X5328PZF データシートの表示（PDF） - Renesas Electronics

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X5328PZF

CPU Supervisor with 32Kbit SPI EEPROM

Renesas Electronics 

X5328, X5329 (Replaces X25328, X25329)

PRINCIPLES OF OPERATION

Power-On Reset

Application of power to the X5328/X5329 activates a

Power-on Reset Circuit. This circuit goes active at about

1V and pulls the RESET/RESET pin active. This signal

prevents the system microprocessor from starting to

operate with insufficient voltage or prior to stabilization of

the oscillator. When VCC exceeds the device VTRIP

value for 200ms (nominal) the circuit releases

RESET/RESET, allowing the processor to begin execut-

ing code.

Low Voltage Monitoring

During operation, the X5328/X5329 monitors the VCC

level and asserts RESET/RESET if supply voltage falls

below a preset minimum VTRIP. The RESET/RESET sig-

nal prevents the microprocessor from operating in a

power fail or brownout condition. The RESET/RESET

signal remains active until the voltage drops below 1V. It

also remains active until VCC returns and exceeds VTRIP

for 200ms.

VCC Threshold Reset Procedure

The X5328/X5329 has a standard VCC threshold (VTRIP)

voltage. This value will not change over normal operat-

ing and storage conditions. However, in applications

where the standard VTRIP is not exactly right, or for

higher precision in the VTRIP value, the X5328/X5329

threshold may be adjusted.

Setting the VTRIP Voltage

This procedure sets the VTRIP to a higher voltage value.

For example, if the current VTRIP is 4.4V and the new

VTRIP is 4.6V, this procedure directly makes the change.

If the new setting is lower than the current setting, then it

is necessary to reset the trip point before setting the new

value.

To set the new VTRIP voltage, apply the desired VTRIP

threshold to the VCC pin and tie the CS pin and the WP

pin HIGH. RESET/RESET and SO pins are left uncon-

nected. Then apply the programming voltage VP to both

SCK and SI and pulse CS LOW then HIGH. Remove VP

and the sequence is complete.

Figure 1. Set VTRIP Voltage

CS

VP

SCK

VP

SI

Resetting the VTRIP Voltage

This procedure sets the VTRIP to a “native” voltage level.

For example, if the current VTRIP is 4.4V and the VTRIP is

reset, the new VTRIP is something less than 1.7V. This

procedure must be used to set the voltage to a lower

value.

To reset the VTRIP voltage, apply a voltage between 2.7

and 5.5V to the VCC pin. Tie the CS pin, the WP pin, and

the SCK pin HIGH. RESET/RESET and SO pins are left

unconnected. Then apply the programming voltage VP

to the SI pin ONLY and pulse CS LOW then HIGH.

Remove VP and the sequence is complete.

Figure 2. Reset VTRIP Voltage

CS

SCK VCC

VP

SI

FN8132 Rev 2.00

October 16, 2015

Page 4 of 21

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