MAX1253 Datasheet, PDF (18/29 Pages) Maxim Integrated Products – Stand-Alone, 10-Channel, 12-Bit System Monitors with Internal Temperature Sensor and VDD Monitor

Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and V_DD Monitor
Write-Selected Channel Configuration
Registers (Command Code 1100)
The Write-Selected Channel Configuration Register com-
mand, 1100, writes to the three channel configuration
registers for the addressed channel (see Table 3). The
first register to be written is the upper threshold (2 bytes),
followed by the lower threshold (2 bytes), ending with the
channel configuration register (1 byte), all MSB first.
Writing to the configuration registers resets the alarm reg-
ister bits and the fault counters for the addressed chan-
nel. See the Channel Registers section for more details.
Write Global Configuration Registers
(Command Code 1101)
The Write Global Configuration Registers command,
1101, writes to three registers: the channel-enable reg-
ister (2 bytes), the input configuration register (2 bytes),
and the setup register (1 byte). The command address
bits are ignored. See the Global Configuration
Registers section for more details.
Global Configuration Registers
The global configuration registers consist of the chan-
nel-enable register, the input configuration register, and
the setup register. These registers hold configuration
data common to all channels.
Table 4. Channel-Enable Register Format
B11
(MSB)
TEMP
B10
VDD
B9
AIN0
B8
AIN1
B7
AIN2
B6
AIN3
Channel-Enable Register
The channel-enable register (Table 4) controls which
channels are converted while in automatic scan mode.
The register contents are ignored for manual conver-
sion commands. Each input channel has a correspond-
ing bit in the channel-enable register. A logic high
enables the corresponding analog input channel for
conversion, while a logic low disables it. In differential
configuration, the bits for odd channels are ignored. At
power-up and after a RESET command, the register
contents default to 111111111111b (all channels
enabled).
Input Configuration Register
The input configuration register (Table 5) stores the
configuration code for each channel as a 3-bit per
channel-pair code (see Table 6), selecting from five
input signal configurations: single-ended unipolar volt-
age, single-ended temperature, differential unipolar
voltage, differential bipolar voltage, and differential
temperature. Table 5 shows the input configuration reg-
ister format, and Table 6 shows the 3-bit encoding for
channel configuration. At power-up and after a RESET
command, the register contents defaults to
000000000000b (all inputs single ended).
B5
B4
B3
B2
B1
B0
(LSB)
AIN4
AIN5
AIN6
AIN7
Res
Res
Table 5. Input Configuration Register Format
B11
(MSB)
B10
B9
AIN0 and AIN1 configuration
B8
B7
B6
AIN2 and AIN3 configuration
B5
B4
B3
AIN4 and AIN5 configuration
B2
B1
B0
(LSB)
AIN6 and AIN7 configuration
Table 6. Channel Configuration Coding (3 Bits/Channel Pair)
CODE
000
001
010
011
100
101
110
111
AIN0, AIN2, AIN4, AIN6 CONFIGURATION
Single-ended input (power-up state)
Single-ended input
Single-ended, external temperature sensor input
Single-ended, external temperature sensor input
Differential unipolar encoded, positive input
Differential bipolar encoded, positive input
Differential external temperature sensor, positive input
Reserved
AIN1, AIN3, AIN5, AIN7 CONFIGURATION
Single-ended input (power-up state)
Single-ended, external temperature sensor input
Single-ended input
Single-ended, external temperature sensor input
Differential unipolar encoded, negative input
Differential bipolar encoded, negative input
Differential external temperature sensor, negative input
Reserved
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