DC2706A - ANALOG DEVICES - Datasheet.Live

DEMO MANUAL DC2706A

Rev 0

DESCRIPTION

LTC4376

28V, 7A Ideal Diode and Switch

with Reverse Input Protection

Demonstration circuit 2706A showcases the LTC®4376

ideal diode controller with integrated MOSFET and –40V

reverse input protection. The board showcases the high

side switch functionality of the LTC4376 by utilizing an

additional switch MOSFET in conjunction with the GATE

pin of the device. The LTC4376 has a current capability All registered trademarks and trademarks are the property of their respective owners.

of7A. The board includes two independent LTC4376 ideal

diode circuits sharing a common ground and operating

over a range of 4V to 40V.

Design files for this circuit board are available.

Figure1. Basic Test Setup

DC2706 F01

–

28V

–

12V

LOAD

DEMO MANUAL DC2706A

Rev 0

QUICK START PROCEDURE

Overview

DC2706A features two independent LTC4376 ideal diode

circuits sharing a common ground. Each channel handles

up to 7A at room temperature with no air flow and can be

independently controlled, to turn ON or OFF, with the use

of the SHDN pin due to the series switch MOSFET. The

board is double-sided. Reference designators are dupli-

cated for the two sections of the board; the upper section

is suffixed A while the lower section is suffixed B.

Voltage and Current Capability

The voltage capability of DC2706A is clearly stated on the

top side silkscreen and on the schematic. The internal

MOSFET of the LTC4376 has a 40V BVDSS rating and

hence must be protected against unwanted voltage excur-

sions beyond that range.

The LTC4376 is designed to carry 7A provided that it is

enabled. When the part is disabled, the internal MOSFET is

turned off, however forward current can still flow through

the 0.7V body diode of the internal MOSFET. To allow full

ON/OFF control of current, the LTC4376 has a GATE pin

that can be used to control a series switch MOSFET. This

configuration is showcased on the DC2706A.

Shutdown

The LTC4376 may be shut down by moving the JP1

jumper to the OFF position, which pulls SHDN to VSS

through 100kΩ (RF). Shutdown reduces the quiescent

EXTERNAL CONNECTIONS

Signal connections are made via the row of turret posts

along the edges of the board.

GND (4 turrets, 4 Banana Jacks): These connections are

made directly to the ground planes.

VINA (1 Turret, 1 Banana Jack): Input voltage connection

for the LTC4376 circuit located on the upper section of

the board.

VINB (1 Turret, 1 Banana Jack): Input voltage connec-

tion for the LTC4376 circuit located on the lower section

of the board.

VOUTA (1 Turret, 1 Banana Jack) : Output voltage con-

nection for the LTC4376 circuit located on the upper sec-

tion of the board.

VOUTB (1 Turret, 1 Banana Jack) : Output voltage con-

nection for the LTC4376 circuit located on the lower sec-

tion of the board.

VSSA: Connection to chip ground for the LTC4376 circuit

located on the upper section of the board.

VSSB: Connection to chip ground for the LTC4376 circuit

located on the lower section of the board.

Jumper Settings

JP1A: Controls the SHDN pin state for the LTC4376 circuit

located on the upper section of the board. This jumper can

be set to OFF to pull down on the GATE pin of the LTC4376

(body diode will still conduct current to output), EXT to

make an external connection (by default the SHDN pin is

pulled high internally) and ON which pulls up the SHDN

pin to turn the LTC4376 on. As there is an external series

switch MOSFET present on the DC2706A, the SHDN pin

allows the LTC4376 to operate as a switchable diode.

JP1B: Controls the SHDN pin state for the LTC4376 circuit

located on the lower section of the board. This jumper can

be set to OFF to pull down on the GATE pin of the LTC4376

(body diode will still conduct current to output), EXT to

make an external connection (by default the SHDN pin is

pulled high internally) and ON which pulls up the SHDN

pin to turn the LTC4376 on. As there is an external series

switch MOSFET present on the DC2706A, the SHDN pin

allows the LTC4376 to operate as a switchable diode.

DEMO MANUAL DC2706A

Rev 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog

Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications

subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

QUICK START PROCEDURE

current to ≈9μA. In the ON position, the SHDN pin is

pulled up to VIN, enabling the LTC4376. In the EXT posi-

tion, the SHDN pin is connected through RF to the SHDN

turret. If the SHDN turret is left open, an internal 3μA pull

up asserts it high and the LTC4376 is enabled. To disable,

connect the SHDN turret to the neighboring VSS turret.

SHDN pin level shift circuits are shown in the data sheet.

Because the SHDN pin is high impedance, it is subject to

capacitive coupling. A 10nF noise bypass capacitor, CF,

works with RF to keep noise out of the SHDN pin. RF also

helps protect the SHDN pin against inadvertent overvolt-

age conditions that might arise from use of the SHDN

turret. It is important to note that if the switch MOSFET

(M1) is removed, then shutting down the LTC4376 does

not interrupt the forward current path. Even when the

LTC4376 is in the shutdown state, the internal MOSFET

body diode is still present and will conduct forward cur-

rent if no series switch MOSFET is present to block cur-

rent flow.

How to Operate DC2706A

A simple demonstration of DC2706A’s operation is as

follows (see Figure1). Connect two adjustable power sup

plies, each set to 12V. Connect one to VINA and nearby

GND, the second to VINB and its associated GND. Place

the SHDN jumpers in the ON position. Join the outputs of

VOUTA and VOUTB together at the input of a DC load of

up to 7A. Slowly adjust one power supply up and down

relative to the other while monitoring the power supply

currents. The higher supply will carry the load current,

with a narrow transition region where the voltages are

nearly identical and the supplies droop share. If one sup-

ply is shorted, the output voltage will not collapse—the

other supply will carry the load.

The switch functionality of the device can also be dem-

onstrated. Set VINA to 28V and VINB to 12V with both

JP1 jumpers set to the ON position. The LTC4376 will

operate as a diode and will allow conduction of the 28V

rail while blocking current flow to the 12V power supply.

Setting JP1A to OFF will turn off channel A and disconnect

the 28V from the output. As a result, the output will drop

down to the 12V VINB rail.

The internal MOSFET has a breakdown voltage of 40V.

This board is designed to operate at 28V. When perform-

ing input short tests at +24V, use the following circuit

(Figure2) to ensure that the internal MOSFET does not

break down. CSNUB, D6 and RSNUB serve to protect against

inductive transients that may exceed 40V breakdown of

the internal MOSFET.

Figure2. Protection Against Inductive Transients

CSNUB

3.3µF

COUT

2.2µF

100V

RSNUB

ESD1

VIN

4V TO 40V

VOUT

7A LOAD

INK

GATE

OUTK

VSS

SHDN

LTC4376

OUT

OPTIONAL

D3*

12V

*OPT FOR >24V INPUT SHORTS

SIMPLIFIED DIAGRAM

DC2706 F02

DEMO MANUAL DC2706A

Rev 0

 ANALOG DEVICES, INC. 2018

12/18

www.analog.com

ESD Caution

ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection

circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.

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