SET

GND

OT

VCC

HYST

0.1 …F

RSET

VIA to ground plane

VIA to power plane

150

11

TMP709

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SBOS583B – DECEMBER 2011 – REVISED DECEMBER 2016

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9 Power Supply Recommendations

The TMP709 low supply current and supply range allow this device to be powered from many sources. Any

significant noise on the VCC pin can result in a trip-point error. Minimize this noise by low-pass filtering the

device supply (VCC) using a 150-Ω resistor and a 0.1-μF capacitor.

10 Layout

10.1 Layout Guidelines

The TMP709 is extremely simple to lay out. Figure 7 shows the recommended board layout.

10.2 Layout Example

Figure 7. Recommended Layout

10.3 Thermal Considerations

The TMP709 quiescent current is typically 40 μA. The device dissipates negligible power when the output drives

a high-impedance load. Thus, the die temperature is the same as the package temperature. In order to maintain

accurate temperature monitoring, provide a good thermal contact between the TMP709 package and the device

being monitored. The rise in die temperature as a result of self-heating is given by Equation 2:

ΔTJ = PDISS × θJA

where

•

PDISS = power dissipated by the device.

•

θJA = package thermal resistance. Typical thermal resistance for SOT-23 package is 217.9°C/W.

(2)

To limit the effects of self-heating, keep the output current at a minimum level.