System Overview
6
SLVUBN3A – May 2019 – Revised October 2019
Copyright © 2019, Texas Instruments Incorporated
24-Port (4 Pair) Power Sourcing Equipment Reference Design for Multi-port
Applications
2.3.2
MSP430F523x
The TI MSP family of ultra-low-power microcontrollers consists of several devices featuring different sets
of peripherals targeted for various applications. The architecture, combined with extensive low-power
modes, is optimized to achieve extended battery life in portable measurement applications. The device
features a powerful 16-bit RISC CPU, 16-bit registers, and constant generators that contribute to
maximum code efficiency. The digitally controlled oscillator (DCO) allows the device to wake up from low-
power modes to active mode in 3.5 µs (typical). The MSP430F524x series are microcontroller
configurations with four 16-bit timers, a high-performance 10-bit ADC, two USCIs, a hardware multiplier,
DMA, a comparator, and an RTC module with alarm capabilities. The MSP430F523x series
microcontrollers include all of the peripherals of the MSP430F524x series except for the ADC.
MSP430F523x is the main controller to control PSE devices (TPS2388x) through the I2C bus and also
communicates to host CPU through I2C or UART to receive configurations and report system status.
2.3.3
ISO1541
The ISO1541 bidirectional isolator is used to isolate I2C signals between PSE devices and the MCU.
The ISO1540 and ISO1541 devices are low-power, bidirectional isolators that are compatible with I2C
interfaces. These devices have logic input and output buffers that are separated by TI's
Capacitive
Isolation
technology using a silicon dioxide (SiO2) barrier. When used with isolated power supplies, these
devices block high voltages, isolate grounds, and prevent noise currents from entering the local ground
and interfering with or damaging sensitive circuitry.
2.3.4
ISO7731
The ISO7731 digital isolator is used to isolate control signals (OSS, RESET, INT) between MSP430 and
PSE devices.
The ISO773x devices are high-performance, triple channel digital isolators with 5000 V
RMS
(DW package)
and 3000 V
RMS
(DBQ package) isolation ratings per UL 1577.
This family of devices has reinforced insulation ratings according to VDE, CSA, TUV, and CQC.
The ISO773x family of devices provides high electromagnetic immunity and low emissions at low power
consumption, while isolating CMOS or LVCMOS digital I/Os. Each isolation channel has a logic input and
output buffer separated by a silicon dioxide (SiO2) insulation barrier. This device comes with enable pins
which can be used to put the respective outputs in high impedance for multi-master driving applications
and to reduce power consumption. The ISO7730 device has all three channels in the same direction and
the ISO7731 device has two forward and one reverse-direction channel. If the input power or signal is lost,
the default output is high for devices without suffix F and low for devices with suffix F. See the device
Functional Modes
section for further details.
Used in conjunction with isolated power supplies, this device helps prevent noise currents on a data bus
or other circuits from entering the local ground and interfering with or damaging sensitive circuitry.
Through innovative chip design and layout techniques, electromagnetic compatibility of the ISO773x
device is significantly enhanced to ease system-level ESD, EFT, surge, and emissions compliance.
2.3.5
CSD19538
This 100-V, 49-m
Ω
, SON 3.3-mm × 3.3-mm NexFET™ power MOSFET is designed to minimize
conduction losses and reduce the board footprint in PoE applications.