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AP3842/3/4/5
High Performance Current Mode PWM Controller Features
* * * * * * * * * * *
General Description
The AP3842/3/4/5 family of control ICs provides the necessary features to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count. Internally implemented circuits include under voltage lockout featuring start-up current less than 0.5 mA, a precision reference trimmed for accuracy at the error amp input, logic to insure latched operation, a PWM comparator which also provides current limit control, and a totem pole output stage designed to source or sink high peak current. The output stage, suitable for driving N-Channel MOSFETs, is low in the off-state. Differences between members of this family are the under-voltage lockout thresholds and maximum duty cycle ranges. The AP3842 and AP3844 have UVLO thresholds of 16V(on) and 10V(off), ideally suited for off-line applications. The corresponding thresholds for the AP3843 and AP3845 are 8.5V and 7.6V. The AP3842 and AP3843 can operate to duty cycles approaching 100%. A range of the zero to < 50% is obtained by the AP3844 and AP3845 by the addition of an internal toggle flip flop which blanks the output off every other clock cycle.
Optimized for Off-Line and DC to DC Converters Low Start-Up Current (0.5mA) Automatic Feed Forward Compensation Pulse-by-Pulse Current Limiting Enhanced Load Response Characteristics Under-Voltage Lockout (UVLO) with Hysteresis Double Pulse Suppression High Current Totem Pole Output Internally Trimmed Bandgap Reference Current Mode Operation to 500KHZ Low Ro Error Amplifier
Pin Connections
PDIP-8L, SOP-8L
Top View
COMP. VFB ISENSE RT/CT 1 2 3 4 8 7 6 5 VREF VI OUTPUT GROUND
Ordering Information
AP 384X X X X
Part No. 2:3842 3:3843 4:3844 5:3845
Package S8:SOP-8L N8:PDIP-8L
Lead Free
Packing
Blank: Tube Blank : Normal L : Lead Free Package A : Taping
This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sale of the product.
Rev.1.0 Oct.11, 2004 1/8
AP3842/3/4/5
High Performance Current Mode PWM Controller Block Diagram ( toggle flip flop used only in AP3844 and AP3845 )
Vi 7 36V GROUND 5 16V UVLO S/R 8 INTERNAL BIAS
5V REF
VREF 5V 50mA
2.50V
VREF GOOD LOGIC T 2R R S R 1V CURRENT SENSE COMPARATOR PWM LATCH
6
RT/CT
4
OUTPUT
OSC. ERROR AMP.
2 VFB COMP CURRENT SENSE 1 3
AP384X
Absolute Maximum Ratings
Symbol Vi Vi Io Eo Ptot Ptot Tstg TL Parameter Supply Voltage (low impedance source) Supply Voltage (li < 30mA) Output Current Output Energy (capacitive load) Analog Inputs (pins2,3) Error Amplifier Output Sink Current Power Dissipation at Tamb 500C (PDIP8) Power Dissipation at Tamb 250C (SOP8) Storage Temperature Range Lead Temperature (soldering 10s) Value 36 Self Limiting 0.7 5 -0.3 to 5.5 10 1.25 800 -65 to 150 260 Unit V A J V mA W mW o C o C
*Notes: 1. All voltages are with respect to pin 5, all currents are positive into the specified terminal.
Electrical Characteristics
(Unless otherwise stated, these specifications apply for
0Tamb70 C for AP384X ; Vi = 15V(note 5); RT = 10K;CT = 3.3nF)
o
Symbol
Parameter
Test Conditions
AP384X Min. Typ. Max.
