CS52843 datasheet(4/6 Pages) CHERRY

4 / 6 page

Figure 1: Startup voltage for the CS52843.

Undervoltage Lockout

During Undervoltage Lockout (Figure 1), the output driv-

er is biased to sink minor amounts of current. The output

should be shunted to ground with a resistor to prevent

activating the power switch with extraneous leakage cur-

rents.

PWM Waveform

To generate the PWM waveform, the control voltage from

the error amplifier is compared to a current sense signal

which represents the peak output inductor current (Figure

2). An increase in VCC causes the inductor current slope to

increase, thus reducing the duty cycle. This is an inherent

feed-forward characteristic of current mode control, since

the control voltage does not have to change during

changes of input supply voltage.

VCC

VON =8.4V

VOFF = 7.6V

ON/OFF Command

to reset of IC

<15mA

<500µA

VON

VOFF

ICC

VCC

Test Circuit Open Loop Laboratory Test Fixture

VREF

VCC

VOUT

1kΩ

0.1µF

VREF

VCC

VOUT

Gnd

VFB

Sense

OSC

COMP

5kΩ

100kΩ

4.7kΩ

1kΩ

Error Amp

Adjust

4.7kΩ

Sense

Adjust

2N2222

Gnd

Typical Performance Characteristics

100

200

700

10k

RT (Ω)

500

400

300

100

.0005

.001

.002

.003

.005

.01

.02

.03

.04

800

900

CT (µF)

700

600

500

400

300

200

100

.05

RT =1.5kΩ

RT =680Ω

RT =10kΩ

Oscillator Frequency vs CT

Oscillator Duty Cycle vs RT

Circuit Description

CS52843 데이터시트(PDF) 4 Page - Cherry Semiconductor Corporation

CS52843 데이터시트(HTML) 4 Page - Cherry Semiconductor Corporation

Html Pages

1 2 3 4 5 6

데이터시트 다운로드

링크 URL