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400 Hot Springs Road, Carson City NV 89706 • (775) 883-0820 • Fax (775) 883-0827 • www.hytek.com • 1
HY5630
TEC Controller
TEC Controllers Laser Diode Drivers Micro-heaters
Subminiature Controller for Thermoelectric Coolers
The HY5630 is a subminiature proportional temperature
controller for thermoelectric coolers (TEC). This device is intended for “cool only” fixed temperature applications where front
panel controls and digital readouts are not required. The
HY5630 operates in conjunction with a thermistor bridge to precisely measure and regulate the temperature of a device affixed
to a TEC while displaying stabilization condition via an external
LED. With proper heat sinking, the power stage of this device
will deliver up to 2 Amperes of current to a TEC and will operate
from a 5 to 12 volt power supply.
Features:
✦ Proportional/Integral (PI) control
✦ Small size
✦ Drive current to 2 amps
✦ Operation to 12 volts
✦ Control –55°C to ambient
✦ Integrated Window Comparator
✦ T emperature Stability to 0.01°C
✦ Thru-hole or surface-mount packaging
The HY5630 TEC controller consists of a thermistor bridge
amplifier, a window comparator , an integrator/gain stage
and a voltage-to-current converter power drive stage. This is
illustrated in the simplified schematic diagram for the
HY5630 in Figure 1. The thermistor bridge precisely measures the temperature of a device attached to a Thermoelectric Cooler (TEC). The bridge is balanced when the
thermistor value is equal to the value of the temperature set
resistor (Rs). When power is first applied to the TEC, the
temperature of the device attached to the TEC is higher
than the desired set temperature. The resistance of the
thermistor is therefore less than the temperature set resis-
Maximum Ratings:
Rating Symbol Value Unit
Supply Voltage VDD +20 Volts DC
Supply Voltage 2 (Voltage on Pin 12) VS +12 Volts DC
Current Sink IS 2.5 Amperes
Maximum Power Dissipation PMAX 6 Watts
Operating Temperature (Case) TMAX/MIN 100/–20 °C
Storage Temperature TSTG –65 to +150 °C
tor. This causes the current sink to turn on to its
maximum programmed value. This maximum current
is set with resistor Rc. The HY5630 will continue to
sink maximum current until the programmed temperature is reached. The current will then decrease to the
value required for maintaining equality between the
thermistor and the programming resistor (Rs). A window comparator measures the output of the thermistor bridge and can illuminate an external LED
when the thermistor is within ±2.4°C of setpoint. This
window can be narrowed with an external resistor
(Rw).
Figure 1
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2 • 400 Hot Springs Road, Carson City NV 89706 • (775) 883-0820 • Fax (775) 883-0827 • www.hytek.com
HY5630
TEC Controller
Description of the HY5630 Pin Outs
• Temperature Set Resistor RS (Pin 1 to Pin 5)
The temperature set resistor for the HY5630 controls the
temperature at which the TEC will operate. When the circuit has stabilized, the resistance of the thermistor will
be equal to that of the set resistor Rs. For example, if a
Dale 10KW thermistor is used as the temperature sensing device, a set resistor of approximately 56KΩ will set
an operating temperature of
–10°C. A graph of Rs vs. set temperature is shown in
Figure 4 when using a Dale 1M1002 thermistor.
• Thermistor, RT (Pin 5 to Pin 6)
The thermistor should be located in close proximity to
the device being cooled. It should be in good thermal
contact with this device to avoid stability problems.
The HY5630 has been designed for a negative temperature coefficient thermistor (5k to 20k nominal). A
thermistor with a positive temperature coefficient can
also be used if the position of the temperature set resistor and temperature sensing resistor are changed. The
same result can also be achieved by reversing the leads
of the TEC.
• Stabilization Window Set Resistor, R
W
(Pin 7 to Pin 8)
A circuit internal to the HY5630 measures the output of
the Thermistor Bridge. A switch closure to power ground
occurs when the output of this bridge is between 2.4 and
2.6V . This indicates that the temperature of the detector
has stabilized to within 2°C of the programmed set temperature. This switching occurs between Pin 1 1 and
power ground Pin 14 and can sink up to 200 mA of external LED current. A 2000 ohm potentiometer can be connected between pins 7 and 8 to increase the sensitivity
of the T emperature Stabilization Indicator . This will narrow
the temperature range at which switching occurs with coincident LED illumination.
