hytek HY-5610 TEC CONTROLLER Microsystems 11/97 SUBMINIATURE CONTROLLER FOR THERMOELECTRIC COOLERS FEATURES: > PROPORTIONAL CONTROL > SMALL SIZE > DRIVE CURRENT TO +/- 2 AMPS > OPERATION TO 12 VOLTS > CONTROL ABOVE/BELOW AMBIENT ACTUAL SIZE DESCRIPTION: MAXIMUM RATINGS: The HY-5610 is a subminiature proportional temperature controller for thermoelectric coolers (TEC). This device is intended for “heat or cool” fixed temperature applications where front panel controls and digital readouts are not required. The HY-5610 uses a thermistor bridge to precisely measure and regulate the temperature of a device affixed to a TEC. 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. FIGURE 1 RCH Rating Symbol Value Unit Supply Voltage 1 (Voltage on Pin 8) VDD +20 Volts DC Supply Voltage 2 (Voltage on Pin 10) VS +12 Volts DC Current Sink (Heat and Cool Cycle) IS 2.5 Amperes Maximum Power Dissipation PMAX 6 Watts Operating Temperature (Case) TMAX 120 °C Storage Temperature TSTG -65 to +150 °C SIMPLIFIED SCHEMATIC OF THE HY-5610 SHOWN WITHIN THE DASHED LINES THERMISTOR RCC SIGNAL COMMON RS RG THIS IS THE CURRENT LIMIT RESISTOR FOR THE HEAT CYCLE. RCC THIS IS THE CURRENT LIMIT RESISTOR FOR THE COOLING CYCLE. RT - RL CL RCH VS + THERMOELECTRIC COOLER 7 6 5 3 9 13 1 V/I 20 + PWR. GND PIN N0. 1 VDD + 2 10 11 12 8 +5V 1 V/I 20 +2.5V 10 MΩ +1.25V V/I +1.25V THERMISTOR BRIDGE AMPLIFIER V/I V +2.5V INTEGRATOR The Signal Common and the Power Ground are connected internally to the HY-5610 to avoid ground loops. hytek Microsystems VOLTAGE TO CURRENT CONVERTER POWER STAGES 10KΩ 10KΩ VOLTAGE INVERTER +2.5V 400 Hot Springs Rd. Carson City NV 89706 (702) 883-0820 Fax -0827 www.hytek.com hytek HY-5610 TEC CONTROLLER Microsystems DESCRIPTION OF THE HY-5610 PIN OUTS * Temperature Set Resistor Rs (Pin 1 to Pin 7) The temperature set resistor for the HY-5610 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 10kΩ thermistor is used as the temperature sensing device, a set resistor of approximately 56kΩ will set an operating temperature of -10oC. A graph of Rs vs. set temperature is shown in figure 4 when using a Dale 1M1002 thermistor. * Thermistor, R T (Pin 6 to Pin 7) The thermistor should be located in close proximity to the device being temperature controlled by the TEC. It should be in good thermal contact to avoid stability problems. The HY-5610 has been designed for a negative temperature coefficient thermistor. 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 in which case Rcc & RCH must be interchanged. * Gain Set Resistor, RG (Pin 5 to Pin 6) The ratio of the gain set resistor RG to R L controls the response time of the servo loop. A ratio that is too large can cause slow response and a ratio that is too small can cause loop instability. In most applications RG may not be needed since a 10MΩ resistor is internal to the HY-5610 and generally provides enough gain for good operation. * Loop Stability Network, RL and CL (Pin 3 to Pin 5) 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 it’s final temperature. For example, if the thermal time constant was observed to be 5 seconds, then a 1uF capacitor and a 4.7MΩ could be chosen as the loop stabilizing components. Typical values for loop compensation components are shown in Table 1. Note: The values of RG, RL, and CL are generally selected by experiment. CL should be a low leakage nonpolarized capacitor. * Current Limit Resistors, Rcc & RCH (Pin 1 to Pin 3, and Pin 1 to Pin 2) These resistors limit the maximum current that the HY-5610 can supply to the TEC when in the cooling cycle and in the heating cycle. Rcc limits the maximum current for the cooling cycle and RCH limits the maximum current in the heating cycle. This feature prevents damage to the TEC during turn-on. It is also often desirable to limit the maximum value of heating current as much as 30% less than the maximum cooling current. This is because TECs are much more efficient heating than cooling. Figure 5 shows the approximate values for Rcc & RCH required to program a desired turn-on current. For example an Rcc value of 18KΩ will limit the maximum cooling current to 2 Amperes and an RCH value of 13.5KΩ will limit the maximum heating current to 0.6 Amperes. * VDD (Pin 8 to Pins 11 & 12) +7 < VDD < +20 Volts This input