System Overview
7
SLVUBN3A – May 2019 – Revised October 2019
Copyright © 2019, Texas Instruments Incorporated
24-Port (4 Pair) Power Sourcing Equipment Reference Design for Multi-port
Applications
2.3.6
LM5017
The LM5017 device is used to generate 3.3 V to supply PSE devices.
The LM5017 is a 100-V, 600-mA synchronous step-down regulator with integrated high-side and low-side
MOSFETs. The constant on-time (COT) control scheme employed in the LM5017 device requires no loop
compensation, provides excellent transient response, and enables very high step-down ratios. The on-time
varies inversely with the input voltage resulting in nearly constant frequency over the input voltage range.
A high-voltage startup regulator provides bias power for internal operation of the IC and for integrated gate
drivers. A peak current limit circuit protects against overload conditions. The undervoltage lockout (UVLO)
circuit allows the input undervoltage threshold and hysteresis to be independently programmed. Other
protection features include thermal shutdown and bias supply undervoltage lockout (VCC UVLO).
2.3.7
LM5020
The LM5020 device is used to generate isolated LM5020 to supply MSP430 and isolators.
The LM5020 high-voltage pulse-width modulation (PWM) controller contains all of the features needed to
implement single-ended primary power converter topologies. Output voltage regulation is based on
current-mode control, which eases the design of loop compensation while providing inherent line feed-
forward. The LM5020 device includes a high-voltage start-up regulator that operates over a wide-input
range up to 100 V. The PWM controller is designed for high-speed capability including an oscillator
frequency range to 1 MHz and total propagation delays less than 100 ns. Additional features include an
error amplifier, precision reference, line undervoltage lockout, cycle-by-cycle current limit, slope
compensation, soft start, oscillator synchronization capability and thermal shutdown.
2.3.8
LM5050
The LM5050 device is used to support 2 power supplies in the system to work in backup mode.
The LM5050-1 and LM5050-1-Q1 high-side ORing FET controller operates in conjunction with an external
MOSFET as an ideal diode rectifier when connected in series with a power source. This ORing controller
allows MOSFETs to replace diode rectifiers in power distribution networks thus reducing both power loss
and voltage drops.
The LM5050-1 and LM5050-1-Q1 controllers provide charge pump MOSFET gate drive for an external N-
channel MOSFET and a fast response comparator to turn off the FET when current flows in the reverse
direction. The LM5050-1 and LM5050-1-Q1 devices can connect power supplies ranging from 5 V to 75 V
and can withstand transients up to 100 V.
2.3.9
INA240
The INA240 amplifier is used to measure the total current from the input to support fast shutdown in an
event of load step change.
The INA240 device is a voltage-output, current-sense amplifier with enhanced PWM rejection that can
sense drops across shunt resistors over a wide common-mode voltage range from –4 V to 80 V,
independent of the supply voltage. The negative common-mode voltage allows the device to operate
below ground, accommodating the flyback period of typical solenoid applications. Enhanced PWM
rejection provides high levels of suppression for large common-mode transients (
Δ
V/
Δ
t) in systems that
use PWM signals (such as motor drives and solenoid control systems). This feature allows for accurate
current measurements without large transients and associated recovery ripple on the output voltage. This
device operates from a single 2.7-V to 5.5-V power supply, drawing a maximum of 2.4 mA of supply
current. Four fixed gains are available: 20 V/V, 50 V/V, 100 V/V, and 200 V/V. The low offset of the zero-
drift architecture enables current sensing with maximum drops across the shunt as low as 10-mV full-
scale.