Intel Microcontroller, 80C196NU, 8XC196NP Generating an External Reset, Internal Reset Circuitry

Models: Microcontroller 80C196NU 8XC196NP

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MINIMUM HARDWARE CONSIDERATIONS

The following events will reset the device (see Figure 11-8):

an external device pulls the RESET# pin low

the CPU issues the reset (RST) instruction

the CPU issues an idle/powerdown (IDLPD) instruction with an illegal key operand

The following paragraphs describe each of these reset methods in more detail.

Reset State

Clock

Internal External

VCC

Internal

Reset

Signal

RST Instruction

IDLPD Invalid Key

Machine

Trigger

Stop

CLR

Q

SET

RRST

RESET#

~200 Ω

Q1

See the datasheet for minimum and maximum RRST values.

A2416-01

Figure 11-8. Internal Reset Circuitry

11.6.1 Generating an External Reset

To reset the device, hold the RESET# pin low for at least one state time after the power supply is within tolerance and the oscillator has stabilized. When RESET# is first asserted, the device turns on a pull-down transistor (Q1) for 16 state times. This enables the RESET# signal to function as the system reset.

11-9

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Intel Microcontroller, 80C196NU, 8XC196NP manual Generating an External Reset, Internal Reset Circuitry