ADDTEK AMC3844B

AMC3842B/43B/44B/45B
CURRENT MODE PWM CONTROLLER
www.addmtek.com
DESCRIPTION
FEATURES
The AMC3842B/43B/44B/45B are fixed frequency
current-mode PWM controllers specially designed for
OFF-Line switching power supply and DC-to-DC converters
with a minimum number of external components. These
devices feature a trimmed oscillator for precise duty cycle
control, a temperature compensated reference, high gain error
amplifier, current sensing comparator, and high current totem
pole output which is suitable for driving MOSFETs.
„
The under voltage lock-out (U.V.L.O.) is designed to
operated with 200µA start-up current in typical, allowing an
efficient bootstrap supply voltage design. The U.V.L.O.
thresholds for the AMC3842B/44B are 16V (on) and 10V
(off), which are ideal for off-line applications. The
corresponding typical threshold for the AMC3843/45BB is
8.4V (on) and 7.6V (off). The AMC3842B/43B can operate
within 100% duty cycle and the AMC3844B/45B can operate
within 50% duty cycle.
„
APPLICATIONS
„
„
„
„
„
„
„
„
Low Start-Up current (max. 200µA)
Optimized for Off-Line and DC-to-DC
Converters
Maximum Duty Cycle
U.V.L.O. with Hysteresis
Operating Frequency Up to 500KHz
Internal Trimmed Bandgap Reference
High Current Totem Pole Output
Error Amplifier With Low Output Resistance
Available in 8-Pin Plastic DIP and Surface
Mount 14-Pin S.O.I.C.
Identical pin assignment to earlier UC384X
series.
PACKAGE PIN OUT
VREF
COMP
„
„
„
Off-line flyback or forward converters.
DC-to-DC buck or boost converter.
Monitor Power Supply
VFB
VCC
ISENSE
OUTPUT
RT/CT
GND
8-Pin Plastic DIP
(Top View)
Start-UP
Voltage
Device
Hysteresis
Max. Duty
Cycle
AMC3842B
16V
6V
< 100%
AMC3843B
8.4V
0.8V
< 100%
AMC3844B
16V
6V
< 50%
AMC3845B
8.4V
0.8V
< 50%
TA (OC)
0 to 70
0 to 70
Note:
VREF
COMP
AVAILABLE OPTIONS
NC
VFB
NC
VCC
NC
VC
ISENSE
VREF
RT/CT
GND
OUTPUT
NC
GND
RT/CT
PWR
14-Pin Plastic S.O.I.C.
Surface Mount
(Top View)
ORDER INFORMATION
Plastic DIP-8
Plastic SO-14
M 8-pin
D 14-pin
AMC384XBM
AMC384XBD
AMC384XBM (Lead Free)
AMC384XBD (Lead Free)
1. All surface-mount packages are available in Tape & Reel.
AMC384XBDMT).
2. The letter ”F” is marked for Lead Free process.
Copyright © 2006 ADDtek Corp.
COMP
VFB
ISENSE
1
VCC
OUTPUT
8-Pin Plastic S.O.I.C.
Surface Mount
(Top View)
Plastic SO-8
DM 8-pin
AMC384XBDM
AMC384XBDM (Lead Free)
Append the letter “T” to part number (i.e. AMC384XBDT, or
DD019_F -- OCTOBER 2006
AMC3842B/43B/44B/45B
ABSOLUTE MAXIMUM RATINGS
(Note 1)
35V
± 1A
-0.3V to 6.3V
10mA
1W
150 OC
-65OC to 150OC
260 OC
Supply voltage, VCC
Output current, IO
Analog inputs, VI
Error amp output sink current, ISINK(EA)
Power dissipation (TA = 25 OC), PD
Maximum juncture temperature, TJ
Storage temperature range
Lead temperature (soldiering, 10 seconds)
Note 1:
Exceeding these ratings could cause damage to the device.
negative out of the specified terminal.
All voltages are with respect to Ground.
Currents are positive into,
THERMAL DATA
M PACKAGE:
Thermal Resistance-Junction to Ambient, θJA
95 OC/W
D PACKAGE:
Thermal Resistance-Junction to Ambient, θJA
120 OC/W
DM PACKAGE:
Thermal Resistance-Junction to Ambient, θJA
165 OC/W
Junction Temperature Calculation: TJ = TA + (PD × θJA).
The θJA numbers are guidelines for the thermal performance of the device/pc-board system.
All of the above assume no ambient airflow.
Copyright © 2006 ADDtek Corp.
2
DD019_F --
OCTOBER 2006
AMC3842B/43B/44B/45B
BLOCK DIAGRAM
7 (12)
Internal
Bias
VREF
U.V.L.O.
