FEATURES
 Built-in Auto PID Control – the World’s First
 Maximum Output Voltage Swing: ±14.4V
 Maximum Output Current: 15A
 High Efficiency: > 92%
@VVPS = 18V & VTEC = 8V & ITEC = 15A
 High Temperature Stability: <±0.001°C
 Reduced Thermistor Injection Current: < 1μA
 Continuous Bi-directional Output
 Programmable Output Current and Voltage Limits
 TEC Temperature, Current and Voltage Signals
 Selectable Temperature Sensor Types: thermistor,
RTD, or temperature sensor IC
 High Reliability and Zero EMI
 Compact Size: 35.96 × 35.96 × 8.2 (mm)
 100 % lead (Pb)-free and RoHS compliant

APPLICATIONS
Driving high power TEC modules at high efficiency
without tuning the compensation network manually.

DESCRIPTION
TEC (Thermo-Electric Cooler) is a semiconductor
device which can cool down or heat up the
temperature of an object by injecting an electrical
current in one or the other direction. This TEC
controller, TEC18V15A, is designed to drive a TEC at
high efficiency for regulating the object temperature
precisely by controlling the direction and magnitude of
the current going through the TEC. It is powered by a
DC voltage between 5.5V to 18V and the output
current can go up to 15A without using a heat sink.
Figure 1 is photos of the actual controller
TEC18V15AD, one shows the signal pins, and the
other shows the power pins.
The controller TEC18V15A allows setting the set-point
temperature, maximum output voltage magnitude,
and the maximum output current magnitude
respectively. These three settings are the input
parameters for the three control loops: constant
temperature, constant current, and constant voltage.
Before hitting the maximum output voltage magnitude
or the maximum output current magnitude, the
temperature loop is in control. When hitting the
maximum output voltage magnitude, either outputting
a positive or negative value across the TEC, the
voltage loop takes over the control, the controller will
be outputting a constant voltage to the TEC; when
hitting the maximum output current magnitude, the
current loop takes over the control, the controller will
be outputting a constant output current to the TEC.
The highest output voltage magnitude is limited by the
maximum power supply voltage, and the maximum
output current magnitude is 15A.
The temperature signal can be obtained by using one
of these 3 temperature sensors: thermistor, RTD or
temperature sensor IC. When using a thermistor, the
set-point temperature range is determined by an
external temperature network formed by 3 resistors.
In order to reduce the injection current to the
thermistor to reduce the errors caused by the selfheating
effect, the injection current is provided in
pulse mode, reducing the current by 10 times as
opposed to a continuous current.
One advanced feature of this TEC controller is that it
comes with a smart auto PID control micro-processor
which senses and compensates for the thermal load
automatically at real time, without needing external
components to form a compensation network, nor
requiring to fine tune the network with load tediously.
The TEC controller with auto PID has a part number:
TEC18V15ADAPID for the DIP package &
TEC18V15ASAPID for the SMT package.
Conservative users can still choose using the
conventional analog compensation network. The same
as in the past, it requires a one-time pre-tuning the
network to match the thermal load, but provides
reliable and high accuracy control. For fixed thermal
load applications, conventional analog compensation
might be a good choice, while for applications with
variable or numerous types of thermal loads, the
automatic PID control is more suitable.
Figure 2 is the top view of the controller, showing the
pin names and the locations. There are a total of 32
pins in 2mm pitch. All the pins on the left are for
either control input or indication output signals; all the
right pins are power input or output.
The pin function details are given in Table 1.
At the thermistor input, there is a linearization circuit
for the thermistor, to make the temperature output
voltage be more linearly proportional to the actual
thermistor temperature. There is a voltage inverter
circuit, and it makes the temperature output voltage
be positively proportional to the temperature, since
the thermistor has a negative temperature coefficient.
These 2 circuits together are called temperature
measurement circuit. See Figure 6.
The set-point temperature voltage and the voltage
representing the actual temperature are sent to an
error amplifier. There is a compensation network
inserted in the loop, to stop the oscillation of the
controller caused by phase delay effects of the
thermal load. Therefore, the compensation network
must match the need for driving a particular thermal
load. To simplify the tuning, a tunable compensation
network is provided by the evaluation board for this
TEC controller. A detailed guidance about how to tune
the compensation network with a thermal load is given
in the evaluation board application note.