existing state while system-level testing occurs. Leave

MARGIN unconnected or connect to BP if unused. An

internal 10µA current source pulls MARGIN to BP.

MARGIN overrides MR if both are asserted at the

same time. The state of RESET, OV, and WDO does not

change while MARGIN = GND.

RESET, OV, and WDO Outputs

The MAX6887/MAX6888 feature three active-low open-

drain outputs: RESET, OV, and WDO. After power-up or

overvoltage/undervoltage conditions, RESET and OV

remain in their active states until their timeout periods

expire and no undervoltage/overvoltage conditions are

present (see Figure 2).

OV asserts when any monitored input is above its over-

voltage threshold and remains asserted until all inputs

are below their thresholds and its respective 25µs time-

out period expires. Connect OV to MR to bring RESET

low during an overvoltage condition. OV requires a

pullup resistor (unless connected to MR).

RESET asserts when any monitored input is below its

undervoltage threshold or MR is asserted. RESET

remains asserted for 200ms after all assertion-causing

conditions have been cleared. Configure RESET to

assert when the watchdog timer expires by connecting

WDO to MR. RESET requires a pullup resistor.

WDO asserts when the watchdog timer expires. See

the Configuring the Watchdog Timer section for a com-

plete description. WDO requires a pullup resistor.

Configuring the Watchdog Timer

A watchdog timer monitors microprocessor (µP) soft-

ware execution for a stalled condition and resets the µP

if it stalls. Connect the watchdog timer output WDO to

the reset input or a nonmaskable interrupt of the µP.

The watchdog timer features independent initial and

normal watchdog timeout periods of 102.4s and 1.6s,

respectively.

Hex/Quad, Power-Supply Supervisory Circuits

_______________________________________________________________________________________

9

Table 2. MAX6888 Threshold Options

UV THRESHOLDS (V)

OV THRESHOLDS (V)

PART

IN1

IN2

IN3

IN4

IN1

IN2

IN3

IN4

MAX6888AETE

4.620

3.060

2.310

1.670

5.360

3.540

2.680

1.930

MAX6888BETE

4.620

3.060

2.310

0.557

5.360

3.540

2.680

0.643

MAX6888CETE

4.620

3.060

1.670

0.557

5.360

3.540

1.930

0.643

MAX6888DETE

3.060

2.310

1.670

1.390

3.540

2.680

1.930

1.610

MAX6888EETE

3.060

2.310

1.670

0.557

3.540

2.680

1.930

0.643

MAX6888FETE

3.060

2.310

1.390

0.557

3.540

2.680

1.610

0.643

MAX6888GETE

3.060

2.310

0.557

0.557

3.540

2.680

0.643

0.643

MAX6888HETE

3.060

1.670

0.557

0.557

3.540

1.930

0.643

0.643

MAX6888QETE

0.527

0.527

0.527

0.527

0.673

0.673

0.673

0.673

MAX6888IETE

4.380

2.880

2.190

1.580

5.620

3.700

2.810

2.020

MAX6888JETE

4.380

2.880

2.190

0.527

5.620

3.700

2.810

0.673

MAX6888KETE

4.380

2.880

1.580

0.527

5.620

3.700

2.020

0.673

MAX6888LETE

2.880

2.190

1.580

1.310

3.700

2.810

2.020

1.680

MAX6888METE

2.880

2.190

1.580

0.527

3.700

2.810

2.020

0.673

MAX6888NETE

2.880

2.190

1.310

0.527

3.700

2.810

1.680

0.673

MAX6888OETE

2.880

2.190

0.527

0.527

3.700

2.810

0.673

0.673

MAX6888PETE

2.880

1.580

0.527

0.527

3.700

2.020

0.673

0.673

MAX6888RETE

0.557

0.557

0.557

0.557

0.643

0.643

0.643

0.643