Signal Consulting, LLC 

Model Si24SB4-50V-20A-AP1

Smart H-Bridge, with Aluminum Plate Heat-Sink, 5kHz or 20kHz PWM, Soft-Start and Soft-Stop, Active Low Control Inputs





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Si24SB4-50V-20A-AP1 Features:

Efficient H-Bridge: for Bidirectional Current Control
Directional Control: with External Forward, Reverse Keys
Max. Current for 5 sec : 40A with Proper Heat-Sink Installed
Max. Continuous Current: 20A with Proper Heat-Sink

Two User Selectable PWM Frequency: 5KHz or 20kHz

Two User Selectable Motor Acceleration/Deceleration Modes: Fast and Slow

Load-Current Indicator and Board Protection: An onboard bicolor LED is used to monitor the motor (or load) voltage (Red = Forward, Green = Reverse). The I1 analog control input is zener-diode protected and the board is protected by a fast-acting 20A Mini Fuse (DigiKey Part#: F993-ND).  

Adjustable Load Voltage (RPM): The average Load-Voltage (or motor RPM) is adjustable from 0V to 50V  (or max. value of Vp) in 0.83% steps with a Pulse-Width Modulation (PWM) control signal or with an internal/external potentiometer.

High Power-Efficiency: 98.5% typical, at 50V and 20A
Optically Isolated Directional Control Signals
Power Semiconductors: Four 60A Hex-MOSFETs
Overall Dimensions: 4.0" x 3.3" x 1.4" (10.2cm x 8.4cm x 3.4cm).
Components Type: 100% Solid State, NO Relays

On Board:
Filter Capacitors
VTS diodes
Snubber Circuit Ready
  Bicolor LED Indicator,  (red=forward,  green= reverse)

Voltage Requirement:
A single DC Source Voltage (unregulated and Unfiltered) with any voltage value from 9V to 50V (for Vp)

 For Details, Download the  Si24SB4-50V-20A-AP1-6Y1   Manual


The Si24SB4-50V-20A-AP1 is a 50V, 20A, microprocessor based, high-power, Smart H-Bridge with a small (4.0”x3.3”x0.062”) Aluminum Plate Heat Sink and with user selectable Soft-Start and Soft-Stop features. This controller uses a single (9V to 50V at 0 to 20A) DC power supply to control the speed of a DC motor (or load-current) in forward or reverse direction. An onboard microprocessor generates a 5kHz or 20kHz PWM carrier signal, controls the load-power (or motor speed), controls the load-current rate (or motor acceleration and deceleration). The PWM carrier frequency is user selectable by the jumper J2, 20kHz when J2 is open and 5kHz when J2 is short. This high frequency PWM rate insures a quiet motor environment. The user can choose between slow or fast (Soft Select) motor acceleration/deceleration modes using the jumper J3. The slow mode, with rise-time/fall-time of 1.25Sec, is selected by short-circuit (J3 jumper installed); while the fast buildup mode, with rise-time/fall-time of 0.05s, is selected by leaving the J3 pins open (no Jumper installed). As the name “Smart” implies the required motor speed (or PWM pulse-duration) is variable from 0 to 100% in 0.83% steps using the 0 to +5V analog voltage (VI1,G  on CN6), while the motor direction (or Load-Current Direction) is selected using two active low digital (0 to +5V) control signals (VF,N  and VR,N) or switches. A bicolor LED is used to monitor the motor (or load) voltage (Red = Forward, Green = Reverse). A small (4.0”x3.3”x0.065”) integrated Aluminum Plate Hear-Sink is used to operate at 20A current levels. Higher current-levels (25A or 750W) can be achieved with more efficient heat-sinks.

Please click on this link and read the Board Mounting Instructions and Heat Sink Selection Guide. This board operates in a wide voltage-range (9V to 50V) at max. continuous load-current of 20A. Typical applications are: Bi-directional DC Motor-Speed Controller, Peltier Effect TE Coolers, Heat Pumps, DPDT Solid State Relay, etc. This board can be configured and programmed to perform efficiently in many customized applications.

Motor Control-Action Truth Table, (Pins on Connector CN7)


 The motor action or load-current direction is controlled by active low control inputs, (0 to +5V) applied to Pin F (Forward) and/or pin R (Reverse) relative to Pin G (Ground) on the Connector CN7. These pins are optically isolated from the H-Bridge, providing good noise immunity for these inputs. The control actions and the required voltage levels are defined by the Truth-Table listed above. All control lines (analog and digital) are sampled approximately at 80Hz rate in the fast mode (J3 jumper open), and at 8Hz rate in the slow mode (J3 jumper short).

A Typical Application of the Si24SB4-50V-20A-AP1

 In this open-loop application, the PWM or motor speed (in forward or reverse direction) is adjusted by an external linear 1-turn 5kW potentiometer (Signal Part number Si5Pot1-5k ) connected to CN6. The motor direction is controlled by 2 external normally-open switches (Signal Part number Si24PB2-MC3 ) connected to port CN7, while the 2 optional normally-closed limit-switches are included here to prevent over-rotation in window-lifting applications (as shown below). Warning:  The connecting wires to the Load and the Power Supply must be heavy gauge copper wire (#12 AWG or heavier) to handle the rated current level. In addition, these heavy gauge wires act as a heat sink, protecting the board from overheating.

Si24SB4-50V-20A-AP1, Smart H-Bridge with Aluminum Plate Heat Sink 
Price $209.00

Note: If Buying the Si24SB4-50V-20A-AP1,  it is recommended to buy one Si5Pot1-5k Pot,  and a Si24PB2-MC3   Two Push-Buttons with 12" lead and with a 3-pin FM Molex Connector.

Si5Pot1-5k  One 1-Turn, 5kW Potentiometer with 12" leads.  
Price $15.00
Si24PB2-MC3   Two Push-Buttons with 12" lead and with a 3-pin FM Molex Connector.  
Price $29.00

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Availability: We usually ship in 2-3 business days.



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