ISL28025 Datasheet, PDF (21/47 Pages) Intersil Corporation – Precision Digital Power Monitor with Real Time Alerts

ISL28025
Functional Description
Overview
The ISL28025 is a digital current, voltage and power monitoring
device for high and low side power monitoring in positive and
negative voltage applications.
The digital power monitor (DPM) requires an external shunt
resistor to enable current measurements. The shunt resistor
translates the bus current to a voltage. The DPM measures the
voltage across the shunt resistors and reports the measured
value out digitally via an I²C interface. A register within the DPM
is reserved to store the value of the shunt resistor. The stored
current sense resistor value allows the DPM to output a current
value to an external digital device.
The ISL28025 can monitor the voltage, current and power of a
power supply rail. The ISL28025 has an additional low voltage
read to measure a voltage after the rail has been regulated. The
primary channel will allow and measure voltages from 0V to 60V
or from 0V to 16.384V, depending on the option of the ISL28025.
The auxiliary channel can tolerate and measure voltage from 0V
to VCC.
The ISL28025 has continuous fault detection for the primary
channel. The DPM can be configured to set an alert in the
instance of an overvoltage, undervoltage and/or overcurrent
event. The response time of the alert is 500ns from the event.
The ISL28025 has a temperature sensor with fault detection.
An 8-bit margin DAC, controllable through I²C communication, is
incorporated into the DPM. The voltage margining feature allows
for the adjustment of the regulated voltage to the load. The
margin DAC can help in proving the load robustness versus the
applied supply voltage.
The ISL28025 offers a 3.3V voltage regulator that can be used to
power the chip in addition to low power peripheral circuitry. The
DPM has an I²C power pin that allows the I²C master to set the
digital communication supply voltage to the chip. The operating
supply voltage for the DPM ranges from 3V to 5.5V. The device
will accept I²C supply voltages between 1.2V and 5.5V.
The ISL28025 accepts SMBus protocols up to 3.4MHz. The
device is PMBus compliant up to 400MHz. The device has packet
error code (PEC) functionality. The PEC protocol uses an 8-bit
cyclic redundance check (CRC-8) represented by the polynomial
x⁸+x²+x¹+1. The ISL28025 can be configured for up to 55
unique slave addresses using 3 address select bits. The large
amount of addressing allows 55 parts to communicate on a
single I²C bus. It also gives the designer the flexibility to select a
unique address when another slave address conflicts with the
DPM on the same I²C bus.
Functional Pin Descriptions
VBUS
VBUS is the power bus voltage input pin. The pin should be
connected to the desired power supply bus to be monitored. The
voltage range for the pin is from 0V to 60V or 0V to 16V
depending on the ISL28025 version.
VINP
VINP is the shunt voltage monitor positive input pin. The pin
connects to the most positive voltage of the current shunt
resistor. The voltage range for the pin is from 0V to 60V or 0V to
16V depending on the ISL28025 version. The maximum
measurable voltage differential between VINP and VINM is
80mV.
VINM
VINM is the shunt voltage monitor negative input pin. The pin
connects to the most negative voltage of the current shunt
resistor. The voltage range for the pin is from 0V to 60V or 0V to
16V depending on the ISL28025 version. The maximum
measurable voltage differential between VINP and VINM is
80mV.
AUXV
AUXV is the power bus voltage input pin. The pin should be
connected to the desired power supply bus to be monitored. The
voltage range for the pin is from 0V to VCC.
VCC
VCC is the positive supply voltage pin. VCC is an analog power
pin. VCC supplies power to the device. The allowable voltage
range is from 3V to 5.5V.
I2CVCC
I2CVCC is the positive supply voltage pin. I2CVCC is an analog
power pin. I2CVCC supplies power to the digital communication
circuitry, I²C, of the device. The allowable voltage range is from
1.2V to 5.5V.
GND
GND is the device ground pin. For single supply systems, the pin
connects to system ground. For dual supply systems, the pin
connects to the negative voltage supply in the system.
VREG_IN
VREG_IN is the voltage regulator input pin. The operable input
voltage range to the regulator is 4.5V to 60V.
VREG_OUT
VREG_OUT is the voltage regulator output pin. The regulated
output voltage of 3.3V is sourced from the VREG_OUT pin.
ADDRESS PINS (A0, A1, A2)
A0, A1 and A2 are address selectable pins. The address pins are
I²C/SMBus slave address select pins that are multilogic
programmable for a total of 55 different address combinations.
There are four selectable levels for the address pins, I2CVCC,
GND, SCL/SMBCLK and SDA/SMBDAT. See Table 45 for more
details in setting the slave address of the device.
SMBDAT
SDA/SMBDAT is the serial data input/output pin. SDA/SMBDAT
is a bidirectional pin used to transfer data to and from the device.
The pin is an open-drain output and may be wired with other
open-drain/collector outputs. The input buffer is always active
(not gated). The open-drain output requires a pull-up resistor for
proper functionality. The pull-up resistor should be connected to
I2CVCC of the device.
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FN8388.3
June 17, 2015