Motech LPS-300 series

Motech LPS-300 series

Status	planned
Channels	1/3
Voltage/current (CH1)	0-30 V / 0-max. 3 A, model-dependant
Voltage/current (CH2)	0-30 V / 0-max. 3 A, model-dependant
Voltage/current (CH3)	3.3/5 V / 0-max. 3 A, model-dependant
Connectivity	RS232
Features	output on/off, calibration

The Motech LPS-300 series of programmable power supplies consists of 5 1-channel or 3-channel devices with optional RS232 connectivity.

The devices were also sold as the Amrel LPS-301 by American Reliance and partly under further brands.

Specifications

The models differ only in the number of available channels, maximum voltage and maximum current output:

Model	Power Output	Channels	Voltage/Current
LPS-301	30 W	1	30 V/1 A or 15 V/2 A
LPS-302	60 W	1	30 V/2 A or 15 V/4 A
LPS-303	90 W	1	30 V/3 A
LPS-304	70 W	3	±30 V/1 A or ±15 V/2 A; 5 V/2 A
LPS-305	165 W	3	±30 V/2.5 A; 3.3 or 5 V/3 A

The three-channel versions have the two main channels wired together for symmetric power supply, but the voltages can be set independantly, if desired. They can be set on or off only together.

These specifications are common to all models:

30 V Channels
	Voltage	Current
Programming Resolution	10 mV	1 mA
Programming Accuracy	0.05% + 20 mV	0.15% + 5 mA
Readback Accuracy	0.1% + 20 mV	0.2% + 5 mA
Ripple (10 Hz to 20 MHz)	1 mV rms / 10 mV p-p	10 mA rms
Load Regulation	0.001% + 1mV	0.01% + 1mA

These specifications apply only to models having a 3.3V/5V output:

3.3/5V Channel
	Voltage	Current
Ripple (10Hz to 20MHz)	2 mVrms / 10mVp-p	10mArms
Load Regulation	0.001% + 1mV	0.01% + 1mA

The devices can be calibrated easily requiring nothing but a multimeter of sufficient precision.

Protocol

The communication with the device is via an optional RS-232 port (Option 02). The port parameters are 2400 Baud, 8n1.

All commands are plain ASCII. All commands are terminated by \r, \n or \r\n. Another command sent before reception of the reply (usually OK) will be ignored. It seems that trailing digits for numerical parameters can be left away.

Commend	Reply	Description
BEEP(0|1|2|3)	OK	Beeper function 0: disable; 1: enable; 2: force alarm 3: off
CALI(0|1|2)	?	Calibration 0=end; 1=begin; 2=input parameter There seem to be no plausibility checks and the description is incomplete. Messing around with the calibration is strictly discouraged and can cause odd behaviour!
HELP	(see right) OK	Output list of commands (several lines)
IOUT(n)	d.dddd OK	Current readback
ISET(n) d.dddd	OK	Set output current
LOWA(0|1)	OK	CC output compensated 0=off; 1=on (what is this?)
MODEL	\r\nLPS-␣␣␣␣ OK	Get model number (reply seems to be incomplete, bug?)
OUT(0|1)	OK	Disable/enable output. OUT without a parameter seems to disable it.
STATUS	<decimal> OK	Working status, bitwise encoding. Bit 0, channel 1 mode: 0: CV 1: CC. Bit 1, channel 2 mode: 0: CV 1: CC. Bit 3,2, tracking: 00: independant; 10: to channel 1; 11: to channel 2. Bit 4, digital output 3: 0: off; 1: on. Bit 5, digital output voltage: 0: 5 V; 1: 3.3 V. Bit 6, output 1/2: off; 1: on. Bit 7, output 3: 0: ok; 1: overloaded. Bit 8, Fan: 0: off; 1: on Bit 9, beeper: 0: off; 1: enabled Bit 10, CC output compensated: 0: off; 1: on
TRACK(0|1|2)	OK	Tracking 0=independant; 1=from channel 1; 2=from channel 2. Tracking seems to mean that channels 1 and 2 are synchronous on multi-channel models.
VDD(0|3|5)	OK	Set ("digital") output 3 0=off; 1=3.3 V; 5=5 V
VERSION	\r\nVer-1.17␣\r\n OK	Get version number.
VOUT(1|2)	dd.ddd OK	Voltage readback
VSET(1|2) dd.ddd	OK	Set output voltage. Entering more than 3 post-dot digits will overwrite starting from the left! The specified resolution is 10 mV. However, the actual resolution seems to be slightly higher, possibly due to rounding during decimal to binary conversion or depending on calibration.
*	\r\nERROR\r\n OK	Error (invalid command).

OK means \r\nOK\r\n.

Resources

• LPS-301 - LPS-304 User Manual [1]
• LPS-305 User Manual [2][3]
• Datasheet [4]