LM137HVQML

SNVS314A – DECEMBER 2010 – REVISED APRIL 2013

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When power is dissipated in an IC, a temperature gradient occurs across the IC chip affecting the individual IC circuit

components. With an IC regulator, this gradient can be especially severe since power dissipation is large. Thermal regulation

is the effect of these temperature gradients on output voltage (in percentage output change) per Watt of power change in a

specified time. Thermal regulation error is independent of electrical regulation or temperature coefficient, and occurs within 5

ms to 50 ms after a change in power dissipation. Thermal regulation depends on IC layout as well as electrical design. The

step of power is applied. The LM137HV's specification is 0.02%/W, max.

This performance is thus well inside the specification limit of 0.02%/W x 10W = 0.2% max. When the 10W pulse is ended, the

thermal regulation again shows a 3 mV step as the LM137HV chip cools off. Note that the load regulation error of about 8 mV

(0.08%) is additional to the thermal regulation error. In Figure 5, when the 10W pulse is applied for 100 ms, the output drifts

only slightly beyond the drift in the first 10 ms, and the thermal error stays well within 0.1% (10 mV).

Figure 8. Adjustable Current Regulator

**When C2 is larger than 10

shorted

Figure 9. Negative Regulator with Protection Diodes

*Use resistors with good tracking TC < 25 ppm/°C

Figure 10. High Stability

−40V Regulator

8

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