CM3842 [ETC]
CURRENT MODE PWM CONTROLLER; 电流模式PWM控制器
| 型号： | CM3842 |
| 厂家： | 
ETC |
| 描述： | CURRENT MODE PWM CONTROLLER |
| 文件： | 总12页 (文件大小：411K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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 ꢀ
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.
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.
APPLICATIONS
PIN CONFIGURATION
ꢀ
ꢀ
ꢀ
Off-line flyback or forward converters.
DC-to-DC buck or boost converter.
Monitor Power Supply
VREF
VCC
COMP
VFB
ISENSE
RT/CT
OUTPUT
GND
8-Pin PDIP
(Top View)
AVAILABLE OPTIONS
Device
Start-UP
Voltage
VREF
VCC
COMP
VFB
Hysteresis Max. Duty Cycle
CM3842
CM3843
16V
6V
< 100%
< 100%
ISENSE
OUTPUT
RT/CT
GND
8.4V
0.8V
8-Pin S.O.I.C.
(Top View)
2001/06/27 Advanced
Champion Microelectronic Corporation
Page 1
CM3842/3843
CURRENT MODE PWM CONTROLLER
ORDERING INFORMATION
Part Number
CM3842/43CP
CM3842/43CS
Temperature Range
Package
0℃ to 70℃
0℃ to 70℃
8-Pin PDIP(P08)
8-Pin SOIC(S08)
BLOCK DIAGRAM
VCC
7
5
Internal
Bias
36V
U.V.L.O.
VREF
5V
VREF
EN
GND
8
VREF
Good Logic
PWR
VC
7
Current
Sense
Error Amp
2R
PWM
Latch
VFB
2
1
R
S
1V
R
OUTPUT
6
COMP
CURRENT
SENSE
3
T
PWR
GND
4
RT/CT
5
Oscillator
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
CM3842/3843
CURRENT MODE PWM CONTROLLER
ABSOLUTE MAXIMUM RATINGS
Supply voltage, VCC
35V
Output current, IO
± 1A
Analog inputs, VI
-0.3V to 6.3V
10mA
Error amp output sink current, ISINK(EA)
Power dissipation (TA = 25OC), PD
Maximum junction temperature TJ
Storage temperature range
Lead temperature (soldiering, 10 seconds)
1W
150OC
-65OC to 150OC
260OC
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:
95OC/W
Thermal Resistance-Junction to Ambient, θJA
165OC/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.
2001/06/27 Advanced
Champion Microelectronic Corporation
Page 3
CM3842/3843
CURRENT MODE PWM CONTROLLER
RECOMMENDED OPERATING CONDITIONS
Parameter
Symbol
Units
Min.
Typ.
Max.
Supply Voltage
Input Voltage
V/ V
VI,RT/CT
VI,ISENSE/VFB
VO, Output
ICC
30
V
V
0
0
5.5
Output Voltage
Supply Current
30
25
V
mA
mA
mA
nF
Average Output Current
Reference Output Current
Timing Capacitor
IO
200
-20
I
C
1
0
Oscillator Frequency
f
100
500
70
KHz
OC
Operating Free-air Temperature
T
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, these specifications apply over the operating ambient temperature for CM384X with 0OC ≤
TA ≤70OC; 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.
CM384X
Parameter
Symbol
Test Conditions
Units
Min. Typ. Max.
Line Regulation
O
12V ≤ V≤ 25V,T= 25 OC
6
20
mV
mA
Short Ciruit Output Current
Oscillator Section
I
T= 25OC
-30
47
-100 -180
Oscillation Frequency
Frequency Change with Voltage
f
T= 25OC
52
57
KHz
%
12V ≤ VCC ≤ 25V
0.2
1.0
Frequency Change with Temperature
(note 8)
T
MIN ≤ TA ≤ TMAX
5
%
V
Peak-to-peak Amplitude At RT/CT
VOSC
1.7
Current Sense Section
Gain (note 9 & 10)
AVOL
2.85 3.00
3.15
1.1
V/V
V
Maximum Input Signal (note 9)
VI(MAX)
COMP = 5V
0.9
1.0
2001/06/27 Advanced
Champion Microelectronic Corporation
Page 4
CM3842/3843
CURRENT MODE PWM CONTROLLER
ELECTRICAL CHARACTERISTICS (Continued)
Error Amplifier Section
Input Bias Current
Input Voltage
I
V
G
-0.1
-2
µA
V
COMP = 2.5V
2.42 2.50 2.58
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
2V ≤ V≤ 4V
65
0.7
60
2
90
1
dB
MHz
dB
mA
mA
V
UGBW T= 25 OC
PSRR
ISINK
12V ≤ VCC ≤ 25V
VFB = 2.7V, COMP = 1.1V
70
7
ISOURCE VFB = 2.3V, COMP = 5.0V
-0.5
5
-1.0
6
VOH
VOL
VFB = 2.3V, RL = 15KΩ to GND
VFB = 2.7V, RL = 15KΩ to VREF
0.7
1.1
V
ISINK = 20mA
0.1
1.4
0.4
2.2
Output Low Level
