Gamma GM3842A Current mode pwm controller Datasheet

GM3842A, GM3843A
GM3844A, GM3845A
CURRENT MODE PWM CONTROLLER
Description
Features
GM384XA series is high performance with fixedfrequency current mode PWM controllers. They
are specially designed for off-Line and DC-to-DC
converter applications with minimum 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.
‹
Low Start-Up and Operating Current
‹
Automatic Feed Forward Compensation
‹
Current Mode Operating Frequency up to
500KHz
‹
Trimmed Oscillator Discharge Current for
Precise Duty Cycle Control
‹
Latching PWM for Cycle-By-Cycle
Current Limiting
The under voltage lock-out (U.V.L.O.) is
designed to operated with 0.17mA typ. start-up
current, allowing an efficient bootstrap supply
voltage design. The U.V.L.O. thresholds for the
AMC3842A/44A are 16V (on) and 10V (off)
which are ideal for off-line applications. The
corresponding typical threshold for the
GM3843A/45A is 8.4V (on) and 7.6V (off). The
GM3842A/43A can operated within 100% duty
cycle and the GM3844A/45A can operated within
50% duty cycle.
‹
Under Voltage Lockout with Hysteresis
‹
High Current totem Pole Output Stage
Available Options
Application
Hysteresis
Max. Duty
Cycle
Off-line flyback or forward converters
GM3842A
16V
6V
< 100%
Monitor Power Supply
GM3843A
8.4V
0.8V
< 100%
GM3844A
16V
6V
< 50%
GM3845A
8.4V
0.8V
< 50%
DC-to DC buck boost converter
GM384x V1.00
Start-UP
Voltage
Device
www.gammamicro.com.tw 1
GM3842A, GM3843A
GM3844A, GM3845A
CURRENT MODE PWM CONTROLLER
Marking Information and Pin Configurations (Top View)
SO8
7.
DIP8
6. Output
VCC
-
GM384X
AYWW
1. COMP
2.
FB
6. Output
5. GND
7. VCC
8. VREF
5. GND
8. VREF
GM384X
AYWW
4.
RT / CT
3.
ISENSE
4. RT / CT
3. ISENSE
1. Output A
2. Input A -
A: Assembly / Test site code
Y: Year
WW: Week
Ordering Information
GM384x V1.00
Ordering Number
2
Package
Shipping
GM3842AD8T
DIP-8
60 Units / Tube
GM3842AS8T
SOP-8
100 Units / Tube
GM3842AS8R
SOP-8
2,500 Units / Tape & Reel
GM3843AD8T
DIP-8
60 Units / Tube
GM3843AS8T
SOP-8
100 Units / Tube
GM3843AS8R
SOP-8
2,500 Units / Tape & Reel
GM3844AD8T
DIP-8
60 Units / Tube
GM3844AS8T
SOP-8
100 Units / Tube
GM3844AS8R
SOP-8
2,500 Units / Tape & Reel
GM3845AD8T
DIP-8
60 Units / Tube
GM3845AS8T
SOP-8
100 Units / Tube
GM3845AS8R
SOP-8
2,500 Units / Tape & Reel
GM3842A, GM3843A
GM3844A, GM3845A
CURRENT MODE PWM CONTROLLER
Absolute Maximum Ratings
PARAMETER
Symbol
RATINGS
UNITS
VCC
30
V
Output Current, Source or Sink *
IO
±1
A
Input Voltage (analog inputs pins 2, and 3)
VI
- 0.3 to + 5.5
V
Maximum Power Dissipation (TA= 25°C)
PD
1.0
W
ISINK(E.A.)
10
mA
TA
- 40 to 125-
℃
- 65 to 150
℃
260
℃
Supply Voltage (low impedance source)
Error Amp Output Sink Current
Operating Ambient Temperature Range
Storage Temperature
Lead Temperature (soldering 10 sec.)
* Maximum Package Power Dissipation Limits must be observed.
Block Diagram
7
Internal
Bias
U.V.L.O.
