Rainbow Electronics MAX16071 - Manual (Page 12)

12-Channel/8-Channel, Flash-Configurable System
Managers with Nonvolatile Fault Registers
MAX16070/MAX16071
12 _____________________________________________________________________________________
When in the monitoring state, a register bit, ENRESET,
is set to a ‘1’ when EN falls below the undervoltage
threshold. 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 falling edge
of the EN comparator output or the software enable bit.
Voltage/Current Monitoring
The MAX16070/MAX16071 feature an internal 10-bit
ADC that monitors the MON_ voltage inputs. An internal
multiplexer cycles through each of the enabled inputs,
taking less than 40Fs for a complete monitoring cycle.
Each acquisition takes approximately 3.2Fs. 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 to
r1Ah (see Table 6). Use the SMBus or JTAG serial inter-
face to read ADC conversion results.
The MAX16070 provides twelve inputs, MON1 to MON12,
for voltage monitoring. The MAX16071 provides eight
inputs, MON1 to MON8, for voltage monitoring. Each
input voltage range is programmable in registers r43h to
r45h (see Table 5). When MON_ configuration registers
are set to ’11,’ MON_ voltages 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 three programmable thresholds for each monitored
voltage include an overvoltage, an undervoltage, and a
secondary warning threshold that can be set in r73h[3]
to be either an undervoltage or overvoltage 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.
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.
Configure the MAX16070/MAX16071 for differential
mode in r46h (Table 5). The possible differential pairs
are MON1/MON2, MON3/MON4, MON5/MON6, MON7/
MON8, MON9/MON10, MON11/MON12 with the first
input always being at a higher voltage than the second.
Use differential voltage sensing to eliminate voltage off-
sets or measure supply current. See Figure 3. In differ-
ential mode, the odd-numbered MON_ input measures
the absolute voltage with respect to GND while the result
of the even input is the difference between the odd and
even inputs. See Figure 3 for the typical differential mea-
surement circuit.
Figure 3. Differential Measurement Connections Figure 4. Current-Sense Amplifier
MAX16070
MAX16071
I
LOAD
LOAD
MON ODD
MON ODD MON EVEN
MON EVEN
R S
POWER
SUPPLY
POWER
SUPPLY
+
-
+
+
-
-
*A V
CS+
CS-
*V CSTH
*ADJUSTABLE BY r47h [1:0]
R SENSE
TO ADC MUX
V MON
LOAD
OVERC
MAX16070