CM3843 Datasheet PDF - Champion

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CM3843
Champion

Part Number CM3843
Description CURRENT MODE PWM CONTROLLER
Page 11 Pages


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CM3842/3843
CURRENT MODE PWM CONTROLLER
GENERAL DESCRIPTION
FEATURES
The CM3842/43 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 typ. start-up current, allowing an
efficient bootstrap supply voltage design. The U.V.L.O.
thresholds for the CM3842 are 16V (on) and 10V (off)
which are ideal for off-line applications. The
corresponding typical threshold for the CM3843 are
8.4V (on) and 7.6V (off). The CM3842/43 can operated
within 100% duty cycle.
Low Start-Up current ( typ. 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
8-Pin S.O.I.C.
APPLICATIONS
PIN CONFIGURATION
! Off-line flyback or forward converters.
! DC-to-DC buck or boost converter.
! Monitor Power Supply
AVAILABLE OPTIONS
Device
Start-UP
Voltage
Hysteresis Max. Duty Cycle
CM3842 16V
6V
< 100%
CM3843 8.4V
0.8V
< 100%
COMP
VFB
ISENSE
RT/CT
VREF
VCC
OUTPUT
GND
8-Pin PDIP
(Top View)
COMP
VFB
ISENSE
RT/CT
VREF
VCC
OUTPUT
GND
8-Pin S.O.I.C.
(Top View)
2001/06/27 Advanced
Champion Microelectronic Corporation
Page 1



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CM3842/3843
CURRENT MODE PWM CONTROLLER
ORDERING INFORMATION
Part Number
CM3842/43CP
CM3842/43CS
Temperature Range
0to 70
0to 70
Package
8-Pin PDIP(P08)
8-Pin SOIC(S08)
BLOCK DIAGRAM
VREF
8
Internal
Bias
5V EN
VREF
U.V.L.O.
36V
7 VCC
5 GND
VFB 2
COMP 1
CURRENT
SENSE
RT/CT 4
3
VREF
Good Logic
Error Amp
2R
R
Oscillator
Current
Sense
C
1V
R
PWM
Latch
S
T
7 PWR
VC
OUTPUT
6
PWR
5 GND
Note 1 :VCC and PWR VC are internally connected for 8 pin packages.
Note 2 :PWR GND and GND are internally connected for 8 pin packages.
Note 3 :U.V.L.O. is 16V for 3842 and 8.4V for 3843.
Note 4 :Hysteresis is 6V for 3842 and 0.8V for 3843.
2001/06/27 Advanced
Champion Microelectronic Corporation
Page 2



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CM3842/3843
CURRENT MODE PWM CONTROLLER
ABSOLUTE MAXIMUM RATINGS
Supply voltage, VCC
Output current, IO
Analog inputs, VI
Error amp output sink current, ISINK(EA)
Power dissipation (TA = 25 OC), PD
Maximum junction temperature TJ
Storage temperature range
Lead temperature (soldiering, 10 seconds)
35V
± 1A
-0.3V to 6.3V
10mA
1W
150OC
-65OC to 150OC
260 OC
Note 5: Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground.
Currents are positive into, negative out of the specified terminal.
THERMAL DATA
PDIP PACKAGE:
Thermal Resistance-Junction to Ambient, θJA
SOIC PACKAGE:
Thermal Resistance-Junction to Ambient, θJA
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.
95 OC/W
165 OC/W
2001/06/27 Advanced
Champion Microelectronic Corporation
Page 3



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CM3842/3843
CURRENT MODE PWM CONTROLLER
RECOMMENDED OPERATING CONDITIONS
Parameter
Supply Voltage
Input Voltage
Output Voltage
Supply Current
Average Output Current
Reference Output Current
Timing Capacitor
Oscillator Frequency
Operating Free-air Temperature
Symbol
VCC / VC
VI,RT/CT
VI,ISENSE/VFB
VO, Output
ICC
IO
IO(REF)
CT
fOSC
TA
Recommended Operating
Min.
Typ.
Max.
30
0 5.5
0 30
25
200
-20
1
100 500
0 70
Units
V
V
V
mA
mA
mA
nF
KHz
OC
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, these specifications apply over the operating ambient temperature for CM384X 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
Test Conditions
CM384X
Units
Min. Typ. Max.
Reference Section
Reference output Voltage
Line Regulation
Load Regulation
Short Ciruit Output Current
Oscillator Section
Oscillation Frequency
Frequency Change with Voltage
Frequency Change with Temperature
(note 8)
VREF
ISC
TJ = 25 OC, IREF = 1mA
12V VCC 25V,TJ = 25 OC
1mA IREF 20mA
TJ = 25 OC
f TJ = 25 OC
12V VCC 25V
TMIN TA TMAX
Peak-to-peak Amplitude At RT/CT
VOSC
Current Sense Section
Gain (note 9 & 10)
Maximum Input Signal (note 9)
Power Supply Rejection Ratio (note 9)
Input Bias Current
AVOL
VI(MAX)
PSRR
IBIAS
COMP = 5V
12V VCC 25V (note 9)
4.9 5.0 5.1
V
6 20 mV
6 25 mV
-30 -100 -180 mA
47 52 57 KHz
0.2 1.0 %
5%
1.7 V
2.85
0.9
3.00
1.0
70
-3.0
3.15
1.1
-10
V/V
V
dB
µA
2001/06/27 Advanced
Champion Microelectronic Corporation
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