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AMC3842B/43B/44B/45B
www.addmtek.com DESCRIPTION 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 200A 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 Off-line flyback or forward converters. DC-to-DC buck or boost converter. Monitor Power Supply
CURRENT MODE PWM CONTROLLER
FEATURES Low Start-Up current (max. 200A) 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
COMP VFB ISENSE RT/CT VREF VCC OUTPUT GND
8-Pin Plastic DIP (Top View)
AVAILABLE OPTIONS
Device AMC3842B AMC3843B AMC3844B AMC3845B Start-UP Voltage 16V 8.4V 16V 8.4V Hysteresis 6V 0.8V 6V 0.8V Max. Duty Cycle < 100% < 100% < 50% < 50%
COMP NC VFB NC ISENSE NC RT/CT
VREF NC VCC VC OUTPUT GND PWR RT/CT COMP VFB ISENSE VREF VCC OUTPUT GND
14-Pin Plastic S.O.I.C. Surface Mount (Top View)
8-Pin Plastic S.O.I.C. Surface Mount (Top View)
TA (OC) 0 to 70 0 to 70
Note:
ORDER INFORMATION Plastic DIP-8 Plastic SO-14 M 8-pin D 14-pin AMC384XBM AMC384XBD AMC384XBM (Lead Free) AMC384XBD (Lead Free)
DM 8-pin
Plastic SO-8
AMC384XBDM AMC384XBDM (Lead Free)
1. All surface-mount packages are available in Tape & Reel. AMC384XBDMT). 2. The letter "F" is marked for Lead Free process. 1
Append the letter "T" to part number (i.e. AMC384XBDT, or
Copyright (c) 2006 ADDtek Corp.
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AMC3842B/43B/44B/45B
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 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.
(Note 1) 35V 1A -0.3V to 6.3V 10mA 1W 150 OC -65OC to 150OC 260 OC
Currents are positive into,
THERMAL DATA M PACKAGE: Thermal Resistance-Junction to Ambient, JA D PACKAGE: Thermal Resistance-Junction to Ambient, JA DM PACKAGE: Thermal Resistance-Junction to Ambient, JA
Junction Temperature Calculation: TJ = TA + (PD x JA). The JA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow.
95 OC/W 120 OC/W 165 OC/W
Copyright (c) 2006 ADDtek Corp.
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AMC3842B/43B/44B/45B
BLOCK DIAGRAM 7 (12)
Internal Bias U.V.L.O. 5V EN VREF 36V
VCC
VREF
8 (14)
5 (9) GND
VREF Good Logic Error Amp Current Sense 1V R PWM Latch
7 (11) PWR
VC
2R R
VFB
2 (3)
COMP 1 (1) CURRENT SENSE RT/CT
OUTPUT
S
6 (10)
T
3 (5)
PWR
Oscillator
4 (7)
5 (8) GND
( ) are 14 Pin S.O.I.C. pin number
Note 2: Note 3: Note 4: Note 5: Note 6:
VCC and PWR VC are internally connected for 8 pin packages. PWR GND and GND are internally connected for 8 pin packages. U.V.L.O. is 16V for 3842B/44B and 8.4V for 3843B/45B. Hysteresis is 6V for 3842B/44B and 0.8V for 3843B/45B. Toggle flip flop used only in 3844B/45B
Copyright (c) 2006 ADDtek Corp.
