Rainbow Electronics MAX6871 - Manual (Page 14)

Set the primary and secondary threshold voltages for
each voltage-detector input with registers 00h–0Bh.
Each primary threshold voltage must be an undervolt-
age threshold. Configure each secondary threshold
voltage as an undervoltage or overvoltage threshold
(see register 0Ch). Set the threshold range for each
voltage detector with register 0Dh.
High Voltage Input (IN1)
IN1 offers threshold voltages of +2.5V to +13.2V in
50mV increments, or +1.25V to +7.625V in 25mV incre-
ments. Use the following equations to set the threshold
voltages for IN1:
where V
TH
is the desired threshold voltage and x is the
decimal code for the desired threshold (Table 2). For
the +2.5V to +13.2V range, x must equal 214 or less,
otherwise the threshold exceeds the maximum operat-
ing voltage of IN1.
Bipolar Voltage Input (IN2)
IN2 offers negative thresholds from -2.5V to -15.25V in
50mV increments, or from -1.25V to -7.625V in 25mV
increments. Alternatively, IN2 offers positive thresholds
from +2.5V to +15.25V in 50mV increments, or +1.25V
to +7.625V in 25mV increments. Use the following
equations to set the threshold voltages for IN2:
x
V V
V
for V to V range
TH = + +
− .
.
. .
1 25
0 025
1 25 7 625
x
V V
V
for V to V range
TH = + +
− .
.
. .
2 5
0 05
2 5 13 2
MAX6870/MAX6871
EEPROM-Programmable Hex/Quad
Power-Supply Sequencers/Supervisors with ADC
14 ______________________________________________________________________________________
Table 1. Programmable Features (continued)
FEATURE DESCRIPTION
General-Purpose Logic
Inputs (GPI1–GPI4)
• Active high or active low logic levels
• Configure GPI_ as inputs to watchdog timers or programmable output stages
Watchdog Timers
• Clear dependent on any combination of one GPI_ input and one programmable output, a GPI_ input
only, or a programmable output only
• Initial watchdog timeout period of 6.25ms, 25ms, 100ms, 400ms, 1.6s, 6.4s, 25.6s, or 102.4s
• Normal watchdog timeout period of 6.25ms, 25ms, 100ms, 400ms, 1.6s, 6.4s, 25.6s, or 102.4s
• Watchdog enable/disable
• Initial watchdog timeout period enable/disable
Auxiliary Inputs
(AUXIN1, AUXIN2)
• Monitored by the internal 10-bit ADC
Manual Reset Input
(MR)
• Forces PO_ into the active output state when MR = GND
• PO_ deassert after MR releases high and the PO_ timeout period expires
• PO_ cannot be a function of MR only
Margining Input
(MARGIN)
• Holds PO_ in existing state or asserts PO_ to a programmed output state, independent of changes in
monitored inputs or watchdog timers, when MARGIN = GND
• Overrides MR when both assert at the same time
Reference Input
(REFIN)
• Internal +1.25V reference voltage
• Goes high-impedance when internal reference selected
• External reference voltage input from +1.225V to +1.275V
• Sets ADC voltage range
10-Bit ADC*
• Monitors IN_, AUXIN1, and AUXIN2
• Completes conversion of all eight inputs in 200ms
• Reference voltage sets ADC range
• Read ADC data from SMBus/I
2 C interface
Write Disable • Locks user EEPROM based on PO_
Configuration Lock • Locks configuration EEPROM
*ADC does not control programmable outputs.