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Q1V

(2 V/div)

(2 A/div)

t − Time − 40 ms/div

PTH12010W , PTH12010L

SLTS205G – JUNE 2003 – REVISED FEBRUARY 2007

Figure 13. Power-Up from Track Control

NOTE:

If a prebias condition is not present, it is highly recommended that the Track control

pin be used for controlled power-up and power-down. If Track control is not used, the

output voltage starts up and overshoots by as much as 10%, before settling at the

output voltage setpoint.

How Auto-Track™ Works

Auto-Track works by forcing the module output voltage to follow a voltage presented at the Track control pin

(1)

This control range is limited to between 0 V and the module set-point voltage. Once the track-pin voltage is

raised above the set-point voltage, the module output remains at its set-point

(2)

. As an example, if the Track pin

of a 2.5-V regulator is at 1 V, the regulated output is 1 V. If the voltage at the Track pin rises to 3 V, the

regulated output does not go higher than 2.5 V.

When under Auto-Track control, the regulated output from the module follows the voltage at its Track pin on a

volt-for-volt basis. By connecting the Track pin of a number of these modules together, the output voltages follow

a common signal during power up and power down. The control signal can be an externally generated master

ramp waveform, or the output voltage from another power supply circuit

(3)

. For convenience, the Track input

incorporates an internal RC-charge circuit. This operates off the module input voltage to produce a suitable

rising waveform at power up.

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