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January 17, 2017

Constant current or constant voltage DC/DC converter module, up to 5Amps, up to 32V output for battery charging, supercapacitor charging, LED power, or laser diode control


Constant voltage-constant current module
This constant current module is useful for charging batteries or powering LEDs from a DC power source or any application which requires constant voltage or constant current. Other applications include filament power and electromagnet power,

Fault detection, current limit, short circuit protection, reverse polarity, low voltage input protection
Can be used as a simple CC/CV battery charger for lead acid or lithium batteries
Input voltage from 2 volts up to 36 volts (must be at least 0.5V higher than the output voltage required)
Can be used for high efficiency current control of LED and LED strings
User adjustable output voltage and current limit, down to 25mV output
Flexible voltage reducing DC/DC converter with current up to 5 amps
Huge compliance voltage swing, up to 32V, down to 25mV to maintain a constant current with a changing load resistance
Can be used to safely charge supercapacitors at high rates.
  Quantity 1-9 10-99 100-999 1000+
PST-DCCP constant current DC/DC step down converter add_to_cart.gif $24.95 $22.70 $19.90 $16.25
PST-DCCP-XX-YY factory adjusted,
specify maximum voltage and current settings required
add_to_cart.gif $29.95 $26.20 $22.90 $19.75
Optional barrel socket to screw terminal adapters
Price
ZHJX002
adapters with a barrel connector input and screw terminal output
5.5 x 2.1 mm barrel socket
$2.50 each
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5.5 x 2.1 mm barrel plug to screw terminal adapter
5.5 x 2.1 mm barrel plug
$2.50 each
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Optional DIN mounting hardware
DIN rail mount
(not including the rail)
$3.00
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PST-DCCP Specifications
Input voltage: 3V to 36V input
Output user adjustable: 0.025V to 36V output (input voltage must be at least 0.5V higher than output)
Peak output current: Up to 5 Amps, current limit is user-adjustable
Continuous output current 3.5 Amps
Isolation Non-isolated, common ground. To operate in constant current mode
both the positive and the negative output wires must be used
Adjustment method Pots accessible on the top of the unit.
The pot labeled W103 adjusts the output voltage limit.
The pot labeled W102 adjusts the output current limit.
Efficiency Up to 96% efficient with 5V or higher output, up to 87% with 3.3V output
Form Potted module with flying leads
Battery charging Works as a constant current - constant voltage battery charger. Will fold back the voltage to match the user adjustable maximum charge current, then when the voltage reaches the user adjusted maximum charge voltage it lets the current taper down. There is no LED indication when the battery is fully charged, but the battery can be left on the charge circuit indefinitely without being overcharged.
It is suitable for Lead Acid, Lithium Ion, Lithium Polymer, and Lithium Iron Phosphate batteries. See chart below.
Adjustment method Two multi-turn pots, these have many turns, so don't get discouraged, you can't damage the pots by turning them too far
LED Green = Input power on
Blue = Constant voltage mode
Red = Constant current mode
Note: the DC/DC converter will work with inputs down to 3V, but the LEDs
do not operate until the input raises to 5VDC.
Temperature range -10° to +60°C
Connections Wire leads 20AWG, 5 inches, 130mm long
Input: black and red
Output: black and yellow
Dimensions 2 x 4 x 0.78 inches, 52 x 103 x 20 mm including flange
Mounting holes 3.5 inches center to center, 0.185 inches diameter
88.5 mm center to center, 4.7mm diameter


labeled components of the constant-current DC/DC converter

User notes and applications.


NOTE: even though this is a common ground DC converter BOTH GROUNDS must be attached, one to the source negative and one to the load negative. It is OK if the source and load negatives are connected together.

Battery Charger

  1. First determine the highest voltage that the battery will float at
    1. For lead acid batteries the voltage will be 2.25-2.33 Volts/cell in series, or 13.4-14V for a 6-cell 12V Battery
    2. For lithium ion batteries the voltage is 4.2 Volts/cell in series
    3. For lithium iron phosphate batteries the voltage is 3.65 Volts/cell in series.
  2. Next set the maximum voltage on the PST-DCCP
    1. Attach a power source at lest 1 volt higher than the desired maximum charge voltage to the red and black leads
    2. Attach a volt meter to the output leads (yellow and black)
    3. Adjust the potentiometer labeled W103 to give the desired voltage
  3. Then set the maximum charge current desired
    1. You cannot adjust the output current while connected to the battery. Instead use the following protocol.
    2. Set your multimeter to the highest current setting, usually 10 or 20 Amps
    3. Attach the output leads of the PST-DCCP to the ammeter leads
      1. Note: this shorts the PST-DCCP, but it is OK, since the PST-DCCP can handle a short circuit. Don't try this with other power sources such as batteries, power supplies, and DC converters.
    4. Adjust the current setpoint potentiometer (labeled W102) to give the maximum current output that you require, less than 5 Amps
    5. Remove the ammeter
  4. Alternately you can select a resistor by the following equation R= Vmax/Imax
  5. Attach the output of the PST-DCCP to the resistor in series with the ammeter
  6. The resistor will get hot, so watch out
  7. Adjust the output current
Chemistry Number of cells in series Nominal pack voltage Maximum charge voltage
Lead Acid 1 2V 2.3V
  2 4V 4.6V
  3 6V 6.9V
  4 8V 9.2V
  5 10V 11.5V
  6 12V 13.8V
  7 14V 16.1V
  8 16V 18.4V
  9 18V 20.7V
  10 20V 23V
  11 22V 25.3V
  12 24V 27.6V
  13 26C 29.9V
Lithium Ion 1 3.6V or 3.7V 4.2V
  2 7.2V or etc. 8.4V
  3 10.8V 12.6V
  4 14.4V 16.8V
  5 18V 21V
  6 21.6V 25.2V
  7 25.2V 29.4V
LiFePO4 1 3.2V 3.65V
  2 6.4V 7.3V
  3 9.6V 11V
  4 12.8V 14.6V
  5 16V 18.3V
  6 19.2V 21.9V
  7 22.4V 25.6V
  8 25.6V 29.2V