36V
5V
EN
VREF
8 (14)
5 (9) GND
VREF
Good Logic
Error Amp
VFB
2R
1V
R
COMP 1 (1)
RT/CT
7 (11) PWR
VC
Current
Sense
2 (3)
CURRENT
SENSE
VCC
PWM
Latch
R
OUTPUT
6 (10)
S
3 (5)
4 (7)
T
PWR
5 (8) GND
Oscillator
( ) are 14 Pin S.O.I.C. pin number
Note 2:
VCC and PWR VC are internally connected for 8 pin packages.
Note 3:
PWR GND and GND are internally connected for 8 pin packages.
Note 4:
U.V.L.O. is 16V for 3842B/44B and 8.4V for 3843B/45B.
Note 5:
Hysteresis is 6V for 3842B/44B and 0.8V for 3843B/45B.
Note 6:
Toggle flip flop used only in 3844B/45B
Copyright © 2006 ADDtek Corp.
3
DD019_F --
OCTOBER 2006
AMC3842B/43B/44B/45B
Supply Voltage
RECOMMENDED OPERATING CONDITIONS
Recommended Operating Conditions
Parameter
Symbol
Min.
Typ.
Max.
VCC / VC
30
VI,RT/CT
Input Voltage
VI,ISENSE/VFB
VO, Output
ICC
IO
IO(REF)
CT
fOSC
TA
Output Voltage
Supply Current
Average Output Current
Reference Output Current
Timing Capacitor
Oscillator Frequency
Operating Free-air Temperature
Units
V
0
5.5
V
0
30
25
200
-20
V
mA
mA
mA
nF
KHz
O
C
1
100
500
70
0
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, these specifications apply over the operating ambient temperature for AMC384XB with
0OC ≤ TA ≤70 OC; VCC = 15V(note 7); RT = 10K;CT = 3.3nF. Low duty cycle pulse testing techniques are used which
maintains junction and case temperatures equal to the ambient temperature.
Parameter
Symbol
AMC384XB
Test Conditions
Units
Min.
Typ.
Max.
4.9
5.0
5.1
V
-30
6
6
-100
20
25
-180
mV
mV
mA
52
0.2
57
1.0
KHz
%
Reference Section
Reference output Voltage
VREF TJ = 25 OC, IREF = 1mA
Line Regulation
Load Regulation
Short Ciruit Output Current
ISC
Oscillator Section
Oscillation Frequency
f
Frequency Change with Voltage
Frequency Change with Temperature
(note 8)
Peak-to-peak Amplitude At RT/CT
VOSC
Current Sense Section
Gain (note 9 & 10)
AVOL
Maximum Input Signal (note 9)
VI(MAX)
Power Supply Rejection Ratio (note 9) PSRR
Input Bias Current
IBIAS
Copyright © 2006 ADDtek Corp.
12V ≤ VCC ≤ 25V,TJ = 25 C
1mA ≤ IREF ≤ 20mA
TJ = 25 OC
O
TJ = 25 OC
12V ≤ VCC ≤ 25V
47
TMIN ≤ TA ≤ TMAX
COMP = 5V
12V ≤ VCC ≤ 25V (note 9)
4
2.85
0.9
5
%
1.7
V
3.00
1.0
70
-3.0
DD019_F --
3.15
1.1
-10
V/V
V
dB
µA
OCTOBER 2006
AMC3842B/43B/44B/45B
ELECTRICAL CHARACTERISTICS (Continued)
Error Amplifier Section
Input Bias Current
Input Voltage
Open Loop Voltage Gain
Unity Gain Bandwidth (note 8)
Power Supply Rejection Ratio
Output Sink Current
Output Source Current
High Output Voltage
Low Output Voltage
Output Section
IBIAS
VI(EA)
GVO
UGBW
PSRR
ISINK
ISOURCE
VOH
VOL
Output Low Level
VOL
Output High Level
VOH
Rise Time (note 9)
Fall Time (note 9)
Under-Voltage Lockout Section
Start Threshold
tr
tf
VTH(ST)
Min. Operating Voltage
COMP = 2.5V
2V ≤ VO ≤ 4V
TJ = 25 OC
12V ≤ VCC ≤ 25V
VFB = 2.7V, COMP = 1.1V
VFB = 2.3V, COMP = 5.0V
VFB = 2.3V, RL = 15KΩ to GND
VFB = 2.7V, RL = 15KΩ to VREF
ISINK = 20mA
ISINK = 200mA
ISOURCE = 20mA
ISOURCE = 200mA
TJ = 25 OC, CL = 1nF
TJ = 25 OC, CL = 1nF
2.42
65
0.7
60
2
-0.5
5
13
12
-0.1
2.50
90
1
70
7
-1.0
6
0.7
-2
2.58
0.1
1.4
13.5
13.0
50
50
0.4
2.2
150
150
1.1
µA
V
dB
MHz
dB
mA
mA
V
V
V
V
AMC3842B/44B
AMC3843B/45B
AMC3842B/44B
AMC3843B/45B
14.5
7.8
8.5
7.0
16.0
8.4
10
7.6
17.5
9.0
11.5
8.2
AMC3842B/43B
AMC3844B/45B
94
47
97
48
100
50
ns
ns
V
V
PWM Section
Maximum Duty Cycle
Dmax
%
Total Standby Current
Startup Current
Operating Supply Current
Zener Voltage
Note 7:
Note 8:
Note 9:
Note 10:
ICC
VZ
AMC3842B/44B
AMC3843B/45B
VFB = ISENSE = 0V
ICC = 25mA
30
14
35
0.2
0.2
17
mA
mA
V
Adjust VCC above the start threshold before setting at 15V
These parameters, although guaranteed, are not 100% tested in production prior to shipment
Parameters are measured at trip point of latch with VFB = 2V
Gain is measured between ISENSE and COMP with the input changing from 0V to 0.8V
Copyright © 2006 ADDtek Corp.