5V
VREF
VREF
8
VCC
36V
EN
5
GND
VREF
Good Logic
Error Amp
R
1V
PWM
Latch
R
1
COMP
6
OUTPUT
S
4
3
T
Oscillator
5
GND
GM384x V1.00
CURRENT
SENSE
RT/CT
2R
2
VFB
7 V
CC
Current
Sense
3
GM3842A, GM3843A
GM3844A, GM3845A
CURRENT MODE PWM CONTROLLER
Electrical Characteristics (TA = 0°C to 70°C, *VCC=15V, CT=3.3nF, RT=10k , unless otherwise
specified)
Parameter
Symbol
Condition
Min
Typ
Max
Unit
4.9
5.0
5.1
V
Reference Section
Reference output
Voltage
VREF
TJ= 25°C, IREF= 1mA
Line Regulation
∆VREF-V
12V < VCC < 25V
6.0
20
mV
Load Regulation
∆VREF-I
1mA < IREF < 20mA
6.0
25
mV
-100
-180
mA
52
57
KHz
0.05
1
%
Short CirCuit output
Current
ISC
TA=25°C
f
TJ= 25°C
Oscillator Section
Oscillation Frequency
Frequency Change
with Voltage
Oscillator Amplitude
47
∆f/∆VCC 12V < VCC < 25V
V(osc)
(Peak to Peak)
1.6
V
VFB = 3V
-0.1
-2
µA
2.58
V
Error Amplifier Section
Input Bias Current
IBIAS
Input Voltage
Open Loop Voltage
Gain
Power Supply
Rejection Ratio
VI(EA)
VPIN1 = 2.5V
2.42
2.5
AVOL(EA)
2V < VO < 4V
65
90
dB
60
70
dB
2
7
mA
PSRR(EA) 12V < VCC < 25V
Output Sink Current
ISINK(EA)
VPIN2 = 2.7V, VPIN1 = 1.1V
Output Source Current
Isource(EA)
VPIN2 = 2.3V, VPIN1 = 5V
-0.5
-1.0
mA
5.0
6.0
V
High Output Voltage
VOH(EA)
VPIN2 = 2.3V, RL =15K to GND
Low Output Voltage
VOL(A)
VPIN2 = 2.7V, RL =15K to GND
0.8
1.1
V
3.0
3.15
V/V
VPIN1 = 5V (Note 1)
1.0
1.1
V
70
Current Sense Section
Current Sense Input
Voltage Gain
Maximum Input Signal
GV
VI(MAX)
(Note 1 and 2)
2.85
Supply Voltage
Rejection
SVR
12V < VCC < 25V (Note 1)
Input Bias Current
IBIAS
VPIN3 = 3V
-3.0
-10
ISINK = 20mA
0.8
0.4
ISINK = 200mA
1.4
2.2
dB
µA
GM384x V1.00
Output Section
4
Low Output Voltage
High Output Voltage
VOL
VOH
V
ISource= -20mA
13
13.5
Isource = -200mA
12
13
V
Rise Time
tr
TJ = 25°C, CL = 1nF (Note 3)
45
150
ns
Fall Time
tf
TJ = 25°C, CL = 1nF (Note 3)
35
150
ns
GM3842A, GM3843A
GM3844A, GM3845A
CURRENT MODE PWM CONTROLLER
Electrical Characteristics (TA = 0°C to 70°C, VCC=15V, CT=3.3nF, RT=10k , unless otherwise
specified)
Parameter
Symbol
Condition
Min
Typ
Max
GM3842A, GM3844A
14.5
16.0
17.5
GM3843A, GM3845A
7.8
8.4
9.0
GM3842A, GM3844A
8.5
10
11.5
GM3843A, GM3845A
7.0
7.6
8.2
GM3842A, GM3844A
95
97
100
GM3843A, GM3845A
47
45
50
Unit
Undervoltage Lockout Section
Start Threshold
Minimum Operating
Voltage (after turn on)
VTH(ST)
V
V
VOPR(MIN)
PWM Section
Maximum Duty Cycle
Minimum Duty Cycle
D(MAX)
%
D(MIN)
0
%
0.17
0.3
mA
13
17
mA
Total Standby Current
Start-Up Current
IST
Operating Supply
Current
ICC(OPR)
Zero Voltage
VZ
VPIN3 = VPIN2 = 0V
ICC = 25mA
30
35
V
GM384x V1.00
* Adjust VCC above the Startup threshold before setting to l5 V.
