Detailed Description
The MAX9951/MAX9952 force or measure voltages in
the -2V to +7V through -7V to +13V ranges, dependent
upon the supply voltage range (V
CC
and V
EE
). These
devices also force or measure currents up to ±64mA,
with a lowest full-scale range of ±2µA. Use an external
buffer amplifier for current ranges greater than ±64mA.
MSR_ presents a voltage proportional to the measured
voltage or current. Place MSR_ in a low-leakage, high-
impedance state by forcing HI-Z_ low. Integrated com-
parators with externally programmable voltage
thresholds provide “too low” (DUTL_) and “too high”
(DUTH_) voltage-monitoring outputs. Each comparator
output features a selectable high-impedance state. The
devices feature separate FORCE_ and SENSE_ con-
nections and are fully protected against short circuits.
The FORCE_ output has two voltage clamps, negative
(CLLO_) and positive (CLHI_), to limit the voltage to
externally provided levels. Two control-voltage inputs,
selected independently of the PMU mode, allow for
greater flexibility.
Serial Interface
The MAX9951/MAX9952 use a standard 3-wire
SPI/QSPI™/MICROWIRE™-compatible serial port.
Once the input data register fills, the data becomes
available at DOUT. This data output allows for daisy-
chaining multiple devices. Figures 1, 2, and 3 show the
serial interface timing diagrams.
Serial Port Operation
The serial interface has two ranks (Figure 4). Each PMU
has an input register that loads from the serial port shift
register. Each PMU also has a PMU register that loads
from the input register. Data does not affect the PMU
until it reaches the PMU register. This register configura-
tion permits loading of the PMU data into the input regis-
ter at one time and then latching the input register data
into the PMU register later, at which time the PMU func-
tion changes accordingly. The register configuration also
provides the ability to change the state of the PMU asyn-
chronously, with respect to the loading of that PMU’s
data into the serial port. Thus, the PMU easily updates
simultaneously with other PMUs or other devices.
MAX9951/MAX9952
Dual Per-Pin Parametric
Measurement Units
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