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AMC3842B/43B/44B/45B
RECOMMENDED OPERATING CONDITIONS Recommended Operating Conditions Parameter Symbol Min. Typ. Max. VCC / VC 30 VI,RT/CT VI,ISENSE/VFB VO, Output ICC IO IO(REF) CT fOSC TA 0 0 5.5 30 25 200 -20 100 0 500 70 Units V V V mA mA mA nF KHz O C
Supply Voltage Input Voltage
Output Voltage Supply Current Average Output Current Reference Output Current Timing Capacitor Oscillator Frequency Operating Free-air Temperature
1
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 Reference Section Reference output Voltage VREF TJ = 25 OC, IREF = 1mA 12V VCC 25V,TJ = 25 C 1mA IREF 20mA TJ = 25 OC
O
Symbol
Test Conditions
AMC384XB Min. 4.9 Typ. 5.0 6 6 -100 52 0.2 5 1.7 2.85 0.9 3.00 1.0 70 -3.0 3.15 1.1 -10 Max. 5.1 20 25 -180 57 1.0
Units
V mV mV mA KHz % % V V/V V dB A
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
-30 47
TJ = 25 OC 12V VCC 25V TMIN TA TMAX
COMP = 5V 12V VCC 25V (note 9)
Copyright (c) 2006 ADDtek Corp.
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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 Output Low Level Output High Level Rise Time (note 9) Fall Time (note 9) Under-Voltage Lockout Section Start Threshold Min. Operating Voltage
PWM Section
IBIAS VI(EA) GVO UGBW PSRR ISINK ISOURCE VOH VOL
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 = 15K to GND VFB = 2.7V, RL = 15K to VREF ISINK = 20mA ISINK = 200mA ISOURCE = 20mA ISOURCE = 200mA TJ = 25 OC, CL = 1nF TJ = 25 OC, CL = 1nF AMC3842B/44B AMC3843B/45B AMC3842B/44B AMC3843B/45B AMC3842B/43B AMC3844B/45B AMC3842B/44B AMC3843B/45B VFB = ISENSE = 0V ICC = 25mA
2.42 65 0.7 60 2 -0.5 5
-0.1 2.50 90 1 70 7 -1.0 6 0.7 0.1 1.4 13.5 13.0 50 50 16.0 8.4 10 7.6 97 48
-2 2.58
1.1 0.4 2.2
A V dB MHz dB mA mA V V
VOL VOH tr tf
V V
13 12
150 150 17.5 9.0 11.5 8.2 100 50 0.2 0.2 17
ns ns
VTH(ST)
14.5 7.8 8.5 7.0 94 47
V V
Maximum Duty Cycle Total Standby Current Startup Current Operating Supply Current Zener Voltage
Note 7: Note 8: Note 9: Note 10:
Dmax
%
mA mA V
ICC VZ
30
14 35
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 (c) 2006 ADDtek Corp.
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AMC3842B/43B/44B/45B
CHARACTERIZATION CURVES Below characterization curves was referenced by Fig.4
O s cillator D is charge Current vs . Tem perature
9
Maximum Output Duty Cycle vs. Timing Resistor 100
Vcc=15V
8.5
90 80
Dmax 70 (%) 60
Idischg=7.5mA
Vosc=2V
Idischg (mA)
Idischg=8.8mA Vcc=15V Ct=3.3mF TA=25C
8 7.5 7 -50 -25 0 25 50 75 100 125
50 40 0 1 2 3 4 5
6
7
8
TA(C)
RT (K )
C urre nt S e nse Input Thre shol d vs. Error Amp Out put Vol t a ge . 1.2 1 0.8
Vth 0.6 (V) 0.4 TA=125C TA=25C
Error Amp Open-Loop Gain and Phase vs. Frequency 100 80 60
(dB) 40 Phase 90 Vcc=15V Vo=2V to 4V RL=100K 10 100 1K 10K f(Hz) 100K 1M 120 150 180 Gain O 30 60
20 0 -20
0.2 0 0 1 2
TA=-40C
Vcc=15V
3
4
Vo(V)
5
6
7
8
R e fe re nc e Vol t a ge C ha nge vs. S ourc e C urre nt . 60 50 40 30 20 10 0 0 20 40 60 80 100 120
Iref(mA) Copyright (c) 2006 ADDtek Corp. 6 TA=125C TA=25C TA=-40C
Reference Short Circuit Current vs. Temperature. 110 100 90
Isc80 (mA) 70 Vcc=15V RL0.1
Vcc=15V
60 50 -50 -25 0 25 50 75 100 125 150
TA(C) DD019_F -OCTOBER 2006
AMC3842B/43B/44B/45B
APPLICATION INFORMATION
Error Amp
2R R 1V Current Sense Comparator
COMP Rf RS Cf ISENSE GND
Fig. 1. Current Sense Circuit
Peak current (IS) is set by: IS(MAX) = 1V/RS
2.5V Error Amp Zi Zf VFB
0.5mA
VREF RT RT/CT CT GND
COMP
Fig. 3. Oscillator Section Fig. 2. Error Amplifier Configuration - the
amplifier can source or sink up to 0.5mA For RT < 5K, f = 1.72 RTCT
VREF RT 2N2222 100K
COMP VREF VCC
4.7K 1K Error AMP Adjust 4.7K
VCC 0.1F 1K, 1W Output 0.1F GND
VFB
5K ISENSE Adjust
ISENSE Output RT/CT GND
Fig. 4. Open-loop laboratory test fixture: Careful grounding techniques are necessary for high peak currents CT
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 (c) 2006 ADDtek Corp.
