Interfacing to Other Voltages

for Logic Compatibility

The open-drain RESET output can be used to interface

to a µP with other logic levels. The open-drain output is

connected to a voltage from 0V to 5.5V as shown in

Figure 5. Generally, the pullup resistor connected to

RESET connects to the supply voltage that is being

systems use the open-drain output to level-shift from

the supervisor’s monitored supply to another supply

the device’s ability to sink current at RESET.

Ensuring a Valid

(Push-Pull

RESET)

ity of RESET decreases drastically. The high-imped-

ance CMOS logic inputs connected to RESET can drift

to undetermined voltages. This presents no problems in

most applications, since most µPs and other circuitry

tions where RESET must be valid down to 0, add a pull-

down resistor between the MAX16056/MAX16057

push-pull RESET output and GND. The resistor sinks

any stray leakage currents, holding RESET low (Figure

6). Choose a pulldown resistor that accommodates

leakages, such that RESET is not significantly loaded

and is capable of pulling to GND. The external pull-

down cannot be used with the open-drain RESET out-

put of the MAX16058/MAX16059.

125nA Supervisory Circuits with Capacitor-

Adjustable Reset and Watchdog Timeouts

______________________________________________________________________________________

11

Figure 5. Interfacing with Other Voltage Levels

5V

GND

µP

RESET

100k

Ω

3.3V

MAX16058

MAX16059

GND

RESET

Figure 6. Ensuring RESET Valid to VCC = GND

GND

RESET

2M

Ω

MAX16056

MAX16057