Output High Level
VOL
V
V
ISINK = 200mA
ISOURCE = 20mA
TJ = 25 OC, CL = 1nF
O
13
13.5
50
VOH
Rise Time (note 8)
tr
150
ns
Start Threshold
VTH(ST)
V
V
Min. Operating Voltage
CM3842/43
94
97
100
0
Maximum Duty Cycle
%
%
Minimum Duty Cycle
Total Standby Current
CM3842
0.2
0.5
14
0.35
1.0
17
Startup Current
mA
CM3843
Operating Supply Current
Zener Voltage
I
V
V= I= 0V
I= 25mA
mA
V
30
35
note 7: Adjust VCC above the start threshold before setting at 15V
note 8: These parameters, although guaranteed, are not 100% tested in production prior to shipment
note 9: Parameters are measured at trip point of latch with VFB = 2V
note 10: Gain is measured between ISENSE and COMP with the input changing from 0V to 0.8V
2001/06/27 Advanced
Champion Microelectronic Corporation
Page 5
CM3842/3843
CURRENT MODE PWM CONTROLLER
APPLICATION INFORMATION
Error
Amp
2R
1V
R
Current
COMP
ISENSE
Sense
Comparator
Rf
RS
Cf
GND
Fig. 1. Current Sense Circuit
Peak current (IS) is set by: IS(MAX) = 1V/RS
VREF
2.5V
0.5mA
Error
Amp
RT
CT
RT/CT
GND
VFB
Zi
COMP
Zf
Fig. 3. Oscillator Section
Fig. 2. Error Amplifier Configuration - the
amplifier can source or sink up to 0.5mA
1.72
For RT < 5K, f =
RTCT
VREF
RT
VCC
2N2222
4.7K
100K
VREF
VCC
COMP
VFB
0.1µF
1K
1K,
1W
Error AMP
5K
ISENSE
Adjust
Adjust
ISENSE
RT/CT
Output
GND
Output
GND
4.7K
0.1µF
CT
Fig. 4. Open-loop laboratory test fixture: Careful grounding techniques are necessary for high peak
currents 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
2001/06/27 Advanced
Champion Microelectronic Corporation
Page 6
CM3842/3843
CURRENT MODE PWM CONTROLLER
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
RT
0.1µF
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.
2001/06/27 Advanced
Champion Microelectronic Corporation
Page 7
CM3842/3843
CURRENT MODE PWM CONTROLLER
TYPICAL CHARACTERISTICS
Oscillator Frequency and Frequemcy Variation
1,000,000
100,000
10,000
1,000
100
1uF
0.1uF
0.01uF
0.001uF
10
1
10
100
1000
RT-Timing Resistance (unit: k ohm)
2001/06/27 Advanced
Champion Microelectronic Corporation
Page 8
CM3842/3843
CURRENT MODE PWM CONTROLLER
8-PIN PLASTIC DIP
5
4
8
INCHES
MILLIMETERS
B
MIN TYP MAX MIN TYP MAX
0.355 0.365 0.400 9.02 9.27 10.16
0.240 0.250 0.280 6.10 6.35 7.11
1
A
B
C
D
F
A
-
-
0.210
-
-
-
-
-
5.33
-
0.018
0.060
0.100
-
-
-
-
0.46
1.52
2.54
-
-
-
L
F
-
C
G
H
J
-
-
J
K
0.050
0.008
0.090 1.27
0.015 0.20
2.29
0.38
M
H
G
D
-
-
K
L
0.115 0.130 0.150 2.92 3.30 3.81
0.300 BSC.
7º
7.62 BSC.
7º 15º
M
-
15º
-
8-PIN PLASTIC S.O.I.C
.
INCHES
MILLIMETERS
MIN TYP MAX MIN TYP MAX
A
A
B
C
D
F
0.183
0.144
0.068
0.010
0.015
-
-
-
-
-
0.202 4.65
0.163 3.66
0.074 1.73
0.020 0.25
0.035 0.38
-
5.13
4.14
1.88
0.51
0.89
-
B
P
-
F
-
-
G
K
D
G
J
0.050 BSC
0.050 BSC
L
C
0.007
-
-
-
-
-
0.010 0.19
-
-
-
-
-
0.25
0.25
5.21
8º
M
SEATING PLAN
K
L
0.005
0.189
-
0.010 0.13
0.205 4.80
J
M
P
8º
-
0.228
0.244 5.79
6.20
2001/06/27 Advanced
Champion Microelectronic Corporation
Page 9
CM3842/3843
CURRENT MODE PWM CONTROLLER
8-PIN PLASTIC S.O.I.C. CARRIER DIMENSIONS
D
T2
MILLIMETERS
A
B
DD
D1
330 ± 1
100 ± 1
1.55 ± 0.1
1.5 ± 0.25
C
B
A
+0.5
-1.0
2.2 ± 1
C
13.0
Po
4.0 ± 0.1
D
T1
T2
Wc
Wt
P
P1
Ao
Bo
Ko
t
2.0 ± 0.1
6.4 ± 0.1
12.5 ± 0.5
2.0 ± 0.2
T1
5.2 ± 0.1
+0.3
-0.1
12.0
2.1 ± 0.1
DD
Po
P1
E
t
9.3 TYP.
0.30 ± 0.013
F
8.0 ± 0.1
1.75 ± 0.1
5.5 ± 0.1
Wc
Wt
Bo
E
D1
F
P
Ko
Ao
2001/06/27 Advanced
Champion Microelectronic Corporation
Page 10
CERAMIC/SURGE
ABSORBER
SHANGHAI,CHINA
DIODES LAB
DC POWER LAB
TAIPEI,TAIWAN
CERAMIC/PZT
SHINCHU,TAIWAN
HANGZHOU,CHINA
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