Supercapacitor Charger

  1. Charging a supercapacitor through a standard resistance can take a long time due to the RC time constant. The constant current converter will raise the voltage continuously as the capacitor is filled, until the highest charge voltage is obtained without overshooting the maximum set voltage.
  1. First determine the highest voltage that the supercapacitor or ultracapacitor is rated for under continuous use.
    1. This is usually 1.25V to 4V per capacitor in series, depending on the manufacturer, check their data sheet
  2. Next set the maximum voltage on the PST-DCCP as follows:
    1. Attach a power source at lest 1 volt higher than the desired maximum charge voltage (red and black leads)
    2. Attach a volt meter to the output leads (yellow and black leads)
    3. Adjust the potentiometer labeled W103 to give the desired voltage
  3. Set the maximum charge current desired as follows
    1. Set your multimeter to the highest current setting, usually 10 or 20 Amps
    2. Attach the output leads of the PST-DCCP (black and yellow leads) to the ammeter
      1. Note: this shorts the PST-DCCP, but it is OK, since the PST-DCCP can handle a short circuit. Don't try this with other power sources such as batteries, power supplies, and DC converters.
    3. Adjust the current setpoint potentiometer (labeled W102) to give the maximum current output that you require, less than 5 Amps
    4. Remove the ammeter

LED controller

  1. Determine the highest voltage that the LED can accept
    1. This will be 1.6V to 32V depending on the color and the number of LEDS in series
    2. This is found on the LED data sheet
  2. Determine the electrical current that you want to operate at
    1. Some LEDs have current limiting resistors built-in. In this case the voltage is the critical parameter
    2. Other LEDS are current controlled. In this case current is the critical parameter.
    3. For high efficiency it is better to have the DC converter control the current, then no power is lost in the current limiting resistor
  1. Set the maximum voltage on the PST-DCCP
    1. Attach a power source at lest 1 volt higher than the desired maximum LED voltage (black and red leads)
    2. Attach a volt meter to the output leads
    3. Adjust the potentiometer labeled W103 to give the desired voltage
  2. Set the maximum charge current desired
    1. Set your multimeter to the highest current setting, usually 10 or 20 Amps
      1. If you want current lower than 500mA, use the high current setting first, then the mA setting for fine tuning
    2. Attach the output leads (black and yellow) of the PST-DCCP to the ammeter leads
      1. Note: this shorts the PST-DCCP, but it is OK, since the PST-DCCP can handle a short circuit. It will just reduce the voltage to stay within its output power parameters. Don't try this with other power sources such as batteries, power supplies, and DC converters.
    3. Adjust the current setpoint potentiometer labeled W102 to give the maximum current output that you require, less than 5 Amps
    4. Remove the ammeter

Laser diode controller

  1. Determine the highest voltage that the laser diode can accept
    1. This will be 1.2V to 5V depending on the wavelength of the laser
    2. This is found on the laser diode packaging or data sheet
  2. Determine the electrical current that you want to operate at
    1. Laser diodes are current controlled. In this case current is the critical parameter.
  1. Set the maximum voltage on the PST-DCCP
    1. Attach a power source at lest 1 volt higher than the desired maximum Laser diode (black and red leads)
    2. Attach a volt meter to the output leads
    3. Adjust the potentiometer labeled W103 to give the desired peak voltage
  2. Set the maximum charge current desired
    1. Set your multimeter to the highest current setting, usually 10 or 20 Amps
      1. If you want current lower than 500mA, use the high current setting first, then the mA setting for fine tuning
    2. Attach the output leads (black and yellow) of the PST-DCCP to the ammeter leads
      1. Note: this shorts the PST-DCCP, but it is OK, since the PST-DCCP can handle a short circuit. It will just reduce the voltage to stay within its output power parameters. Don't try this with other power sources such as batteries, power supplies, and DC converters.
    3. Adjust the current setpoint potentiometer labeled W102 to give the maximum current output that you require, less than 5 Amps
    4. Remove the ammeter
    5. It is a good idea to measure the current with the laser diode in place, in series with the ammeter to verify that the amperage is correct under the final load

DIN Rail Mount Option

din rail mount reverse view of DIN rail mounting
DIN rail mount Optional mounting hardware for 35mm or 15mm DIN rails. Rail not included.


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