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TD3842A / 3843A / 3844A / 3845A
HIGH PERFORMANCE CURRENT MODE PWM CONTROLLERS
DESCRIPTION The TD3842A / 3843A/384 4A/3845A are fixed frequency current-mode PWM controller. They are specially designed for Off - Line and DC-to-DC converter applications with minimum external components. These integrated circuits feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier. current sensing comparator, and a high current totempole output Ideally suited for driving a power MOSFET. Protection circuity Includes built in under-voltage lockout and current limiting. The TD3842A and TD3844A have UVLO thresholds of 16V (on) and 10V (off) The TD 3843A and TD3845A are 8.4V (on) and 7.6V (off) The TD3842A and TD3843A can operate within 100% duty cycle. The TD3844A and TD3845A can operate with 50% duty cycle. FEATURES • Low Start Up Current • Maximum Duty Clamp • UVLO With Hysteresis • Operating Frequency Up To 500KHz
SOP-8
DIP-8
BLOCK DIAGRAM
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Note 1: Toggle flip flop us ed only in 3844A a nd 3845A.
PIN CONNECTIONS
Compensation Voltage Feedback Current Sense RT/CT
1
8
Vref VCC Output Gnd
2
7
3
6
4
5
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TD3842A / 3843A / 3844A / 3845A
MA XIMUM R AT ING S
R ating B ias and Driver Voltages (Zero S eries Impedance, s ee als o Total Device s pec) Total P ower S upply and Zener C urrent Output C urrent, S ource or S ink (Note 1) Output E nergy (C apacitive Load per C ycle) C urrent S ens e and Voltage F eedback Inputs E rror Amp Output S ink C urrent P ower Dis s ipation and T hermal C haracteris tics D S uffix, P las tic P ackage Maximum P ower Dis s ipation @ T A = 25 °C T hermal R es is tance, J unction-to-Air N S uffix, P las tic P ackage Maximum P ower Dis s ipation @ T A = 25 °C T hermal R es is tance, J unction-to-Air Operating J unction Temperature Operating Ambient Temperature S torage Temperature R ange 1. Maximum P ackage power dis s ipation limits mus t be obs erved. S ymbol VCC, VC (I C C + I Z ) IO W V in IO Value 30 30 1.0 5.0 - 0.3 to + 5.5 10 Unit V mA A µJ V mA
PD R θJ A PD R θJ A TJ TA Ts tg
862 145 1.25 100 + 150 0 to + 70 - 65 to + 150
mW °C /W W °C /W °C °C °C
E L E C T R IC A L C HA R A C T E R IS T IC S (V C C = 15 V, [Note 2], R T = 10 k, C T = 3.3 nF, T A = T low to T high [Note 3], unles s otherwis e noted.)
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C harac teris tic s R E F E R E NC E S E C T ION
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S ymbol
TD3842A /43A /44A /45A Min Typ Max Unit
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R eference Output Voltage (I O = 1.0 mA, T J = 25 °C ) Line R egulation (V C C = 12 V to 25 V ) Load R egulation (I O = 1.0 mA to 20 mA) Temperature S tability Total Output Variation over Line, Load, Temperature Output Nois e Voltage (f = 10 Hz to 10 kHz, T J = 25 °C ) Long Term S tability (T A = 125 °C for 1000 Hours ) Output S hort C ircuit C urrent OS C IL L ATOR S E C T ION F requency T J = 25 °C T A = T low to T high F requency C hange with Voltage (V C C = 12 V to 25 V) F requency C hange with Temperature T A = T low to T high Os cillator Voltage S wing (P eak±to±P eak) Dis charge C urrent (V os c = 2.0 V ) T J = 25 °C T A = T low to T high
V ref R egline R egload TS V ref Vn S IS C fos c
4.9 4.82 - 30
5.0 2.0 3.0 0.2 50 5.0 - 85
5.1 20 25 5.18 - 180
V mV mV mV / °C V µV mV mA
kHz 47 46 7.5 7.2 52 0.2 5.0 1.6 8.4 57 60 1.0 9.3 9.5 % % V mA
∆fos c/∆V ∆fos c/∆T V os c I dis chg
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TD3842A / 3843A / 3844A / 3845A
E R R OR A MP L IF IE R S E C T ION TD 3842A /43A /44A /45A C harac teris tic s Voltage F eedback Input (V O = 2.5 V ) Input B ias C urrent (V F B = 2.7 V ) Open Loop Voltage G ain (V O = 2.0 V to 4.0 V ) Unity G ain B andwidth (T J = 25 °C ) P ower S upply R ejection R atio (V C C = 12 V to 25 V ) Output C urrent S ink (V O = 1.1 V, V F B = 2.7 V ) S ource (V O = 5.0 V, V F B = 2.3 V ) Output Voltage S wing High S tate (R L = 15 k to ground, V F B = 2.3 V ) Low S tate (R L = 15 k to V ref, V F B = 2.7 V ) S ymbol VFB I IB AV OL BW PSR R I S ink I S ource V OH V OL Min 2.42 65 0.7 60 2.0 -0.5 5.0 Typ 2.5 -0.1 90 1.0 70 12 -1.0 6.2 0.8 Max 2.58 -2.0 V 1.1 Unit V µA dB MHz dB mA
2. Adjus t V C C above the S tartup thres hold before s etting to 15 V. 3. Low duty cycle puls e techniques are us ed during tes t to maintain junction temperature as clos e to ambient as pos s ible. T low = 0 °C for TD3842A/43A/44A/45A T high = +70 °C for TD3842A/43A/44A/45A
E L E C T R IC A L C HA R A C T E R IS T IC S (V C C = 15 V, [Note 4], R T = 10 k, C T = 3.3 nF, T A = T low to T high [Note 5],
unles s otherwis e noted.) C harac teris tic s C UR R E NT S E NS E S E C T ION C urrent S ens e Input Voltage G ain (Notes 6 & 7) Maximum C urrent S ens e Input T hres hold (Note 6) P ower S upply R ejection R atio V C C = 12 to 25 V (Note 6) Input B ias C urrent P ropagation Delay (C urrent S ens e Input to Outp.