Rainbow Electronics MAX16068 - Manual (Page 11)

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MAX16068
6-Channel, Flash-Configurable System Manager
with Nonvolatile Fault Registers
When in the monitoring state, and when EN falls below
the undervoltage threshold, a register bit, ENRESET
(r20h[2]), is set to a ‘1.’ This register bit latches and must
be cleared through software. This bit indicates if RESET
asserted low due to EN going under the threshold. The
POR state of ENRESET is ‘0.’ The bit is only set on a fall-
ing edge of the EN comparator output or the software
enable bit. If operating in latch-on fault mode, toggle
EN or toggle the software enable bit to clear the latch
condition and restart the device once the fault condition
has been removed.
Set r73h[2] to ‘1’ to enable monitoring functionality.
Faults are not recorded when the device is in margining
mode. Set r73h[2] to ‘0’ for normal functionality.
Voltage Monitoring
The MAX16068 features an internal 10-bit ADC that mon-
itors the MON_ voltage inputs. An internal multiplexer
cycles through each of the enabled inputs, taking less
than 24Fs for a complete monitoring cycle. Each acquisi-
tion takes approximately 4Fs. At each multiplexer stop,
the 10-bit ADC converts the analog input to a digital
result and stores the result in a register. ADC conversion
results are stored in registers r00h–r0Bh (see Table 2).
Use the SMBus or JTAG serial interface to read ADC
conversion results.
The MAX16068 provides six inputs, MON1–MON6, for
voltage monitoring. Each input-voltage range is pro-
grammable in registers r43h–r44h (see Table 3). When
MON_ configuration registers are set to ’11,’ MON_ volt-
ages are not monitored and the multiplexer does not stop
at these inputs, decreasing the total cycle time. These
inputs cannot be configured to trigger fault conditions.
The two programmable thresholds for each monitored
voltage include an overvoltage and an undervoltage
threshold. See the Faults section for more information
on setting overvoltage and undervoltage thresholds. All
voltage thresholds are 8 bits wide. The 8 MSBs of the
10-bit ADC conversion result are compared to these
overvoltage and undervoltage thresholds.
For any undervoltage or overvoltage condition to be
monitored and any faults detected, the MON_ input must
be assigned to monitoring mode. Inputs that are not
enabled are not converted by the ADC; they contain the
last value acquired before that channel was disabled.
The ADC conversion result registers are reset to 00h at
boot-up. These registers are not reset when a reboot
command is executed.
To temporarily disable voltage monitoring during volt-
age margining conditions, set r73h[2] to ‘1’ to enable
margining mode functionality. Faults (except for faults
triggered by EXTFAULT being pulled low externally) are
not recorded when the device is in margining mode, but
the ADC continues to run and conversion results con-
tinue to be available. Set r73h[2] back to ‘0’ for normal
functionality.
Table 2. ADC Conversion Results (Read Only)
REGISTER ADDRESS BIT RANGE DESCRIPTION
00h [7:0] MON1 result (MSB)
01h [7:6] MON1 result (LSB)
02h [7:0] MON2 result (MSB)
03h [7:6] MON2 result (LSB)
04h [7:0] MON3 result (MSB)
05h [7:6] MON3 result (LSB)
06h [7:0] MON4 result (MSB)
07h [7:6] MON4 result (LSB)
08h [7:0] MON5 result (MSB)
09h [7:6] MON5 result (LSB)
0Ah [7:0] MON6 result (MSB)
0Bh [7:6] MON6 result (LSB)