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AMC3842B/43B/44B/45B
APPLICATION INFORMATION (continued)
1K
VREF
COMP
Shutdown 330 ISENSE Shutdown 500 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 0.1F RT
RT/CT CT R2 R1 RSENSE C ISENSE
ISENSE
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 (c) 2006 ADDtek Corp.
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AMC3842B/43B/44B/45B
PACKAGE
8-Pin Plastic DIP
INCHES
8 5
MILLIMETERS MAX MIN 9.02 6.10 TYP 9.27 6.35 5.08 0.46 1.52 2.54 0.25 3.30 7.62 BSC. 15 0 7 15 MAX 10.16 7.11 5.33 0.55 1.65 2.29 0.38 3.81
MIN
B
TYP
A
1 4
0.355 0.365 0.400 0.240 0.250 0.280 0.200 0.210
B
A
C
D 0.014 0.018 0.022 0.356
F L
F G
0.045 0.060 0.065 0.100 0.090
1.15 1.27 0.20 2.92
C
H 0.050
K H G D J
J
M
0.008 0.010 0.015 0.115 0.130 0.150 0.300 BSC. 0 7
K L M
8-Pin Plastic S.O.I.C.
INCHES
A
MILLIMETERS MAX 0.202 MIN 4.65 3.66 1.35 0.25 0.38 TYP 3.95 0.41 0.50 1.27 BSC 0.19 0.13 4.80 0 5.79 6.00 0.25 0.25 5.21 8 6.20 MAX 5.13 4.14 1.88 0.51 0.89
MIN A B
B P
TYP -
0.183
0.144 0.156 0.163 0.068 0.074
C
F
D
D G L C SEATING PLAN K M J
0.010 0.016 0.020 0.015 0.020 0.035 0.050 BSC 0.007 0.005 0.189 0 0.010 0.010 0.205 8
F G J K L M P
0.228 0.236 0.244
Copyright (c) 2006 ADDtek Corp.
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AMC3842B/43B/44B/45B
14-Pin Plastic S.O.I.C.
INCHES MIN
A
MILLIMETERS MAX 0.344 0.158 0.069 0.018 0.030 MIN 8.54 3.81 1.35 0.35 0.67 TYP 1.27 BSC 0.19 0.10 4.82 5.79 0.25 0.25 5.21 8 6.20 MAX 8.74 4.01 1.75 0.46 0.77
TYP -
A B
B P
0.336 0.159
C 0.053 D 0.014 F 0.026
F
G
D L C M J
G J K L M P
0.050 BSC 0.007 0.004 0.189 0.228 0.010 0.010 0.205 8 0.244
SEATING PLAN
K
Copyright (c) 2006 ADDtek Corp.
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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 (c) 2006 ADDtek Corp. 11 DD019_F -OCTOBER 2006

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