Pin Description; Lm809; General Description; Features - Hitachi 42PD3200A Service Manual

12.13.3. Pin Description

12.14. LM809

12.14.1. General Description

The LM809/810 microprocessor supervisory circuits can be used to monitor the power supplies in
microprocessor and digital systems. They provide a reset to the microprocessor during power-up, power-
down and brown-out conditions. The function of the LM809/810 is to monitor the VCC supply voltage and
assert a reset signal whenever this voltage declines below the factory-programmed reset threshold. The
reset signal remains asserted for 240ms after VCC rises above the threshold. The LM809 has an active-low
RESET output, while the LM810 has an active-high RESET output. Seven standard reset voltage options are
available, suitable for monitoring 5V, 3.3V, and 3V supply voltages. With a low supply current of only 15μA,
the LM809/810 are ideal for use in portable equipment.

12.14.2. Features

•
Precise monitoring of 3V, 3.3V, and 5V supply voltages
•
Superior upgrade to MAX809/810
•
Fully specified overtemperature
• 140ms min. Power-On Reset pulse width, 240ms typical
Active-low RESET Output(LM809)
Active-high RESET Output(LM810)
•
Guaranteed RESET Output valid for VCC 1V
•
Low Supply Current, 15μA typ
•
Power supply transient immunity

12.14.3. Pinning

19