• Loop Stability network, RL and CL
(Pin 4 to pin 2)
The RC time constant of these two components is a
first approximation of the thermal time constant of the
servo loop. The thermal time constant of the combination
of the device being cooled, the thermistor, and the TEC
can be approximated by applying constant power to the
TEC and measuring the length of time it takes to reach
66% of its final temperature.
For example, if the thermal time constant was observed to be 5 seconds, then a 1µF capacitor and a
4.7MΩ could be chosen as the loop stabilizing components. Typical values for loop compensation components
are shown in T able 1.
Note: The values of R
G, RL and CL are generally selected
by experiment. CL should be a low leakage
nonpolarized capacitor.
• Current Limit Resistor, RC (Pin 1 to Pin 2)
This resistor limits the maximum current that the
HY5630 can sink. This feature will prevent damage to the
TEC during turn-on. If the supply voltage for the TEC
does not exceed the maximum TEC voltage, then this resistor may not be needed. Figure 5 shows the approximate values for Rc required to program a desired turn-on
current.
• VDD (pin 9 to Pin 14) +7
≤≤
≤≤
≤
VDD
≤≤
≤≤
≤
+20 Volts
This input supplies the voltage to the internal circuitry of
the HY5630. The maximum current drain at this terminal
is 5mA.
• Thermoelectric Controller, TEC (Pin 12)
+3
≤≤
≤≤
≤
Vs
≤ ≤
≤ ≤
≤
+12 Volts
Pin 12 connects the TEC to the programmable current
sink in the HY5630. The other lead of the TEC is connected to + VS. At turn-on, the current into Pin 12 is
maximum if the temperature of the sensing thermistor is
greater than the programmed set temperature. This maximum turn-on current can be limited by RC. Once the TEC
reaches its set temperature, the current through the TEC
will drop to exactly the value required to maintain the correct set temperature.
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400 Hot Springs Road, Carson City NV 89706 • (775) 883-0820 • Fax (775) 883-0827 • www.hytek.com • 3
HY5630
TEC Controller
Figure 2 illustrates the characteristics of the
HY5630 current sink. It also illustrates the
unsafe operating area where the power
dissipated in the device exceeds the maximum
6 watt rating for this device.
Note that the resistance of the current switch is
approximately one ohm when the current switch
is saturated.
Figure 3 illustrates the locus of operating
current and voltage for two different TECs.
Example 1:
A supply voltage of 5 Volts was chosen for use
with the ITI Ferro T ek Model 6300/018/018A
TEC. This device is rated for a maximum current
of 1.8 Amperes at a maximum allowable voltage
of 2.7 Volts. This is a load resistance of
approximately 1.5 ohms. The intersection of the
1.5 ohm load line and the HY5630 current
source characteristics define the locus of
operation voltage and current for both the
HY5630 and the TEC. In this application the
current was limited to 1.8 Amperes by proper
selection of RC.
Example 2:
A supply voltage of 12 Volts was chosen for the
Melcor FC 0.45-66-05 TEC. This device has a
maximum rated voltage of 7.98 Volts at a
current of 0.8 Amperes. A load line for this
device is also shown on the plot.
Note that the power dissipated in the HY5630
never exceeds the 6 Watt maximum power
dissipation.
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4 • 400 Hot Springs Road, Carson City NV 89706 • (775) 883-0820 • Fax (775) 883-0827 • www.hytek.com
HY5630
TEC Controller
Figure 4
Figure 7
Figure 5
Figure 6
NOTES:
1. Make certain the heat sink to
which the HY5630 is mounted is
flat and clean, otherwise the
ceramic substrate may break.
2. Use a thermal compound such
as Dow Corning 340 between the
HY5630 and the heat sink for
good thermal conduction.
Specifications subject to change
without notice.
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