Datasheet

LMP92001
SNAS507B –FEBRUARY 2011–REVISED APRIL 2012 www.ti.com
The analog control functionality is served by twelve 12-bit voltage output DACs. Besides producing voltage
corresponding to the digital input code, the DACs can be forced by the user to either rail instantaneously.
Additional digital monitoring and control can be realized via the General Purpose I/O port GPIO[7:0].
Two more blocks are present for added functionality: a local temperature sensor (already mentioned above) and
an internal reference voltage generator.
17-CHANNEL ANALOG SENSE WITH 12-BIT ADC
The user can monitor up to 16 external voltages with the 12-bit ADC and its 17-channel input MUX. Typically
these voltages will be generated by the analog sensors, instrumentation amplifiers, current sense amplifiers, or
simply resistive dividers if high potentials need to be measured. Channel 17 of the input MUX is reserved for the
internal temperature sensor, and is not available as an external input to the device.
User can program which MUX channels to enable, and whether to convert these channel inputs in sequence
continuously, or in a single-shot mode. Upon completion all conversion results are stored in the internal data
registers, and can be read back by the user via the I
2
C-compatible interface.
Analog input channels 1-3 and 9-11 have a built-in digital window comparator function with user programmable
thresholds. This function can be used to alert the supervisor microcontroller of an out-of-bound condition. The
comparator function result is stored in the internal status register which is user accessible. It can also be used as
the interrupt signal generator where the out of bound conditions will be reported via the INT[2:1] output pins.
Sequencing of the analog sense system is governed by the internal controller. Once enabled the MUX, the ADC,
the window comparator and the interrupts perform their function without further user intervention.
PROGRAMMABLE ANALOG CONTROL VOLTAGE OUTPUTS
Twelve identical individually programmable 12-bit DAC blocks are available to generate analog voltages, which
can be used to control bias conditions of external circuits, position of servos, etc.
In case simultaneous update of all outputs to the same level is needed, a single internal register is provided that
effects simultaneous update of all DAC data registers.
A DAC, by definition, produces an output in the range of GND to DREF. In some systems, however, it may be
desirable for the OUT pins to produce either GND or VDD, i.e., beyond DREF. This is made possible via the
asynchronous DAC control inputs C[4:1]. When activated, these inputs will force the OUT pins to either rail. The
choice of rail is made in the internal control register.
INTERNAL ANALOG TEMPERATURE SENSOR
An on-board analog temperature sensor is available to monitor the device’s own temperature. Once enabled, the
analog temperature sensor output is sampled via the MUX channel 17, and its conversion result is stored in the
internal register for user read back.
INTERNAL VOLTAGE REFERENCE SOURCE
Another resource available to the user is the internal, temperature-compensated reference voltage source. By
default both ADC and DACs expect reference potentials to be supplied externally. The user can choose to
enable the internal reference and use it with the ADC and/or the DACs.
The internal reference source cannot drive an external load.
8-BIT GENERAL PURPOSE I/O
The GPIO port can be used to expand the microcontroller capabilities. This port is memory mapped to the
internal register, which in turn is accessible via the I
2
C-compatible interface. Since each bit is individually
programmable as an Input or Output, the port is ideally suited for external switch control and status flag
monitoring, without further burdening of microcontroller I/O resources.
I
2
C-COMPATIBLE INTERFACE
The microcontroller supervisor communicates with LMP92001 via a popular I
2
C-compatible 2–wire interface. This
interface provides the user full access to all Data, Status and Control registers of the device.
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