TC620 TELCOM | Alldatasheet

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2-15TELCOM SEMICONDUCTOR, INC. TC620 TC621 TC620/1-9 11/4/96 FUNCTIONAL BLOCK DIAGRAM 3HIGH SET LOW SET CONTROL* HIGH LIMIT VDD LOW LIMIT *Suffix code "C" denotes cooling option (high true CONTROL output); suffix code "H" denotes heating option (low true CONTROL output). Q SR Q TC620 HIGH SET LOW SET THERMISTOR CONTROL* HIGH LIMIT LOW LIMIT Temp to Voltage Converter VREF GEN VREF GEN VREF VDD Q SR Q TC621 Thermistor Interface Circuit VREF GEN VREF GEN VREF Ambient Part No. Package Temperature TC621x*EOA 8-Pin SOIC – 40 °C to +85°C TC621x*EPA 8-Pin Plastic DIP – 40 °C to +85°C 5V, DUAL TRIP POINT TEMPERATURE SENSORS

FEATURES

n User-Programmable Hysteresis and Temperature Set Point n Easily Programs with 2 External Resistors n Wide Temperature Detection n External Thermistor for Remote Sensing

APPLICATIONS

n Power Supply Overtemperature Detection n Consumer Equipment n Temperature Regulators n CPU Thermal Protection

ORDERING INFORMATION

Part No. Package Temperature TC620x*COA 8-Pin SOIC 0 °C to +70°C TC620x*CPA 8-Pin Plastic DIP 0 °C to +70°C TC620x*EOA 8-Pin SOIC – 40 °C to +85°C TC620x*EPA 8-Pin Plastic DIP – 40 °C to +85°C TC620CVOA 8-Pin SOIC – 40 °C to +125°C TC621x*COA 8-Pin SOIC 0 °C to +70°C TC621x*CPA 8-Pin Plastic DIP 0 °C to +70°C *The part code will be C or H (see Functional Block Diagram, below, and page 2). GENERAL DESCRIPTION The TC620 and TC621 are programmable logic output temperature detectors designed for use in thermal manage- ment applications. The TC620 features an on-board tem- perature sensor, while the TC621 connects to an external NTC thermistor for remote sensing applications. Both devices feature dual thermal interrupt outputs (HIGH LIMIT and LOW LIMIT), each of which program with a single external resistor. On the TC620, these outputs are driven active (high) when measured temperature equals the user-programmed limits. The CONTROL (hysteresis) out- put is driven high when temperature equals the high limit setting, and returns low when temperature falls below the low limit setting. This output can be used to provide simple ON/OFF control to a cooling fan or heater. The TC621 provides the same output functions except that the logical states are inverted. The TC620/621 are usable over a maximum tempera- ture range of – 40°C to +125°C.

2-16 TELCOM SEMICONDUCTOR, INC. ELECTRICAL CHARACTERISTICS: TA = 25°C, unless otherwise specified. Parameter Conditions Min Typ Max Unit Supply Voltage Range 4.5 — 18 V Supply Current 5V ≤ VDD ≤ 18V — 270 400 µA Output Resistance Output High or Low, 5V ≤ VDD ≤ 18V — 400 1000 Ω Output Current Temp Sensed Source/Sink — — 1 mA Output Current Cool/Heat Source/Sink — — 1 mA Absolute Accuracy T = Programmed Temperature T – 3 T T + 3 °C ABSOLUTE MAXIMUM RATINGS* Package Power Dissipation (TA ≤ 70°C) Derating Factors DD +0.3V) Operating Temperature *Static-sensitive device. Unused devices must be stored in conductive material. Protect devices from static discharge and static fields. Stresses above those listed under "Absolute Maximum Ratings" may cause perma- nent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operation sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. VDD VDD GND GND LOW LIMIT LOW LIMIT CONTROL CONTROL NC NC LOW SET LOW SET HIGH SET HIGH SET HIGH LIMIT HIGH LIMIT VDD GND LOW LIMIT CONTROL NC LOW SET HIGH SET HIGH LIMIT VDD GND LOW LIMIT CONTROL NC LOW SET HIGH SET HIGH LIMIT 1 8 2 7 3 6 4 5 TC621xCPA TC621xEPA TC621xCOA TC621xEOA 1 8 2 7 3 6 4 5 TC620xCOA TC620xEOA TC620CVOA TC620xCPA TC620xEPA PIN CONFIGURATIONS (DIP and SOIC) 5V, DUAL TRIP POINT TEMPERATURE SENSORS TC620 TC621

2-18 TELCOM SEMICONDUCTOR, INC. 5V, DUAL TRIP POINT TEMPERATURE SENSORS TC620 TC621 Using The TC621 The TC621 operation is identical to that of the TC620, but requires an external NTC thermistor. Use the resistance versus temperature curve of the thermistor to determine the values of the programming resistors. Note that the pin numbers for the HIGH SET and LOW SET programming resistors for the TC621 are reversed versus that of the TC620 (i.e. the resistor value on HIGH SET [pin 2] should always be lower than the one connected to LOW SET [pin 3]). Also note that the outputs of the TC621 are LOW TRUE when used with an NTC thermistor. TYPICAL NTC THERMISTOR 01 0 2 0 3 0 4 05 0 100 TEMPERATURE ( °C) 150 200 250 300 350 THERMISTOR RESISTANCE (k Ω ) Figure 4. Typical Thermistor Resistance vs. Temperature of approximately 100kΩ at 25°C is recommended. (pin 3) sets the low temperature trip point to +41°C. Dual Speed Temperature Control The Dual Speed Temperature Control uses a TC620 and a TC4469 quad driver. Two of the drivers are configured in a simple oscillator. When the temperature is below the LOW TEMP set point, the output of the driver is OFF. When the temperature exceeds the LOW TEMP set point, the TC4469 gates the oscillator signal to the outputs of the driver. This square wave signal modulates the remaining outputs and drives the motor at a low speed. If this speed cannot keep the temperature below the HIGH TEMP set point, then the driver turns on continuously which increases the fan speed to high. The TC620 will monitor the tempera- ture and only allow the fan to operate when needed, and at the required speed to maintain the desired temperature. A higher power option can be designed by adding a resistor and a power MOSFET. Temperature Controlled Fan In this application, a high and a low temperature is selected by two ‘set’ resistors. The TC620 monitors the ambient temperature and turns the FET switch on when the temperature exceeds the HIGH TEMP set point. The fan remains on until the temperature decreases to the LOW TEMP set point. This provides the hysteresis. In this appli- cation, the fan turns on only when required. The TC621 uses an external thermistor to monitor the ambient temperature. This adds one part, but allows more flexibility in location of the sensor. TC620/621 Outputs Both devices have complimentary output stages. They are rated at a source or sink current of 1mA maximum.

2-20 TELCOM SEMICONDUCTOR, INC. Figure 8. TC620 Heating/Cooling Application