CS8101YT5G 데이터 시트보기 (PDF) - ON Semiconductor

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CS8101YT5G

Micropower 5.0 V, 100 mA Low Dropout Linear Regulator with RESET and ENABLE

ON Semiconductor 

CS8101

The RESET output is an open collector NPN transistor,

controlled by a low voltage detection circuit. The circuit is

functionally independent of the rest of the IC thereby

guaranteeing that the RESET signal is valid for VOUT as low

as 1.0 V.

VOUT

CS8101

RRST

5.0 V to mP

and System

Power

COUT

RESET

CRST

to mP

RESET

Port

Figure 5. RC Network for RESET Delay

An external RC network on the lead (Figure 5) provides

a sufficiently long delay for most microprocessor based

applications. RC values can be chosen using the following

formula:

ƪ ƫ ǒ Ǔ RTOTCRST +

−tDelay

ln

VT*VOUT

VRST*VOUT

where:

RRST = RESET Delay resistor

RIN = mP port impedance

RTOT = RRST in parallel with RIN

CRST = RESET Delay capacitor

tDelay = desired delay time

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

VT = RESET threshold.

The circuit depicted in Figure 6 lets the microprocessor

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

on the mP 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

regulator’s output is enabled. When the drive current is

removed, the voltage on the ENABLE lead rises, the output

is switched off and the IC moves into Sleep mode where it

draws 50 mA (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.

Table 1. Logic Control of CS8101 Output

Microprocessor

I/O Drive

Switch

ENABLE

Output

ON

Closed

LOW

ON

Open

LOW

ON

OFF

Closed

LOW

ON

Open

HIGH

OFF

The I/O port of the microprocessor typically provides

50 mA to Q1. In automotive applications the SWITCH is

connected to the ignition switch.

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