manualshive.com logo in svg

ST UC2842B, Руководство пользователя, Страница: 12 / 15

Поделиться
Скачать
ST UC2842B Скачать руководство пользователя страница 12

D95IN354

+

R

BIAS

OSC

C

R

+

-

+

-

EA

R

2R

R

S

Q

8

4

2

1

5

1mA

1V

+

-

5V

ref

1M

Ω

Figure 24: Soft-Start Circuit 

D95IN355

+

R

BIAS

OSC

C

R

+

-

+

-

EA

R

2R

R

S

Q

8

4

2

1

5

1mA

1V

+

-

5V

ref

R2

R1

V

Clamp

+

-

Comp/Latch

7

R

S

V

CC

Q1

V

in

7

6

5

BC109

V

CLAMP 

= 

·

R

1

R

1

 + R

2

where 0 <V

CLAMP

 <1V

I

pk(max)

 =

V

CLAMP

R

S

Figure 25: Soft-Start and Error Amplifier Output Duty Cycle Clamp. 

UC2842B/3B/4B/5B - UC3842B/3B/4B/5B

12/15

Содержание UC2842B

Страница 1: ...amp input logic to insure latched operation a PWM comparatorwhich also providescurrent limit control and a totem pole output stage designed to source or sink high peak current The output stage suitabl...

Страница 2: ...to 150 C TL Lead Temperature soldering 10s 300 C PIN FUNCTIONS No Function Description 1 COMP This pin is the Error Amplifier output and is made available for loop compensation 2 VFB This is the inve...

Страница 3: ...1 0 2 1 fOSC T Frequency Change with Temp TA Tlow to Thigh 1 0 5 VOSC Oscillator Voltage Swing peak to peak 1 6 1 6 V Idischg Discharge Current VOSC 2V TJ 25 C TA Tlow to Thigh 7 8 7 5 8 3 8 8 8 8 7 8...

Страница 4: ...High Level ISOURCE 20mA 13 13 5 13 13 5 V ISOURCE 200mA 12 13 5 12 13 5 V VOLS UVLO Saturation VCC 6V ISINK 1mA 0 1 1 1 0 1 1 1 V tr Rise Time Tj 25 C CL 1nF 2 50 150 50 150 ns tf Fall Time Tj 25 C CL...

Страница 5: ...gle point ground The transistor and 5K potentiometerareusedtosampletheoscillator waveform and apply an adjustable ramp to pin 3 10K 20K 30K 50K 100K 200K 300K 500K fOSC KHz 1 2 5 10 20 50 D95IN333 CT...

Страница 6: ...Vi 15V VO 2V to 4V RL 100K TA 25 C Gain Phase Figure 6 Error Amp Open Loop Gain and Phase vs Frequency 0 2 4 6 VO V 0 0 0 2 0 4 0 6 0 8 1 0 Vth V D95IN338 Vi 15V TA 40 C TA 125 C TA 25 C Figure 7 Curr...

Страница 7: ...43 45 UCX842 44 RT 10K CT 3 3nF VFB 0V ISense 0V TA 25 C D95IN342 Figure 11 Supply Current vs Supply Voltage Figure 12 Output Waveform Figure 13 Output Cross Conduction 5V REG OSCILLATOR PWM CLOCK 8 4...

Страница 8: ...MAND TO REST OF IC 7 0 5mA 17mA ICC VCC VOFF VON D95IN346 Figure 17 Current Sense Circuit ERROR AMPL 2R R 1V CURRENT SENSE COMPARATOR 1 CURRENT SENSE COMP C RS R 3 5 GND IS D95IN347 Peak current is is...

Страница 9: ...PE CT RT VREG 8 RT CT ISENSE 4 3 5 GND D95IN348 Figure 19 Isolated MOSFET Drive and Current Transformer Sensing 7 6 COMP LATCH ISOLATION BOUNDARY D95IN349 5 0Vref VCC Q S R 3 R RS NS C Vin Q1 NP VGS W...

Страница 10: ...51 EA Ri 1mA Rd R 2R 5 Cf Rf 1 2 From VO 2 5V EA RP 1mA Rd R 2R 5 Cf Rf 1 2 From VO 2 5V Error Amp compensation circuit for stabilizing any current mode topology except for boost and flyback converter...

Страница 11: ...3 External Duty Cycle Clamp and Multi Unit Synchronization D95IN352 EA R 2R 5 RT 1 2 EXTERNAL SYNC INPUT The diode clamp is required if the Sync amplitude is large enough to cause the bottom side of C...

Страница 12: ...art Circuit D95IN355 R BIAS OSC C R EA R 2R R S Q 8 4 2 1 5 1mA 1V 5Vref R2 R1 VClamp Comp Latch 7 RS VCC Q1 Vin 7 6 5 BC109 VCLAMP R1 R1 R2 where 0 VCLAMP 1V Ipk max VCLAMP RS Figure 25 Soft Start an...

Страница 13: ...010 C 0 25 0 5 0 010 0 020 c1 45 typ D 1 4 8 5 0 0 189 0 197 E 5 8 6 2 0 228 0 244 e 1 27 0 050 e3 3 81 0 150 F 1 3 8 4 0 0 15 0 157 L 0 4 1 27 0 016 0 050 M 0 6 0 024 S 8 max 1 D and F do not includ...

Страница 14: ...1 65 0 045 0 065 b 0 356 0 55 0 014 0 022 b1 0 204 0 304 0 008 0 012 D 10 92 0 430 E 7 95 9 75 0 313 0 384 e 2 54 0 100 e3 7 62 0 300 e4 7 62 0 300 F 6 6 0 260 I 5 08 0 200 L 3 18 3 81 0 125 0 150 Z 1...

Страница 15: ...ice This publication supersedes and replaces all information previously supplied STMi croelectronics products are not authorized for use as critical components in life support devices or systems witho...

Отзывы:

Нет отзывов