Wavelength Electronics WHY5640, Datasheet And Operating Manual

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WHY5640 TEMPERATURE CONTROLLER
STEP 6 [OPTIONAL] Monitoring Setpoint & Actual
Sensor Voltages - Pins 1, 3, 5 - 7
Configure the WHY5640 to monitor the setpoint and actual
sensor voltages externally illustrated in Figure 10 .
Figure 10. Monitor Setpoint and Actual Sensor Voltages
Circuit
The WHY5640 internal sensor bridge amplifier becomes
balanced (or Pin 6 (ERR) equals 1 V) when the sensor
voltage equals the setpoint voltage in Figure 10 .
The circuit shown in Figure 10 uses a constant current
source to produce a sensing current through the resistive
temperature sensors resulting in a sensor voltage. A typical
sensing current for 20 kΩ and lower thermistors is 100 µA.
For thermistors higher than 20 kΩ use 10 µA. RTDs require
a sensing current of 1 mA.
NOTE: PTC (Positive Temperature Coefficient) sensors
such as RTD sensors, the AD590, and the LM335 require
that the output Pins 9 (OUTA - ) and 13 (OUTB +) be
reversed from the connection diagram on page 2
(Figure 2) to produce the proper cooling and heating
currents through the thermoelectric.
When using a 10K Thermistor, per Figure 10 , connect the
TEC as follows:
OUTPUT B+ → TEC +
OUTPUT A - → TEC -
OPERATION WITH RESISTIVE HEATERS
The WHY5640 can operate resistive heaters by disabling
the cooling output current. When using resistive heaters with
NTC thermistors, connect Pin 3 (LIMA) to Pin 1 (AGND) with
a 1.5 kΩ resistor.
Connect Pin 2 (LIMB) to Pin 1 (AGND) with a 1.5 kΩ resistor
when using RTDs, LM335 type and AD590 type temperature
sensors with a resistive heater.
Connect the resistive heater to Pins 9 and 13 to operate.
INCREASING OUTPUT CURRENT DRIVE
The WHY5640 is specifically designed to operate in a
master/booster output current boosting configuration. Two
or more WHY5640 controllers can be coupled to boost the
output current.
Figure 11 shows how to connect two WHY5640 controllers
together to increase the output current drive to 4.4 A.
Pin 4 (BUFA) and Pin 14 (BUFB) provide buffered outputs
of Pin 3 (LIMA) and Pin 2 (LIMB), respectively. The
booster controller is controlled by the master controller by
connecting Pin 4 (BUFA) of the master unit to Pin 3 (LIMA)
of the booster unit. Similarly, Pin 14 (BUFB) of the master
unit then connects to Pin 2 (LIMB) of the booster unit.
Each successive booster unit uses its buffered outputs,
Pins 4 and 14, to drive the next booster units output drive
section via its Pins 3 and 2. The master controller sets the
current limits for all successive booster controllers connected
to the master controller, requiring only one set of heat and
cool limit resistors.
Use Table 6 to determine the limit setting resistors, R
A
and
R
B
, based on the number of WHY5640 controllers paralleled
together.
+0.5V
SENSOR
BRIDGE
AMPLIFIER
1 7 6
10 k Ω
10 k Ω
10 k Ω 10 k Ω
10 k Ω
10 k Ω
SENSOR
VOLTAGE
MONITOR
SETPOINT
VOLTAGE
MONITOR
V
DD
VREF2
V
DD
R
T
or R
RTD
VREF1
VREF1
R
4
R
4 I
SENSE
=
LM324A
LM324D
LM324C
LM324B
THERMISTOR
OR
RTD
5
R
G
3
R
L
C
L
+1V
PROPORTIONAL/INTEGRAL
CONTROL LOOP
AGND SENS ERR PI LIMA
2N3906
2k Ω
5k Ω
2k Ω
SS
WHY5640