System Overview
6
TIDA032 – October 2019
Copyright © 2019, Texas Instruments Incorporated
24-Port (2 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
lowpower 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 I
2
C bus and also
communicates to host CPU through I
2
C or UART to receive configurations and report system status.
2.3.3
ISO7741
The ISO7741 isolator is used to isolate I
2
C signals between PSE devices and the MCU.
The ISO774x devices are high-performance, quadchannel digital isolators with 5000 VRMS (DW package)
and 3000 VRMS (DBQ package) isolation ratings per UL 1577. This family of devices has reinforced
insulation ratings according to VDE, CSA, TUV and CQC. The ISO774x devices provide 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 double
capacitive 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 ISO7740 device has all four channels in the same direction, the ISO7741 device has
three forward and one reverse-direction channels, and the ISO7742 device has two forward and two
reverse-direction channels. If the input power or signal is lost, default output is high for devices without
suffix F and low for devices with suffix F.
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 VRMS (DW
package) and 3000 VRMS (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 has been 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.
