LM235A

Part: LM135 / LM135A / LM235 / LM235A / LM335 / LM335A (LMx35, LMx35A) — Texas Instruments

Type: Precision Analog Temperature Sensor (2-terminal zener type)

Description: Two-terminal precision temperature sensor with a 10 mV/K output, operating from 400 μA to 5 mA with less than 1 Ω dynamic impedance, directly calibrated to the Kelvin scale, with 1°C initial accuracy available.

Operating Conditions:

• Supply voltage: not applicable (2-terminal device, forward/reverse current biased)
• Operating current: 0.4–5 mA (1 mA nominal)
• Operating temperature: grade-dependent, continuous: LM135/LM135A -55 to 150 °C; LM235/LM235A -40 to 125 °C; LM335/LM335A -40 to 100 °C

Absolute Maximum Ratings:

• Reverse current: 15 mA
• Forward current: 10 mA
• Storage temperature: -65 to 150 °C (8-pin SOIC); -60 to 150 °C (TO / TO-92)

Key Specs:

• Output voltage temperature coefficient: 10 mV/°C (typ)
• Operating output voltage at 25°C, IR = 1 mA: 2.97–2.99 V (LM135A/LM235A); 2.95–3.01 V (LM135/LM235 and LM335A); 2.92–3.04 V (LM335)
• Uncalibrated error at 25°C, IR = 1 mA (max): 1 °C (LM135A/LM235A); 3 °C (LM135/LM235); 3 °C (LM335A); 6 °C (LM335)
• Error with 25°C calibration over TMIN–TMAX (max): 1 °C (LM135A/LM235A); 1.5 °C (LM135/LM235); 1 °C (LM335A); 2 °C (LM335)
• Output voltage change with current, 400 μA ≤ IR ≤ 5 mA: 2.5 mV typ / 10 mV max (LM135/235); 3 mV typ / 14 mV max (LM335)
• Dynamic impedance at IR = 1 mA: 0.5 Ω typ (LM135/235); 0.6 Ω typ (LM335)
• Time constant: 80 s (still air), 10 s (100 ft/min air), 1 s (stirred oil)
• Time stability at TC = 125°C: 0.2 °C/khr typ
• Thermal resistance RθJA: 165 °C/W (SOIC), 202 °C/W (TO-92), 400 °C/W (TO-46)

Features:

• Directly calibrated to the Kelvin temperature scale
• 1°C initial accuracy available
• Operates from 400 μA to 5 mA
• Less than 1 Ω dynamic impedance
• Easily calibrated with a single-point adjustment via the ADJ pin
• 200°C overrange
• Low cost

Applications:

• Power supplies
• Battery management
• HVAC
• Appliances

Package:

• TO-46 (3) — 4.699 mm × 4.699 mm (LM135, LM135A)
• TO-92 (3) — 4.30 mm × 4.30 mm (LM235, LM235A)
• SOIC (8) — 4.90 mm × 3.91 mm (LM335, LM335A)

LM135, LM135A, LM235, LM235A, LM335, LM335A

SNIS160E -MAY 1999-REVISED FEBRUARY 2015

• Power Supplies
• Battery Management
• HVAC
• Appliances

TO-46 (NDV) 3 Pins Bottom View

TO-92 (LP) 3 Pins Bottom View

See (1) .

over operating free-air temperature range (unless otherwise noted) (1)(2)(3)(4)

over operating free-air temperature range (unless otherwise noted)

To insure good sensing accuracy, several precautions must be taken. Like any temperature-sensing device, selfheating can reduce accuracy. The LM135 should be operated at the lowest current suitable for the application. Sufficient current, of course, must be available to drive both the sensor and the calibration pot at the maximum operating temperature as well as any external loads.

If the sensor is used in an ambient where the thermal resistance is constant, self-heating errors can be calibrated out. This is possible if the device is run with a temperature-stable current. Heating will then be proportional to zener voltage and therefore temperature. This makes the self-heating error proportional to absolute temperature the same as scale factor errors.