Evaluation Board User Guide
EVAL-LT4423-AZ
28V, 2A Ideal Diode & Switch Load
General Description
The EVAL-LT4423-AZ evaluation circuit showcases the LT4423, an ideal diode with integrated back to back Pchannel MOSFETs and a load switch designed to minimize power dissipation by regulating a 15mV forward voltage when enabled. Its fast OUT to IN reverse bias detection minimizes reverse current to prevent unwanted charging of the input source. The integrated thermal detection offers additional protection against over thermal conditions by disabling the power path.
The board features two independent LT4423 ideal diodes and load switches that share a common ground and operate over a 1.9V to 28V range.
Use the SHDN input to turn on and off power to the load. In shutdown mode, the LT4423 exhibits less than 500nA (typical) quiescent current to extend battery life. Design files for this circuit board are available.
Performance Summary (T A = 25°C)
| PARAMETER | SYMBOL | CONDITIONS | MIN TYP MAX | UNITS |
| Input Voltage | VIN | 2. | V | |
| Input to Output Voltage | I VIN – VOUT I | 30 | V | |
| Output Voltage | VOUT | -30 +30 | V | |
| Output Current | IOUT | VIN = 1.9V | 1. | A |
| VIN = 2V | 1. | A | ||
| 2.4V 5 VIN 5 28V | 2 | A |
Quick Start Procedure
The EVAL-LT4423-AZ evaluation circuit features two independent LT4423s that share a common ground. Each LT4423 is equipped with integrated P-channel MOSFETs in an ideal diode and switch load configuration. A diode-or arrangement is used to evaluate the LT4423’s performance. See Figure 1 and use the following procedure for proper measurement equipment setup:
- With the power off, set jumpers JP1 and JP2 to ON. Connect the input power supply to the board through the VIN and GND terminals of both channel A and B. Connect the load to the VOUTA and GND terminal. Tie VOUTB to VOUTA.
- Set the power supply of VINA = 12V, VINB = 5V, and turn ON.
- Observe VOUT = 12V.
- Slowly increase VINB’s voltage to 24V.
a. When VINB goes above 12V, observe VOUT rises with VINB.
b. When VINB = 24V, VOUT = 24V. - Slowly decrease VINB to 5V.
c. Observe VOUT follows VINB until VINB reaches 12V.
d. When VINB goes below 12V, VOUT = 12V - Set JP1 to OFF, observe VOUT = 5V.
- Set JP2 to OFF, observe VOUT = 0V.
ON/OFF Control
The LT4423 can be turned on and off by placing the SHDN jumper in the ON or OFF position. In the OFF position, the SHDN pin is connected to GND, disabling the power path. In shutdown, the quiescent current consumption of the LT4423 is reduced to ≈500nA (typical). In the ON position, SHDN is shorted to VIN to enable the LT4423 when the input voltage supply is within operational range.
In the EXT position, the SHDN pin is connected through a resistive divider from VIN or a voltage applied by an external source on the SHDN turret. By adding a resistive divider from VIN to GND, the EVAL-LT4423-AZ can be programmed to enabled/disabled at a specified VIN voltage.
Thermal Shutoff
In heavy load cases, the temperature of the LT4423 can reach over temperature conditions. The LT4423’s integrated thermal shutdown disables its power path when it exceeds 160˚C to protect the part. When the LT4423’s temperature lowers to 145°C, the thermal shutdown enables the power path again.
In cases where the load is heavy during startup, the LT4423 performs the thermal shutdown to rapidly disable and enable the power path until OUT follows IN.
STATUS Detection
STATUS is an open-drain output intended to indicate power-path conditions. STATUS is designed for connection to a power supply through pull-up resistors. The open-drain STATUS output pulls low when the LT4423 is in shutdown, reverse bias, or under thermal protection. Note that the STATUS function is optional and can easily be removed for simplicity by leaving STATUS open.
Performance Curves
(T A = 25°C, unless otherwise noted.)
Bill of Materials
| ITEM | I QTY | I DESIGNATOR | I DESCRIPTION | I MANUFACTURER PART NUMBER |
| REQUIRED CIRCUIT COMPONENTS | ||||
| 1 | 2 | C1, C2 | CAP CER 10uF 50V 10% X7R 1206 | SAMSUNG, CL31 B106KBHNNNE |
| 2 | 2 | C3, C4 | CAP CER 0.1uF 50V 10% X7R 0603 | AVX, 06035C104KAT2A |
| 3 | 2 | R1, R2 | RES SMD 100K Ohm 1% 1/10W 0402 AEC-Q200 100K R1 | PANASONIC, ERJ-2RKF1003X |
| 4 | 2 | U1, U2 | IC-ADI 28V, IDEAL DIODE AND LOAD | ANALOG DEVICES, LT4423AV#TRPBF |
| OPTIONAL CIRCUIT COMPONENTS | ||||
| 1 | 2 | D1, D2 | 10 SCHOTTKY 30V 1A 2LD SOD-523 | NEXPERIA, PMEG3010EB, 115 |
| 2 | 4 | D3-D6 | DIO TVS UNI-DIRECTIONAL 28V 600W DO-214AA | DIODES INCORPORATED, SMBJ28A-13-F |
| 3 | 4 | R3-R6 | DO NOT INSTALL (R0603) | TBD0603 |
| HARDWARE – FOR EVALUATION CIRCUIT ONLY | ||||
| 1 | 2 | SHUNT, 2POS, 2MM PITCH, BLACK | SAMTEC INC., 2SN-BK-G | |
| 2 | 4 | STANDOFF, BRD SPT SNAP FIT 15.9MM LENGTH | KEYSTONE, 8834 | |
| 3 | 2 | JP1, JP2 | CONN-PCB 6POS UNSHROUDED HEADER VERT 2MM PITCH | SAMTEC INC., TMM-103-02-L-D |
| 4 | 8 | TP1, TP2, TP7, TP8, TP11, TP12, TP17, TP18 | ONN-PCB, BANANA JACK, FEMALE, NON INSULATED, THT, SWAGE, 0.218 INCHES LENGTH | KEYSTONE ELECTRONICS, 575-4 |
| 5 | 12 | TP3-TP6, TP9, TP10, TP13- TP16, TP19 | CONN-PCB SOLDER TERMINAL TURRETS FOR CLIP LEADS | MILL-MAX, 2308-2-00-80-00-00-07-0 |
Schematic
Revision History
| REVISION NUMBER | REVISIONDATE | DESCRIPTION | PAGES CHANGED |
| 0 | 24-Sep | Initial release | — |
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Documents / Resources
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ANALOG DEVICES LT4423 Ideal Diode and Switch Load [pdf] User Guide LT4423 Ideal Diode and Switch Load, LT4423, Ideal Diode and Switch Load, Switch Load, Load |
