Datasheet

Power-On Reset
The MAX11270 contains power-on reset (POR) supply
monitoring circuitry on both the digital supply (DVDD) and
the positive analog supply (AVDD). The POR circuitry
ensures proper device default conditions after either a
digital or analog power-sequencing event.
The digital POR trigger threshold is typically 1.2V with
respect to V
DGND
and has 100mV of hysteresis. The ana-
log POR trigger threshold is typically 1.25V with respect to
V
AVSS
and has 100mV of hysteresis. Both POR circuits
have lowpass filters that prevent high-frequency supply
glitches from triggering the POR.
Power-Down Modes
The MAX11270 can be powered down via the IMPD bit
in the command byte. The PD[1:0] bits of the CTRL1
register are used to select the power-down state. The SPI
remains fully functional in all power-down states.
Sleep Mode: The sleep mode can be set by writing 01 to
the PD[1:0] bits. In this state the internal subregulator that
powers the digital core is powered off. This is the lowest
power state for the device.
Standby Mode (10): The standby mode is set by writ-
ing 10 to the PD[1:0] bits. In this mode the device is not
active, but the internal subregulator is still powered on.
This allows conversions to start immediately after receiv-
ing a start conversion command.
Table 5. MAX11270 Command Behavior from Pin (RSTB, SYNC) and SPI (RESET, SYNC_SPI)
COMMAND
ISSUED
COMMAND-
ISSUED VIA
STATE
BEFORE
COMMAND
STATE
AFTER
COMMAND
TRANSITION
TIME (MAX)
COMMAND INTERPRETATION AND
RESULTING CHIP STATE
RESET
SPI or PIN
SPI, PIN
STBY STBY — Chip POR
SLEEP STBY 5ms Chip POR
Calibration STBY — Calibration stops, chip POR
Conversion STBY — Conversion stops, chip POR
IMPD
CTRL1:PD=’01’
SLEEP Mode
SPI
STBY SLEEP — Chip changes from STBY to SLEEP
SLEEP SLEEP — Chip remains in SLEEP
Calibration SLEEP — Calibrations stop
Conversion SLEEP — Conversion stop
IMPD
CTRL1:PD=’10’
STBY Mode
SPI
STBY STBY — Chip remains in standby
SLEEP STBY — Chip changes from SLEEP to standby
Calibration STBY — Calibrations stop, chip changes to standby
Conversion STBY — Conversions stop, chip changes to standby
MAX11270 24-Bit, 10mW, 130dB SNR, 64ksps Delta-Sigma
ADC with Integrated PGA
www.maximintegrated.com
Maxim Integrated │ 22