TMP89FS60 datasheet(93/410 Pages) TOSHIBA

93 / 410 page

Page 79

TMP89FS60

RA000

6. Power-on Reset Circuit

The power-on reset circuit generates a reset when the power is turned on. When the supply voltage is lower than

the detection voltage of the power-on reset circuit, a power-on reset signal is generated.

6.1

Configuration

The power-on reset circuit consists of a reference voltage generation circuit and a comparator.

The supply voltage divided by ladder resistor is compared with the voltage generated by the reference voltage gen-

eration circuit by the comparator.

Figure 6-1 Power-on Reset Circuit

6.2

Function

When power supply voltage goes on, if the supply voltage is equal to or lower than the releasing voltage of the

power-on reset circuit, a power-on reset signal is generated and if it is higher than the releasing voltage of the power-

on reset circuit, a power-on reset signal is released.

When power supply voltage goes down, if the supply voltage is equal to or lower than the detecting voltage of the

power-on reset circuit, a power-on reset signal is generated.

Until the power-on reset signal is generated, a warm-up circuit and a CPU is reset.

When the power-on reset signal is released, the warm-up circuit is activated. The reset of the CPU and peripheral

circuits is released after the warm-up time that follows reset release has elapsed.

Increase the supply voltage into the operating range during the period from detection of the power-on reset release

voltage until the end of the warm-up time that follows reset release. If the supply voltage has not reached the operat-

ing range by the end of the warm-up time that follows reset release, the TMP89FS60 cannot operate properly.

VDD

Power-on reset signal

Comparator

Reference voltage

generation circuit

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