CS51221 Ver la hoja de datos (PDF) - Cherry semiconductor

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componentes Descripción

Fabricante

CS51221

Enhanced Voltage Mode PWM Controller

Cherry semiconductor 

PACKAGE PIN #

16L PDIP & 16L SO Narrow

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

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PIN SYMBOL

FUNCTION

GATE

ISENSE

SYNC

FF

UV

OV

RT/CT

ISET

VFB

COMP

SS

LGnd

VREF

VCC

PGnd

VC

External power switch driver with 1.0A peak capability. Rail to

rail output occurs when the capacitive load is between 470pF

and 10nF.

Current sense comparator input.

Bidirectional synchronization. Locks to highest frequency.

PWM ramp.

Undervoltage protection monitor.

Overvoltage protection monitor.

Timing resistor RT and capacitor CT determine oscillator

frequency and maximum duty cycle, DMAX.

Voltage at this pin sets pulse-by-pulse overcurrent threshold.

Feedback voltage input. Connected to the error amplifier

inverting input.

Error amplifier output.

Charging external capacitor restricts error amplifier output

voltage during the power up or fault conditions.

Logic Ground.

3.3V reference voltage output. Decoupling capacitor can be

selected from 0.01µF to 10µF.

Logic supply voltage.

Output power stage ground.

Output power stage supply voltage.

Block Diagram

VCC

SYNC

RTCT

VFB

UVL

+

-

UV Lockout

Start/Stop

ENABLE VREF = 3.3V

3.3V

3.1V

VREF OK

S

3.0V

VBG

(1.263V) EAMP

2V to 1V Trip Points

OSC

Max Duty Cycle

(Sat Sense)

SS to 1.8V Max

G2

R

COMP

Soft Start Clamp

PWM

Comp

Thermal

Shutdown

2mA(maximum load current) VREF

Low

VC

Sat

Gate

Q

Driver

G1

GATE

Q

13.5V

PGnd

VREF

50µA

LGnd

FF

ISET

ISENSE

DISABLE 150ns

Blank

FF Discharge

G3

ILIM

ON

Max SS

Det

3.0V

(Sat Sense)

VO Off

G4

Latching

Discharge 5µA

SS

OV Monitor

OV

2V

UV Monitor

UV

1V

6

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