CS8101 查看數據表（PDF） - Cherry semiconductor

零件编号

产品描述 (功能)

比赛名单

CS8101

Micropower 5V, 100mA Low Dropout Linear Regulator with RESET and ENABLE

Cherry semiconductor 

VOUT

CS8101

RRST

Circuit Description: continued

based applications. RC values can be chosen using the

following formula:

COUT

5V to mP

and

System

Power

[ ( ) ] RTOTCRST =

ln

ÐtDelay

VT Ð VOUT

VRST Ð VOUT

RESET

CRST

to mP

RESET

Port

Figure 3. RC Network for RESET Delay

An external RC network on the RESET lead (Figure 3) pro-

vides a sufficiently long delay for most microprocessor

where:

RRST = RESET Delay resistor

RIN = µP port impedance

RTOT = RRST in parallel with RIN

CRST = RESET Delay capacitor

tDelay = desired delay time

VRST = VSAT of RESET lead (0.7V @ turn - ON)

VT = RESET threshold

Applications Notes

VBAT

0.1mF

500kW

VIN

VOUT

CS8101

ENABLE

RESET

Gnd

RRST

CRST

VCC

COUT

mP

RESET

I/O Port

SWITCH

Q1

500kW

100kW

100kW

Figure 4. Microprocessor Control of CS8101 using external switching transistor Q1.

The circuit depicted in Figure 4 lets the microprocessor

control its power source, the CS8101 regulator. An I/O

port on the µP and the SWITCH port are used to drive the

base of Q1. When Q1 is driven into saturation, the voltage

on the ENABLE lead falls below its lower threshold. The

regulatorÕs output is enabled. When the drive current is

removed, the voltage on the ENABLE lead rises, the out-

put is switched off and the IC moves into Sleep mode

where it draws 50µA (max).

By coupling these two controls with the ENABLE lead, the

system has added flexibility. Once the system is running,

the state of the SWITCH is irrelevant as long as the I/O

port continues to drive Q1. The microprocessor can turn

off its own power by withdrawing drive current, once the

SWITCH is open. This software control at the I/O port

allows the microprocessor to finish key housekeeping

functions before power is removed.

The logic options are summarized in Table 1.

4

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