supplies the voltage to the internal circuitry of the HY-5610. The maximum current drain at this terminal is 5mA. * Vs (Pin 10 to Pins 11 & 12) +3 < Vs < +12 Volts This input supplies the voltage to the HY-5610 power drive circuitry. The maximum current drain at this terminal should not exceed 2 Amperes. * Thermoelectric Cooler, TEC (Pin 9 to Pin 13) The cooling lead of the TEC should be connected to Pin 9 and the heating lead should be connected to Pin 13 of the HY-5610. If the temperature of the thermistor is greater than the set temperature at turn-on, maximum cooling current will flow into Pin 9 and out of Pin 13. Conversely, maximum heating current will flow into Pin 13 and out of Pin 9 if the temperature of the thermistor is less than the set temperature at turn-on. The maximum turn-on current is limited by Rcc and RCH. Once the TEC reaches it’s set temperature, the current through the TEC will decrease to exactly the value required to maintain the correct set temperature. hytek Microsystems 400 Hot Springs Rd. Carson City NV 89706 (702) 883-0820 Fax -0827 www.hytek.com hytek HY-5610 TEC CONTROLLER Microsystems HY-5610 CURRENT SOURCE CHARACTERISTICS 11/97 CONSTANT POWER CURVE = 6 WATTS ON RESISTANCE OF CURRENT SINK Figure 2 illustrates the characteristics of the HY-5610 power drive section. It also illustrates the unsafe operating area where the power dissipated in the device exceeds the maximum 6 watt rating. This curve applies for both heating and cooling operation. 2.0 UNSAFE OPERATING AREA Note that the resistance of the power drive section is approximately one ohm when the HY-5610 is fully turned on. 1.0 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 VOLTS FIGURE 2 SUPPLY VOLTAGE ( VS ) PIN 10 TO GROUND (PIN 11 & 12) 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 Tek 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 HY-5610 current source characteristic's define the locus of operation voltage and current for both the HY-5610 and the TEC. In this application the current was limited to 1.8 Amperes when cooling and to 0.6 Amperes when heating by proper selection of RCC & RCH. DETERMINATION OF THE HY-5610 OPERATING POINTS USING LOAD LINES LOAD LINE FOR A ITI Ferro Tec MODEL 6300/018/018A TEC (1.5Ω) 2.0 UNSAFE OPERATING AREA Example 2: 1.0 LOAD LINE FOR A MELCOR MODEL FC 0.45-66-05 TEC 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 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. Once again maximum turn on current is set by proper selection of RCC & RCH. VOLTS FIGURE 3 SUPPLY VOLTAGE ( VS ) PIN 10 TO GROUND (PIN 11 & 12) hytek Microsystems Note that the power dissipated in the HY5610 never exceeds the 6 Watt maximum power dissipation in both of these examples. 400 Hot Springs Rd. Carson City NV 89706 (702) 883-0820 Fax -0827 www.hytek.com hytek HY-5610 TEC CONTROLLER Microsystems 11/97 TEMPERATURE SET RESISTOR Rs vs SET TEMPERATURE APPROXIMATE VALUE OF CURRENT LIMIT SET RESISTOR Rc vs MAXIMUM SINK CURRENT 100 20 19 90 DALE 10KΩ THERMISTOR TYPE 1M1002 80 70 18 17 60 16 50 15 40 14 30 13 20 12 15 11 10 10 -25 -20 -15 FIGURE 4 -10 -5 0 5 10 15 20 25 0 TEMPERATURE °C 0.2 0.4 0.6 FIGURE 5 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 MAXIMUM SINK CURRENT (Is) AMPERES MECHANICAL DIMENSIONS PIN 1 IDENTIFIER TYPICAL RESISTOR AND CAPACITOR VALUES FOR VARIOUS THERMAL TIME CONSTANTS SLOT FOR 2-56 SCREWS 2 PLACES ALUMINUM BASE LEADS ON 0.100" CENTERS THERMAL TIME CONSTANT T (SECONDS) 1 13 2 3 4 HYTEK 12 HY-5610 5 6 1 2 3 5 10 15 20 14 11 0.720" 10 MΩ 20 MΩ 3 MΩ 4.7 MΩ 10 MΩ 15 MΩ 20 MΩ 0.1 µF 0.1 µF 1.0 µF 1.0 µF 1.0 µF 1.0 µF 1.0 µF 100KΩ to 10MΩ NOTES: 8 1. Make sure the heat sink to which the HY-5610 is mounted is flat and clean, otherwise the ceramic substrate may break. 0.110" 0.090" DATE CODE 0.300" Rg TABLE 1 9 7 CL 0.950" 1.150" 10 9326 RL 0.040" 0.600" 0.060" 0.900" 0.220" MAX. 0.720" 0.300" MIN 2. Use a thermal compound such as Dow Corning 340 between the HY-5610 and the heat sink for good thermal conduction. 3. Note that the Pin 1 identifier is shown in a bottom view. From a top view, Pin numbers ascend in clockwise fashion. Specifications Subject to Change Without Notice. hytek Microsystems 400 Hot Springs Rd. Carson City NV 89706 (702) 883-0820 Fax -0827 www.hytek.com