High-Side, Current-Sense Amplifiers with
12-Bit ADC and Op Amp/Comparator
MAX9611/MAX9612
12 _____________________________________________________________________________________
Detailed Description
The MAX9611/MAX9612 are high-side, current-sense
amplifiers with an integrated 12-bit ADC and an internal
selectable op amp/comparator. These devices are ideal
for a variety of industrial and automotive applications.
The MAX9611/MAX9612’s high-side, current-sense
amplifiers operate over a wide 0V to 60V input com-
mon-mode voltage range. The programmable full-scale
voltage (440mV, 110mV, and 55mV) allows for a wide
dynamic range current measurement and application
flexibility in choosing sense resistor values.
The I2C bus is 1.8V and 3.3V logic compatible and
can interface with modern microcontrollers. An internal
12-bit, 500sps integrating analog-to-digital converter
(ADC) allows the user to read analog signals such as die
temperature, VOUT, VSET, VRSCM, and VSENSE.
At power-up, the selectable op-amp/comparator block
is configured in the op-amp mode. The op amp has
an effective 60V Class A-type output stage and can be
used to limit inrush currents and create a current source
when used in a closed-loop system. When the internal
comparator is selected, the MAX9611/MAX9612 can
be configured to have a latched and retry functional-
ity, allowing a 60V open-drain transistor output, ideal to
operate high-side relay-disconnect FETs. The MAX9611
has a noninverting input-to-output configuration while the
MAX9612 has an inverting input-to-output configuration.
Current-Sense Amplifier
The MAX9611/MAX9612 feature a precision current-sense
amplifier with a 0V to 60V input common-mode voltage
range. An internal negative charge pump eliminates input
stage crossover distortion, typical in most rail-to-rail
input current-sense amplifiers. Low input bias currents
and low input offset currents allow a wide selection of
input filters to be designed without degrading the accu-
racy of the current-sense amplifier.
The current-sense amplifier inputs feature both a
-0.3V/+65V common-mode absolute maximum rating
as well as a Q65V differential absolute maximum rating,
allowing a wide variety of fault conditions to be withstood
easily by the device without damage.
The current-sense amplifier has a gain of 2.5V/V and
connects directly to the output op-amp/comparator
inputs. The ADC path features a 1x, 4x, and 8x program-
mable gain providing for 440mV, 110mV, and 55mV full-
scale sense voltage.
Analog-to-Digital Converter (ADC)
The MAX9611/MAX9612 feature an internal dual-slope
integrating 12-bit ADC that has a 2ms conversion time
and a 1.8V and 3.3V logic-compatible I2C bus. An inter-
nal mux allows the following on chip variables to be
read: input sense voltage, input common-mode voltage,
SET voltage, OUT voltage, and die temperature.
Temperature Measurement
Die temperature can be read by the ADC over the entire
operating range (-40NC to +125NC) with 0.5NC resolution.
Die temperature can be used for application calibration
and thermal monitoring and is available in a 9-bit, two’s
complement format. Readings outside of normal operat-
ing temperature range (-40NC to +125NC) are inaccurate
and should be considered invalid. See Table 1 for binary
and hex values.
Table 1. Binary and Hex Digital Output Values for Temperature Measurements
TEMPERATURE (NC) DIGITAL OUTPUT
BINARY HEX
+122.4 0111 1111 1xxx xxxx 7F8x
+24 0001 1001 0xxx xxxx 190x
+0.48 0000 0000 1xxx xxxx 008x
0 0000 0000 0xxx xxxx 000x
-0.48 1111 1111 1xxx xxxx FF8x
-24 1110 0111 0xxx xxxx E70x
-40 1101 1001 1xxx xxxx D98x