Unit
REFERENCE SECTION VREF Output Voltage VREF Line Regulation VREF Load Regulation VREF/T Temperature Stability Total Output Variation eN ISC
Tj = 250C I0=1mA 4.90 5.00 5.10 V 12VVi25V 2 20 mV 1mAIo20mA 3 25 mV (Notes 2) 0.2 0.4 mV/0C Line, Load, Temperature (Notes 2) 4.82 5.18 V 10Hzf10KHz Tj=250C (Notes 50 V Output Noise Voltage 2) 0 Long Term Stability Tamb=125 C, 1000Hrs (Notes 2) 5 25 mV Output Short Circuit current -85 -120 mA
Anachip Corp. www.anachip.com.tw 2/8
Rev.1.0 Oct.11, 2004
AP3842/3/4/5
High Performance Current Mode PWM Controller Electrical Characteristics(Continued)
(Unless otherwise stated, these specifications apply for 0Tamb70 C for AP384X ; Vi = 15V(note 5); RT = 10K;CT = 3.3nF)
o
Symbol
Parameter
Test Conditions Tj=250C (Notes 6, 7) 12VVi25V TMINTambTMAX (Notes 2) VPIN4 Peak to Peak 0 Tj=25 C VPIN4=2V VPIN1=2.5V VFB=5V 0VV04V Tj=25oC 12VVi25V VPIN2=2.7V VPIN1=1.1V VPIN2=2.3V VPIN1=5V VPIN2=2.3V; RL=15K to ground VPIN2=2.7V; RL=15K to pin 8 (Notes3&Notes4) VPIN1=5V (Notes3) 12Vi25V (Notes3)
AP384X Min. Typ. Max. 49 52 0.2 0.5 1.6 8.3 55 1
Unit KHz % % V mA V A dB MHz dB mA mA V V V/V V dB A ns V V V V ns ns V V V V V % % % mA mA V
OSCILLATOR SECTION fs Oscillator Frequency Voltage Stability Temperature Stability V4 Amplitude Discharge Current ERROR AMP SECTION V2 Feedback Input Voltage Ib Input Bias Current AVOL B Unity Gain Bandwidth Supply Voltage Rejection SVRR Ratio IO Output Sink Current IO Output Source Current VOUT High VOUT Low CURRENT SENSE SECTION Gv Gain V3 Maximum Input Signal Supply Voltage Rejection SVRR Ratio Ib Input Bias Current Delay to Output OUTPUT SECTION VOL VOH Output Low Level Output High Level
7.8
8.8
2.42 2.50 2.58 -0.1 -2 65 90 0.7 1 60 2 -0.5 5 70 6 -0.8 7 0.8 3 1 70 -2 150 -10 300 0.4 2.2
1.1 3.15 1.1
2.85 0.9
Tr Rise Time Tf Fall Time VOLS UVLO Saturation UNDER-VOLTAGE LOCKOUT SECTION Start Threshold Min Operating Voltage After Turn-on PWM SECTION Maximum Duty Cycle Minimum Duty Cycle TOTAL STANDBY CURRENT Ist Ii Viz Start-up Current Operating Supply Current Zener Voltage
ISINK= 20mA ISINK= 200mA ISOURCE= 20mA ISOURCE= 200mA Tj=250C CL=1nF (Notes2) Tj=250C CL=1nF (Notes2) Vcc = 6V ; Isink = 1mA 3842/4 3843/5 3842/4 3843/5 3842/3 3844/5
13 12
0.1 1.6 13.5 13.5 50 50 0.1 16 8.4 10 7.6 96 48
150 150 1.1 17.5 9 11.5 8.2
14.5 7.8 8.5 7.0 94 47
50 0 0.5 17
Vi=14V,3842/4 ; Vi=6.5V 3843/5 VPIN2=VPIN3=0V Ii=25mA
0.3 30 12 36
Anachip Corp. www.anachip.com.tw 3/8
Rev.1.0 Oct.11, 2004
AP3842/3/4/5
High Performance Current Mode PWM Controller
Notes2.These parameters, although guaranteed, are not 100% tested in production. 3.Parameter measured at trip point of latch with VPIN2=0. 4.Gain defined as: VPIN1 ; 0VPIN30.8V A= VPIN3 5.Adjust Vi above the start threshold before setting at 15V. 6.Output frequency equals oscillator frequency for the AP3842 and AP3843. 7.Output frequency is one and half oscillator frequency for the AP3844 and AP3845.
Figure 1 : Error Amp Configuration.
2.5V 0.8 mA
Zf Zf
2 COMP 1
VFB
Error amp can source or sink up to 0.5mA
Figure 2 : Under Voltage Lockout.
ON/OFF COMMAND TO REST OF IC
I
CC
V
i
7
AP3842 AP3843 AP3844 AP3845
V
<17 mA
ON
16V 10V
8.4V 7.6V
<1 mA
V
VOFF
OFF VON
VCC
During Under-Voltage Lockout, the output driver is biased to sink minor amounts of current. Pin 6 should be shunted to ground with a bleeder resistor to prevent activating the power switch with extraneous leakage currents. Figure 3 : Current Sense Circuit.
ERROR AMP
IS
2R
COMP R C 3 1 CURRENT SENSE
R
1V
CURRENT SENSE COMPARATOR
Rs
5
GND
Anachip Corp. www.anachip.com.tw 4/8
Rev.1.0 Oct.11, 2004
AP3842/3/4/5
High Performance Current Mode PWM Controller
Peak current(is) is determined by the formula 1.0V IS max RS A small RC filter may be required to suppress switch transients. Figure 4.
VREF RT/CT GROUND
8
RT
4
CT
5
for RT > 5K f=
1.72 RTCT
Figure 5 : Open Loop Test Circuit.
VREF R
T A 1 COMP.
