Solenoid, Relay, Valve Driver with Current Regulation

Rajkumar Sharma
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SKU: EL141008
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The project presented here is a PWM current driver for solenoids, Relays, and valves. The board will regulate the current with a well-controlled waveform to activate and reduce power dissipation at the same time. The solenoid current is ramped up fast to ensure the opening of the valve or relay. After the initial ramping, the solenoid current is kept at peak value to ensure the correct operation, after which it is reduced to a lower hold level in order to avoid thermal problems and reduce power dissipation.

The peak current duration is set at 78ms with an external capacitor C2. The current ramp peak level can be adjusted using the PR1 trimmer potentiometer in the range 83mA to 250mA, the default PWM frequency is 20KHz, PWM frequency can be changed between 20Khz to 60Khz using the external resistor R4. The enable pin has an internal pull-up, so normally chip is enabled, pulling down the enable pin brings the chip into disable mode.

Features

Power Supply 6V to 24V DC
Load Current up to 250mA
Peak Current Duration 78mS
Peak Current Adjustable range 83mA to 250mA
Start-Up Delay Approx 25uS
PWM Frequency 20Khz
On Board Switch to disable the output
Enable Pin for External Connector
Header Connector for Power and Solenoid
Fast Ramp-Up of Solenoid Current to Guarantee Activation
Integrated Sense Resistor for Regulating Solenoid Current
Solenoid Current is Reduced in Hold Mode for Lower Power and Thermal Dissipation
Internal Supply Voltage Regulation
Thermal Shutdown, Threshold 160 Degree Centigrade
Undervoltage Lockout (UVLO), Threshold 4.6V
Compact Design
PCB Dimensions 22.23 x 17.78mm

Connections and Other Details

CN1: Pin 1 Enable (High = Enable, Low = Disable) High = 4V to 7V, Pin 2 = GND
CN2: Pin 1 VCC 6V to 24V DC, Pin 2 = GND
SL1: Pin 1 = Solenoid, Pin 2 VCC (Connections for Solenoid)
D2: Power LED
SW1: Disable Switch Push to Disable

Schematic

Parts List

NO.	QNTY.	DESC.	REF.	MANUFACTURER	SUPPLIER	SUPPLIER PART NO
1	2	CN1,CN2	2 PIN MALE HEADER PITCH 2.54MM	WURTH	DIGIKEY	732-5315-ND
2	1	C1	100nF/50V CERAMIC SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
3	1	C2	1uF/35V CERAMIC SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
4	1	C3	10uF/35V CERAMIC SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
5	1	D1	1N4007 SMD DIODE	DIODE INC	DIGIKEY	S1MBDITR-ND
6	1	D2	LED RED SMD SIZE 0805	OSRAM	DIGIKEY	475-1278-1-ND
7	1	PR1	1M TRIMMER POTENTIOMETER	BOURNS	DIGIKEY	3362P-105LF-ND
8	1	R1	DNP
9	1	R2	1K 5% SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
10	1	R3	3.3K 5% SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
11	1	R4	200K 1% SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
12	1	SL1	2 PIN MALE HEADER PITCH 2.54MM	WURTH	DIGIKEY	732-5315-ND
13	1	SW1	TACTILE SWITCH	C&K	DIGIKEY	CKN9085CT-ND
14	1	U1	DRV120	TI	DIGIKEY	296-34777-1-ND