5
DD019_F --
OCTOBER 2006
AMC3842B/43B/44B/45B
CHARACTERIZATION CURVES
Below characterization curves was referenced by Fig.4
O s cillator D is charge Current vs .
Tem perature
Maximum Output Duty Cycle vs. Timing
Resistor
100
9
Vcc=15V
Vosc=2V
8.5
Idischg
(mA)
Idischg=7.5mA
90
80
Idischg=8.8mA
Dmax 70
(%)
60
8
7.5
Vcc=15V
Ct=3.3mF
TA=25ºC
50
40
7
-50
-25
0
25
50
75
100
0
125
1
2
3
Ø
1.2
30
1
60
0.8
100
Gain
60
Phase
Vcc=15V
120
Vth 0.6
(V)
0.4
Vo=2V to 4V
150
0.2
180
0
(dB) 40
90
0
RL=100K
-20
10
100
1K
10K
100K
TA=-40ºC
1
2
3
Vcc=15V
4
5
6
7
8
Vo(V)
60
Reference Short Circuit Current vs.
Temperature.
110
Vcc=15V
50
Vcc=15V
RL≤0.1Ω
100
40
90
30
Isc80
(mA)
70
TA=125ºC
8
TA=125ºC
0
1M
R e fe re nc e Vol t a ge C ha nge vs. S ourc e
C urre nt .
10
7
TA=25ºC
f(Hz)
20
6
C urre nt S e nse Input Thre shol d vs.
Error Amp Out put Vol t a ge .
Error Amp Open-Loop Gain and Phase vs.
Frequency
20
5
RT (KΩ )
TA(ºC)
80
4
TA=25ºC
TA=-40ºC
60
0
0
20
40
60
80
100
50
120
-50
Iref(mA)
Copyright © 2006 ADDtek Corp.
-25
0
25
50
75
100
125
150
TA(ºC)
6
DD019_F --
OCTOBER 2006
AMC3842B/43B/44B/45B
APPLICATION INFORMATION
Error
Amp
2R
R
1V
Current
Sense
Comparator
COMP
Rf
ISENSE
Cf
RS
GND
Fig. 1. Current Sense Circuit
Peak current (IS) is set by: IS(MAX) = 1V/RS
2.5V
Error
Amp
VREF
0.5mA
RT
VFB
Zi
Zf
RT/CT
CT
COMP
GND
Fig. 3. Oscillator Section
Fig. 2. Error Amplifier Configuration - the
For RT < 5K, f =
amplifier can source or sink up to 0.5mA
1.72
RTCT
VREF
RT
4.7K
VCC
2N2222
100K
1K
Error AMP
Adjust
5K
4.7K
ISENSE
Adjust
COMP
VREF
VFB
VCC
0.1µF
1K,
1W
Output
ISENSE Output
RT/CT
GND
0.1µF
GND
Fig. 4. Open-loop laboratory test fixture: CarefulCgrounding
techniques are necessary for high peak currents
T
associated with capacitive loads. Timing and bypass capacitors should be connected to GND pin in a single
point ground. The transistor and 5K potentiometer are used to sample the oscillator waveform and apply an
adjustable ramp to the ISENSE pin
Copyright © 2006 ADDtek Corp.
