MAX6884/MAX6885
EEPROM-Programmable, Hex
Power-Supply Supervisory Circuits
16 ______________________________________________________________________________________
External Voltage-Divider
To achieve thresholds from 0.1667V to 1.0167V in
3.3mV increments, program the respective input voltage
detector for high impedance and use an external volt-
age-divider (see Figure 2). Set voltage-detector inputs
for high impedance by programming bits R10h[5:0].
Design the resistor voltage-divider to scale the input
voltage to between 0.1667V and 1.0167V at the input of
the device. In this way, voltages higher than 5.8V and in
between the 10mV and 20mV steps can be monitored.
Program R00h through R0Eh to adjust the thresholds
between 0.1667V and 1.0167V in 3.3mV steps.
AUXIN (MAX6884 Only)
The AUXIN high-impedance analog input is intended to
monitor additional system voltages not required for
reset purposes. The internal 10-bit ADC converts the
voltage at AUXIN and stores the data in the ADC regis-
ters (see Table 3). AUXIN does not affect any of the
programmable outputs. The AUXIN input accepts
power-supply voltages or other system voltages scaled
to the 1.25V ADC input voltage range.
MR
Program RESET and/or UV/OV to assert when manual
reset input MR is brought low (see Tables 5 and 6).
Outputs programmed to assert when MR is brought low
remain asserted after MR is brought high for their
respective programmed timeout periods. An internal
10µA current source pulls MR to V
DBP
. Leave MR
unconnected or connect to DBP if unused.
MARGIN
MARGIN allows system-level testing while power sup-
plies exceed the normal ranges. Drive MARGIN low to
hold the programmable outputs in their existing state
while system-level testing occurs. Leave MARGIN
unconnected or connect to DBP if unused. An internal
10µA current source pulls MARGIN to V
DBP
. The inter-
nal ADC continues to convert voltages while MARGIN is
low. The state of each programmable output does not
change while MARGIN = GND. MARGIN overrides MR
if both are asserted at the same time.
REFIN (MAX6884 Only)
The MAX6884/MAX6885 feature an internal 1.25V volt-
age reference. The voltage reference sets the threshold
of the voltage detectors and provides a reference volt-
age for the internal ADC. Program the MAX6884 to use
an internal or external reference by programming bit
R16h[7] (see Table 5). Leave REFIN unconnected
when using the internal reference. REFIN accepts an
external reference in the 1.225V to 1.275V range.