VFB VREF
4.7K
2N2222 8 7 6 5 0.1 uF
Vi
100K ERROR AMP. ADJUST 2 1K
ISENSE Vi
5K
AP3842
3 4
ISENSE
ADJUST 4.7K
OUTPUT
0.1 uF
TW 1K OUTPUT
R T/CT
GROUND
C
GROUND T
High peak currents associated with capacitive loads necessitate careful grounding techniques. Timing and bypass apacitors should be connected close to pin 5 in a single point ground. The transistor and 5 K potentiometer are used to sample the oscillator waveform and apply an adjustable ramp to pin 3. Figure 6 : Shutdown Techniques.
1K
B VREF
1 COMP 330K 500K SHUTDOWN TO CURRENT SENSE RESISTOR 3
I
SENSE SHUTDOWN
Anachip Corp. www.anachip.com.tw 5/8
Rev.1.0 Oct.11, 2004
AP3842/3/4/5
High Performance Current Mode PWM Controller
Shutdown of the AP3842 can be accomplished in two ways; either raise pin 3 above 1V or pull pin 1 below a voltage two diode drops above ground. Either one of them causes the output of the PWM comparator to be high (refer to block diagram). The PWM latch is reset dominant so that the output will remain low until the next clock cycle after the shutdown condition at pins 1 and/or 3 is removed. In one example, an externally latched shutdown may be accomplished by adding an SCR that will be reset by cycling Vi below the lower UVLO threshold. At this point the reference turns off, allowing the SCR to reset. Figure 7 : Slope Compensation.
Uref
8 0.1uF RT
RT/CT 4 CT R1 R2 Isense 3 C Rsense Isense
AP3842/3
A fraction of the oscillator ramp can be resistively summed with the current sense signal to provide slope compensation for converters requiring duty cycles over 50%. Note that capacitor, C, forms a filter with R2 to suppress the leading edge switch spikes.
Anachip Corp. www.anachip.com.tw 6/8
Rev.1.0 Oct.11, 2004
AP3842/3/4/5
High Performance Current Mode PWM Controller Package Diagrams
(1) PDIP-8L (Plastic Dual-in-line Package)
D
E-PIN O0.118 inch
E1
E 15 (4X) PIN #1 INDENT O0.025 DEEP 0.006-0.008 inch
7 (4X) eB A2 A
C
L
B S e B1 B2
Symbol A A1 A2 B B1 B2 C D E E1 e L eB S
Dimensions in millimeters Min. Nom. Max. 5.33 0.38 3.1 3.30 3.5 0.36 0.46 0.56 1.4 1.52 1.65 0.81 0.99 1.14 0.20 0.25 0.36 9.02 9.27 9.53 7.62 7.94 8.26 6.15 6.35 6.55 2.54 2.92 3.3 3.81 8.38 8.89 9.40 0.71 0.84 0.97
A1
Dimensions in inches Min. Nom. Max. 0.210 0.015 0.122 0.130 0.138 0.014 0.018 0.022 0.055 0.060 0.065 0.032 0.039 0.045 0.008 0.010 0.014 0.355 0.365 0.375 0.300 0.313 0.325 0.242 0.250 0.258 0.100 0.115 0.130 0.150 0.330 0.350 0.370 0.028 0.033 0.038
Anachip Corp. www.anachip.com.tw 7/8
Rev.1.0 Oct.11, 2004
AP3842/3/4/5
High Performance Current Mode PWM Controller
(2) SOP-8L (JEDEC Small Outline Package)
E
H
L VIEW "A"
D 7 (4X) A2 A
0.015x45
7 (4X)
A1
e
B y
C
VIEW "A"
Symbol A A1 A2 B C D E e H L y
Dimensions In Millimeters Min. Nom. Max. 1.40 1.60 1.75 0.10 0.25 1.30 1.45 1.50 0.33 0.41 0.51 0.19 0.20 0.25 4.80 5.05 5.30 3.70 3.90 4.10 1.27 5.79 5.99 6.20 0.38 0.71 1.27 0.10 0O 8O
Dimensions In Inches Min. Nom. Max. 0.055 0.063 0.069 0.040 0.100 0.051 0.057 0.059 0.013 0.016 0.020 0.0075 0.008 0.010 0.189 0.199 0.209 0.146 0.154 0.161 0.050 0.228 0.236 0.244 0.015 0.028 0.050 0.004 0O 8O
Marking Information
Logo Part No. AP384XB YYWW X X 2,3,4,5 Blank: normal L: Lead Free Package ID code: internal Xth Week : 01~52 Year : "01"=2001 "02"=2002 ~
Anachip Corp. www.anachip.com.tw 8/8
Rev.1.0 Oct.11, 2004

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