MAX1153/MAX1154
Stand-Alone, 10-Channel, 10-Bit System Monitors
with Internal Temperature Sensor and V
DD
Monitor
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• Manual conversion mode
• External reference for voltage measurements
Channel Enable Register Power-Up/Reset Defaults
At power-on or after a RESET command, the channel
enable register resets to FF hex, enabling all channels:
the internal temperature sensor, the V
DD
monitor, and
AIN0–AIN7.
Input Configuration Register
Power-Up/Reset Defaults
At power-on or after a RESET command, the input con-
figuration register resets to 00 hex, configuring
AIN0–AIN7 for single-ended voltage measurement.
Alarm Register Power-Up/Reset Defaults
At power-on or after a RESET command, the alarm reg-
ister is reset to 000000 hex, indicating that no alarm
condition exists.
Current Data Register Power-Up/Reset Defaults
At power-on or after a RESET command, each chan-
nel’s current data register is reset to 200 hex.
Upper Threshold Register Power-Up/Reset Defaults
At power-on or after a RESET command, each chan-
nel's upper threshold register is reset to 3FF hex. This
state effectively disables the upper threshold.
Lower Threshold Register Power-Up/Reset Defaults
At power-on or after a RESET command, each chan-
nel's lower threshold register is reset to 000 hex. This
state effectively disables the lower threshold.
Channel Configuration Register
Power-Up/Reset Defaults
At power-on or after a RESET command, each chan-
nel's configuration register is reset to 000 hex, which
configures the fault bits to cause an alarm to occur on
the first overrange or underrange condition and dis-
ables averaging.
Computing Data Throughput
The MAX1153/MAX1154 throughput rate depends on
the number of enabled channels, their configuration
(temperature or voltage), and the reference mode.
Voltage measurements require 10.6µs (typ) to com-
plete, and temperature measurements require 46µs.
Channel pairs configured for differential measurements
count as only one for throughput computation.
The reference system takes 20µs to power up in refer-
ence mode 00 prior to each temperature measurement,
40µs to power up in reference mode 01 after each sam-
ple wait period (if sample wait time > 80µs), and no
power-up time in reference mode 10.
The sampling period is calculated as follows:
t
sw
= (t
pu
) + (N
v
)t
conv[volt]
+ (N
t
)t
conv[temp]
+ t
wait
where:
t
sw
= all channels scan sampling period
t
pu
= reference power-up time
t
conv[volt]
= voltage-configured channel conversion time
N
v
= number of voltage-configured channels
t
conv[temp]
= temperature-configured channel conver-
sion time
N
t
= number of temperature-configured channels
t
wait
= sample wait time
The terms in the previous equation are determined as
shown by the number of enabled channels, the input
channel configuration (voltage vs. temperature), the
sample wait time, and the reference mode. The follow-
ing calculation shows a numeric example:
t
sw
= 40µs + 8 x 10.6µs + 2 x 46µs + 395µs = 611.8µs
• 40µs is the time required for the reference to power-
up (reference mode = 00) every time the
MAX1153/MAX1154 come out of automatic shut-
down mode after a sample wait period.
• 8 x 10.6µs is the time required for seven channels
configured for voltage measurement and the V
DD
monitor.
• 2 x 46µs is the time required for temperature mea-
surement (46µs for each temperature measurement
(internal or external)).
• 395µs is the sample wait time, set by bits B5, B6,
B7 of the setup register (see Tables 7 and 8).
The MAX1153/MAX1154 use an internal clock for all
conversions. The serial interface clock does not affect
conversion time.
Performing eight single-ended remote channels tem-
perature measurements, an internal temperature mea-
surement, and an internal V
DD
measurement with a
sample wait time of zero results in an average conver-
sion rate of 24ksps or 2.4ksps per channel.
Performing eight single-ended voltage measurements,
an internal temperature measurement, and an internal
V
DD
measurement with sample wait time of zero results
in an average conversion rate of 70ksps or 7ksps per
channel.
