LM26LVCISDX-080SLASHNOPB datasheet(20/33 Pages) TI1

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TJ = TA + TJA (VDDIQ) + (VDD - VTEMP) IL

LM26LV

SNIS144F – JULY 2007 – REVISED FEBRUARY 2013

www.ti.com

CLOAD

Minimum RS

1.1 nF to 99 nF

3 k

100 nF to 999 nF

1.5 k

μF

800

VOLTAGE SHIFT

The LM26LV/LM26LV-Q1 is very linear over temperature and supply voltage range. Due to the intrinsic behavior

of an NMOS/PMOS rail-to-rail buffer, a slight shift in the output can occur when the supply voltage is ramped

over the operating range of the device. The location of the shift is determined by the relative levels of VDD and

VTEMP. The shift typically occurs when VDD − VTEMP = 1.0V.

This slight shift (a few millivolts) takes place over a wide change (approximately 200 mV) in VDD or VTEMP. Since

the shift takes place over a wide temperature change of 5°C to 20°C, VTEMP is always monotonic. The accuracy

specifications in the Electrical Characteristics table already includes this possible shift.

Mounting and Temperature Conductivity

The LM26LV/LM26LV-Q1 can be applied easily in the same way as other integrated-circuit temperature sensors.

It can be glued or cemented to a surface.

The best thermal conductivity between the device and the PCB is achieved by soldering the DAP of the package

to the thermal pad on the PCB. The temperatures of the lands and traces to the other leads of the

LM26LV/LM26LV-Q1 will also affect the temperature reading.

Alternatively, the LM26LV/LM26LV-Q1 can be mounted inside a sealed-end metal tube, and can then be dipped

into a bath or screwed into a threaded hole in a tank. As with any IC, the LM26LV/LM26LV-Q1 and

accompanying wiring and circuits must be kept insulated and dry, to avoid leakage and corrosion. This is

especially true if the circuit may operate at cold temperatures where condensation can occur. If moisture creates

a short circuit from the VTEMP output to ground or VDD, the VTEMP output from the LM26LV/LM26LV-Q1 will not be

correct. Printed-circuit coatings are often used to ensure that moisture cannot corrode the leads or circuit traces.

The thermal resistance junction-to-ambient (

θJA) is the parameter used to calculate the rise of a device junction

temperature due to its power dissipation. The equation used to calculate the rise in the LM26LV/LM26LV-Q1's

die temperature is

(9)

where TA is the ambient temperature, IQ is the quiescent current, IL is the load current on the output, and VO is

the output voltage. For example, in an application where TA = 30 °C, VDD = 5 V, IDD = 9 μA, Gain 4, VTEMP = 2231

mV, and IL = 2 μA, the junction temperature would be 30.021 °C, showing a self-heating error of only 0.021°C.

Since the LM26LV/LM26LV-Q1's junction temperature is the actual temperature being measured, care should be

taken to minimize the load current that the VTEMP output is required to drive. If The OVERTEMP output is used

with a 100 k pull-up resistor, and this output is asserted (low), then for this example the additional contribution is

[(152° C/W)x(5V)2/100k] = 0.038°C for a total self-heating error of 0.059°C. Table 2 shows the thermal resistance

of the LM26LV/LM26LV-Q1.

Table 2. LM26LV/LM26LV-Q1 Thermal Resistance

Device Number

NS Package Number

Thermal Resistance (

θJA)

LM26LVCSID/LM26LVQCISD

NGF0006A

152° C/W

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