Note 1: Parameter measured at trip point of latch with VPIN2 = 0V
Note 2: Gain defined as A = VPIN1 / VPIN3; 0V< VPIN3 < 0.5V
Note 3: These parameters, although quaranteed, are not 1005 tested in production
5
GM3842A, GM3843A
GM3844A, GM3845A
CURRENT MODE PWM CONTROLLER
Typical Performance Characteristics
%
RT (K)
VCC = 15V
CT = 1000pF
50
CT = 200pF
CT = 500pF
CT = 1nF
20
50
30
CT = 5nF
20
10
CT = 10pF
10
CT = 2nF
CT = 2nF
5
CT = 1000pF
2 VCC = 15V
1 TA = 25°C
20
2
50
100
200
300 500
fosc (KHZ)
Figure 1. Timing Resistor vs. Oscillator Frequency
Dmax
(%)
1
10
20
30
50 100
(dB)
80
80
60
70
40
60
20
50
0
RT (k
Figure 3. Maximum Output Duty Cycle vs.
Timing Resistor (GM3842A/43A)
1
2
3
5
200
300 500
-20
l0
VCC = 15V
VO = 2V to 4V
RL = 100K
TA = 25°C
l00
lk
l0k
l00k
lM
Figure 4. Error Amp Open-Loop Gain vs.
Frequency
ISC
(mA)
VTH
(V)
VCC = 15V
1.0
0.8
l00
TA = 125°C
90
VCC = 15V
TA = 25°C
0.6
80
0.4
70
0.2
60
50
0
2
6
4
VO (V)
6
Vsat
(V)
-1
0
25
50
75
l00 T (°C)
A
Figure 6. Reference Short Circuit Current vs.
Temperature
ICC
(mA)
Source Saturation
(Load to Ground)
ISENSE = 0V
VFB = 0V
RT = 10K
TA = 25°C
CT = 3.3nF
VCC = 15V
-2
20
50μs Pulsed Load 120Hz Rate
3
2
l
10
Sink Saturation
(Load to V+)
5
0
0
0
200
400
600
Io (mA)
Figure 7. Output Saturation Voltage vs.
Load Current TA= 25°C
GM3842A / 44A
l5
GM3843A / 45A
GM384x V1.00
Figure 5. Current Sense Input Threshold vs.
Error Amp Output Voltage
fosc (kHz)
Figure 2. Output Dead-Time vs. Oscillator Frequency
VCC = 15V
90 CT = 3.3nF
TA = 25°C
40
CT = 200pF
5
CT = 10pF
10
CT = 500pF
CT = 1nF
CT = 5nF
0
10
20
30
VCC (V)
Figure 8. Supply Current vs. Supply Voltage
GM3842A, GM3843A
GM3844A, GM3845A
CURRENT MODE PWM CONTROLLER
Package Outline Dimensions – SO 8
0.189 - 0.197
(4.800 - 5.004)
0.228 - 0.244
(5.791 - 6.198)
0.016 - 0.050
(0.406 - 0.270)
D
0.014 - 0.020
(0.356 - 0.508)
0.050
(1.270)
TYP
0.150 - 0.157
(3.810 - 3.988)
0.053 - 0.059
(1.346 - 1.753)
SEATING PLAN
0.004 - 0.010
(0.012 - 0.254)
8.0
MAX
0.008 - 0.010
(0.203 - 0.254)
Package Outline Dimensions – DIP 8
0.250 +/- 0.005
(6.350 +/- 0.127)
0.370 - 0.400
(9.474 - 10.150)
0.300 - 0.320
(7.620 - 8.128)
0.06
(1.524)
0.125 - 0.140
(3.175 - 3.556)
0.045 +/- 0.015
(1.143 +/- 0.183)
0.108 +/- 0.003
(0.457 +/- 0.076)
0.100 +/- 0.010
(2.540 +/- 0.254)
J
0.009 - 0.010
(0.299 - 0.381)
95 +/- 5
GM384x V1.00
0.145 - 0.200
(3.683 - 5.080)
7
GM3842A, GM3843A
GM3844A, GM3845A
CURRENT MODE PWM CONTROLLER
Ordering Number
GM 3842 A
APM Gamma
Micro
Circuit
Type
Revision
S8
R
Package
Type
Shipping Type
R: Taping & Reel
T: Tube
GM384x V1.00
S8: SO 8
D8: DIP 8
8
1
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