Low-Power Dual-/Triple-Voltage SC70 µP

Supervisory Circuits

10

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Detailed Description

Supply Voltages

The MAX6736–MAX6745 µP supervisory circuits main-

tain system integrity by alerting the µP to fault condi-

tions. These devices are optimized for systems that

monitor two or three supply voltages. The reset output

Threshold Levels

The MAX6736/MAX6737/MAX6740/MAX6741/MAX6743/

MAX6744 input voltage threshold combinations are indi-

cated by a two-letter code in Table 1. The MAX6738/

MAX6739/MAX6742/MAX6745 input voltage thresholds

are indicated by a one-letter code in Table 2. Contact the

factory for the availability of other voltage thresholds.

Reset Output

The MAX6736–MAX6745 provide an active-low reset out-

put (

RESET). RESET is asserted when the voltage at

level, RSTIN drops below the threshold, or

MR is pulled

low. Once reset is asserted, it stays low for the reset time-

threshold before the reset timeout period is completed,

the internal timer restarts. The MAX6736/MAX6738/

MAX6740/MAX6741/MAX6742 have open-drain reset out-

puts, while the MAX6737/MAX6739/MAX6743/MAX6744/

MAX6745 have push-pull reset outputs (Figure 1).

The MAX6740/MAX6741/MAX6742 include a

RESET

output with a manual reset detect function. The open-

drain

RESET output has an internal 50k

Ω pullup to

pulled to GND and remains low for at least the manual

reset timeout period after the external GND pulldown is

GND

GND

GND

POK1

GND

GND

MR

RESET

SWITCH

BOUNCE

SWITCH

BOUNCE

Figure 1. Timing Diagram