CENTENT CN0121A User manual

CN0121A
H-BRIDGE AMPLIFIER
3879 SOUTH MAIN STREET 714-979-6491
SANTAANA, CALIFORNIA 92707-5710 U.S.A.
0 M P A N Y

This manual contains information for installing and operating the following
Centent Company product:
CN0121A H-Bridge Amplifier
Centent and the Centent Company logo are trademarks of Centent
Company. Other trademarks, tradenames, and service marks owned or
registered by any other company and used in this manual are the
property of their respective companies.
Copyright ©2017 Centent Company
3879 South Main Street
Santa Ana, CA 97207
All Rights Reserved

GENERAL DESCRIPTION
The CN0121A is an H-Bridge Servo Amplifier designed for bi-directional operation of
permanent magnet (PM) DC motors. The control features a conservative design employing
rugged 15 amp, 80 volt output transistors. It is a linear, Class B, current limited amplifier.
When adequately heat sunk it can dissipate up to 150 watts of power. There are no safe
operating area (SOA) load restrictions, so full output current is available at any voltage. The
CN0121A also features a precision two-quadrant current sense amplifier for feedback
applications. If the CN0121A is configured as a motor speed control, the Speed Regulation
Trimpot is used to adjust for motor speed regulation. Convenient external phase
compensation is provided, making this amplifier ideal for use in position or velocity servo
applications.
2
13
(1) TERMINAL STRIP CONNECTOR
No terminals or connectors are required on the wiring to the CN0121A. The recommended
wire size is 16-22 gauge. The terminal assignments and functions are described in the
following sections.
MOTOR OUTPUTS TERMINALS 1 & 9
The positive motor lead is connected to Terminal 1 and the negative motor lead is connected
to Terminal 9. With the motor connected in this way, when the voltage on the non-inverting
input, Terminal 7, is greater than the voltage on the inverting input, Terminal 8, the motor
will turn clockwise. When the voltage on Terminal 7 is less than the voltage on Terminal 8
the motor will turn counter-clockwise.
The output voltage across the motor is ± 25 volts with a 28 volt power supply. The maximum
motor current is 5 amps. The motor output terminals are diode clamped to ground and to the
positive supply voltage. The CN0121A's output stages are conservatively designed, utilizing
15 amp @ 80 volt power transistors.
1

CURRENT LIMIT OUTPUTS TERMINAL 3 & 4
A resistor is connected between these Terminals to set the motor output current limit. If no
resistor is used the motor current limit is 5 amps. The resistor value is calculated from the
following equation:
LIM
LIM
III
R− =5)600( Where: ILIM = output current and RI= limit resistor
Resistance values for output currents ranging from 1 to 5 amps in ½ amp increments are
printed on the CN0121A for user convenience. The following table also lists the closest
values for the given motor current using standard ¼ Watt, 5% Carbon Film Resistors.
CURRENT LIMIT TABLE (Terminals 3-4)
AMPS RESISTANCE 5% RESISTOR
5.0 OPEN none
4.5 5400 ohm 5.6K
4.0 2400 ohm 2.4K
3.5 1400 ohm 1.5K
3.0 900 ohm 910
2.5 600 ohm 620
2.0 400 ohm 430
1.5 257 ohm 270
1.0 150 ohm 150
DIFFERENTIAL INPUTS TERMINALS 7 & 8
Terminal 8 is the inverting input and Terminal 7 is the non-inverting input. If the voltage on
Terminal 7 is positive with respect to Terminal 8 the motor will turn clockwise. If Terminal 7
voltage is less than Terminal 8 voltage, the motor will turn counter-clockwise.
The input impedance is 10K ohms. The Common-Mode Voltage range is from the positive
supply voltage to -1 volts. The maximum Input Offset Voltage is 20 millivolts. The
Differential Voltage Gain is internally set to 27. With a 28 volt power supply, a voltage of ±1
volt between the inputs is sufficient to drive the output to saturation in either direction.
the
CN0121A.
NON-INVERTING INPUT
INVERTING INPUT
SUPPLY GROUND
7
8
SPEED
POT
10K
10
The motor may be driven by
connecting a 10K ohm
potentiometer across the inverting
and non-inverting inputs with the
wiper connected to ground. This is
shown on the cover of
2

