© 2022
8
WHY56ND TEMPERATURE CONTROLLER
The V
DD
power supply is used to power the WHY56ND
internal control electronics and must be capable of supplying
100 mA of current. The V
S
power supply is used to power
the WHY56ND output H‑Bridge and must be capable of
supplying a current greater than the LIMA and LIMB current
limit settings.
for Quick Connect Configuration Wiring.
A heatsink may be required to properly dissipate heat from
the WHY56ND mounting surface. Maximum internal power
dissipation is 9 Watts for the WHY56ND
.
OPERATION WITH THERMOELECTRICS
STEP 1
Limit Output Current - Pins 1- 3
Connect resistors or trimpots to Pins 1, 2, and 3 for fixed
heating and cooling current limits or independently adjustable
heating and cooling current limits.
shows the circuit
for correct connections.
Figure 4. Fixed Heat and Cool Current Limits
Refer to
to select appropriate resistor
values for R
A
and R
B
.
Figure 5. Resistor Value vs. Output Current
shows the relationship between current limit
resistor R
X
(either R
A
or R
B
) and maximum output current of
the controller.
shows these values.
1
2
3
AGND
WHY56ND
LIMA
LIMB
R
A
R
B
x
x
OPERATING INSTRUCTIONS —
STANDALONE
NECESSARY EQUIPMENT
The following equipment is required to configure the
WHY56ND for basic operation.
• WHY56ND Temperature Controller
• Thermistor or other temperature sensor
• Peltier‑type thermoelectric cooler or resistive heater
•
Optional: test load
•
Minimum 22 gauge wiring to TEC
•
Power Supply (see below)
•
Thermal solution kit: heatsink, thermal washer, and fan
SYSTEM DESIGN DECISIONS
Before the WHY56ND can be configured, several decisions
must be made:
•
What sensor is being used?
•
What is the operating maximum current and maximum
voltage?
•
Will the system, as designed, fit within the Safe
Operating Area (SOA)?
GROUNDING
Special attention to grounding will ensure safe operation.
Some manufacturers package devices with one lead of the
sensor or thermoelectric connected to the metal enclosure
or in the case of laser diodes, the laser anode or cathode.
POWER SUPPLY REQUIREMENTS
The recommended operating voltage is between
+5 to +26 VDC for V
DD
and +4.5 to +30 VDC for V
S
. The
voltage available to the thermoelectric or resistive heater is
the “Compliance Voltage.” Compliance voltage varies with
the input voltage. See Compliance Voltage section in the
Electrical Specifications on page 6.
Unless Earth and Instrument Ground are
connected via the power supply, Instrument Ground
is floating with respect to Earth Ground
Earth Ground on
USA 115 VAC wall socket
Common or
Instrument Ground
EARTH
DC POWER SUPPLY
-
+