7
DD019_F --
OCTOBER 2006
AMC3842B/43B/44B/45B
APPLICATION INFORMATION (continued)
1K
COMP
VREF
Shutdown
330Ω
ISENSE
Shutdown
500Ω
To Current
Sense Resistor
Fig. 5. Shutdown Techniques - there are two ways to shutdown the PWM controller: 1) raise the voltage at
ISENSE above 1V or, 2) pull the COMP below a voltage two diodes above ground.
VREF
0.1µF
RT
RT/CT
CT
ISENSE
R2
R1
ISENSE
RSENSE
C
Fig 6. Slop Compensation – To achieve duty cycles over 50% for some applications, the above
slope compensation technique is suggested by resistively summing a fraction of the oscillator
ramp with the current sense signal.
Copyright © 2006 ADDtek Corp.
8
DD019_F --
OCTOBER 2006
AMC3842B/43B/44B/45B
PACKAGE
8-Pin Plastic DIP
INCHES
MILLIMETERS
5
8
MIN
TYP
MAX
MIN
TYP
MAX
A
0.355 0.365 0.400
9.02
9.27
10.16
B
0.240 0.250 0.280
6.10
6.35
7.11
-
5.08
5.33
D 0.014 0.018 0.022 0.356
0.46
0.55
F
1.15
1.52
1.65
B
1
4
C
A
L
F
G
C
-
0.200 0.210
0.045 0.060 0.065
-
0.100
-
-
2.54
-
-
0.090
1.27
-
2.29
J
0.008 0.010 0.015
0.20
0.25
0.38
K
0.115 0.130 0.150
2.92
3.30
3.81
L
0.300 BSC.
H 0.050
J
K
H
G
M
D
M
0º
7º
7.62 BSC.
15º
0º
7º
15º
8-Pin Plastic S.O.I.C.
INCHES
A
B
MILLIMETERS
MIN
TYP
MAX
MIN
TYP
MAX
A
0.183
-
0.202
4.65
-
5.13
B
0.144 0.156 0.163
3.66
3.95
4.14
C
0.068
0.074
1.35
-
1.88
D
0.010 0.016 0.020
0.25
0.41
0.51
F
0.015 0.020 0.035
0.38
0.50
0.89
G
0.050 BSC
P
-
F
D
G
L
C
SEATING PLAN
K
J
0.007
-
0.010
0.19
-
0.25
K
0.005
-
0.010
0.13
-
0.25
L
0.189
-
0.205
4.80
-
5.21
M
0º
-
8º
0º
-
8º
5.79
6.00
6.20
M
J
P
Copyright © 2006 ADDtek Corp.
1.27 BSC
9
0.228 0.236 0.244
DD019_F --
OCTOBER 2006
AMC3842B/43B/44B/45B
14-Pin Plastic S.O.I.C.
INCHES
A
B
P
F
G
TYP
MAX
MIN
TYP
MAX
A
0.336
-
0.344
8.54
-
8.74
B
0.159
-
0.158
3.81
-
4.01
C 0.053
-
0.069
1.35
-
1.75
D 0.014
-
0.018
0.35
-
0.46
F
-
0.030
0.67
-
0.77
0.026
G
C
Copyright © 2006 ADDtek Corp.
MIN
D
L
SEATING PLAN
MILLIMETERS
K
M
J
10
0.050 BSC
1.27 BSC
J
0.007
-
0.010
0.19
-
0.25
K
0.004
-
0.010
0.10
-
0.25
L
0.189
-
0.205
4.82
-
5.21
M
-
-
8º
-
-
8º
P
0.228
-
0.244
5.79
-
6.20
DD019_F --
OCTOBER 2006
AMC3842B/43B/44B/45B
IMPORTANT NOTICE
ADDtek reserves the right to make changes to its products or to discontinue any integrated circuit product or service
without notice, and advises its customers to obtain the latest version of relevant information to verify, before placing
orders, that the information being relied on is current.
A few applications using integrated circuit products may involve potential risks of death, personal injury, or severe
property or environmental damage. ADDtek integrated circuit products are not designed, intended, authorized, or
warranted to be suitable for use in life-support applications, devices or systems or other critical applications. Use of
ADDtek products in such applications is understood to be fully at the risk of the customer. In order to minimize risks
associated with the customer’s applications, the customer should provide adequate design and operating safeguards.
ADDtek assumes to no liability to customer product design or application support. ADDtek warrants the performance of
its products to the specifications applicable at the time of sale.
ADDtek Corp.
9F, No. 20, Sec. 3, Bade Rd., Taipei, Taiwan, 105
TEL: 2-25700299
FAX: 2-25700196
Copyright © 2006 ADDtek Corp.
11
DD019_F --
OCTOBER 2006