of the products under conditions out of the
range of the specifications or due to non-compliance with the NOTES specified in this catalog.
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Appendix1-Rev2.0
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