FEATURES

 Built-in Auto PID Control – the World’s First

 Maximum Output Voltage Swing: ±24V

 Maximum Output Current: 15A

 High Efficiency: > 92%

@VVPS = 28V & VTEC = 14V & 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, TEC28V15A, 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 25V and the output

current can go up to 15A without using a heat sink.

Figure 1 is photos of the actual controller

TEC28V15AD, one shows the signal pins, and the

other shows the power pins.

The controller TEC28V15A 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:

TEC28V15ADAPID for the DIP package &

TEC28V15ASAPID 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.