CURRENT SENSE OUTPUT TERMINAL 5
This output provides a voltage proportional to the motor current. It is offset from ground
potential by one half of the power supply voltage. The output impedance is 10K ohms.
A clockwise turning motor's current causes the Current Sense Output voltage to become
more positive. A counter-clockwise turning motor's current causes the output voltage to
become more negative.
The transconductance of this stage is variable. It ranges from 0 to 15 volts per amp of motor
current and is adjusted by the Speed Gain Trimpot.
SUMMING NODE TERMINAL 6
This node sums the differential amplifier output, the Current Limit Output, and if connected,
the Current Sense Output.
Connecting the Current Sense Output, Terminal 5, to the Summing Node will make the
CN0121A operate as a speed control.
.
5
If a Phase Compensation Network is
necessary, it may be connected to the
Summing Node, Terminal 6
CURRENT SENSE
6
SUMMING NODE
POWER SUPPLY INPUTS TERMINALS 2 & 10
The power supply is connected to Terminal 2 and Terminal 10. Terminal 2 is the positive
supply input and Terminal 10 is the supply ground.
Reversing the power supply leads to the CN0121A will result in destruction of the drive;
so be careful to check the wiring before powering up the drive.
A regulated supply is recommended but is not necessary. The power supply voltage can
range from 9 VDC to 32 VDC. Do not exceed the CN0121A's maximum rated voltage. The
current rating of the power supply must be at least equal to the maximum motor current plus
the quiescent current draw for the CN0121A. Quiescent current draw (motor not connected)
is 22 milliamps @ 9 VDC to 75 milliamps @ 32 VDC.
(2) SPEED GAIN TRIMPOT
3
This multi-turn trimmer potentiometer is located on the front face of the CN0121A adjacent
to the Input/Output Connector. Adjusting the Speed Gain Trimpot will offset the motor's
series resistance; thus making motor speed
independent of the torque load. Turn the
trimmer clockwise to increase gain and thus
maintain speed under load. Turn the trimmer
counter-clockwise to decrease gain.
CW INCRESASES GAIN
12

The following procedure should be used to adjust the Speed Gain Trimpot:
4
1) Set the motor speed to 5-10% of maximum speed.
2) Apply a load to the motor and observe if the speed
increases or decreases.
3) Remove the load.
4) If speed increases under load, turn the trimpot counter-
clockwise.
If speed decreases under load, turn the trimpot
clockwise.
5) Repeat steps 2 through 4 until there is no observable
change in speed when load is applied or removed.
Note: if the motor oscillates when step 1 is attempted, turn the
trimpot counter-clockwise until the motor runs smoothly;
then proceed with steps 2-5.
(3) MOUNTING PLATE
The CN0121A is a linear amplifier. As a consequence it may dissipate considerable heat
while running large motors at low speed under heavy load. This heat may cause damaging
temperatures in the CN0121A. For this reason it is extremely important to properly heat sink
the drive.
Mount the CN0121A on a finned aluminum heat sink using thermal compound between the
CN0121A and the heat sink. If needed, use a fan to force air over the heat sink. Monitor the
case temperature of the CN0121A under the worst case motor load conditions. Do not let the
case temperature exceed 70°C (158°F).

INVERTING INPUT
+9 TO 32 VOLT DC
2.625"
66.7mm
3.25"
82.6mm
3.0"
76.2mm
3.650"
92.7mm
4.0"
101.6mm
0.85"
21.6mm
0.125"
3.2mm
0.186”
4.7mm
0.20"
5.1mm
SPEED GAIN
MOTOR OUTPUT (+)
CURRENT LIMIT
CURRENT LIMIT
CURRENT SENSE
SUMMING NODE
NON-INVERTING INPUT
MOTOR OUTPUT (-)
SUPPLY GROUND
11098765432
M
O
T
O
R
CENTENT CN0121A
H-BRIDGE AMPLIFIER
POWER
SUPPLY
R 1
see table
10K
SPEED
POT
CW increases gain
CURRENT LIMIT
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
open
5400 ohm
2400 ohm
1400 ohm
900 ohm
600 ohm
400 ohm
257 ohm
150 ohm
AMPS RESISTOR
SPECIFICATIONS
ELECTRICAL MIN. MAX. UNIT
Power Supply Voltage 9 32 VDC
Power Supply Current * -- 70 mA
Motor Voltage * -25 +25 VDC
Maximum Load Current -5 +5 A
Voltage Gain 25.6 28.3 %
Frequency Response DC 20 KHz
Common Mode Range -1 Vsupply V
Input Impedance -- 10K ohms
Input Offset -- 20 mV
Input Bias Current (inputs grounded) -- 150 µA
Current Range Limit -5 +5 A
Current Sense Output 0 15 V/A
* using 28 VDC power supply
ENVIRONMENTAL MIN. MAX. UNIT
Operating Temperature -40 +70 ºC
Weight 300 400 gram
Terminal Screw Torque 4.5 lb/in
5