Microprocessor and Non-Volatile

Memory Supervisory Circuits

10

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Low-Line Output

In internal threshold mode, the low-line comparator

above the reset threshold, and with 15mV of hysteresis.

to the µP, as described in the previous section, when

Reset Function

The MAX792/MAX820 provide both RESET and RESET

outputs. The RESET and RESET outputs ensure that the

µP powers up in a known state, and prevent code-exe-

cution errors during power-up, power-down, or

brownout conditions.

The reset function will be asserted during the following

conditions:

2) MR less than 1.30V typ.

rises above the reset threshold or after MR has

exceeded 1.30V typ.

When reset is asserted, all the internal counters are

reset, the watchdog output (WDO) and watchdog-pulse

output (WDPO) are set high, and the set watchdog-time-

enable transmission gate is also disabled while reset is

asserted; the chip-enable input (CE IN) becomes high

impedance and the chip-enable output (CE OUT) is

MR

RESET

CE IN OV

CE OUT

25

µs MIN

12

µs TYP

15

µs TYP

Figure 2. Manual-Reset Timing Diagram

MAX792

MAX820

MANUAL RESET

OTHER

RESET

SOURCES

9

MR

*

*

*

.

.

.

DIODES NOT REQUIRED ON OPEN-DRAIN OUTPUTS

Figure 3. Diode "OR" connections allow multiple reset sources

MAX792

12

GND

3

LLIN/REFOUT

RESET

RESET

LOW LINE

RESET IN/INT

4

5

2

10

1

TO

µP

TO

µP

TO

µP NMI

Figure 4a. Connection for Internal Threshold Mode

MAX792

GND

TO

µP

TO

µP

TO

µP NMI

2

1

10

RESET IN/INT

LLIN/REFOUT

RESET

RESET

LOW LINE

12

– (R2 + R3)

THROUGH THE VOLTAGE DIVIDED.

3

R3

R2

R1

Figure 4b. Connection for External Threshold Programming Mode