TPS62000, TPS62001, TPS62002, TPS62003

TPS62004, TPS62005, TPS62006, TPS62007, TPS62008

HIGHEFFICIENCY STEPDOWN LOW POWER DCDC CONVERTER

SLVS294C − SEPTEMBER 2000 − REVISED SEPTEMBER 2003

6

POST OFFICE BOX 655303

current flowing backward through the inductance which increases the efficiency. An antiringing switch across

the inductor prevents parasitic oscillation caused by the residual energy stored in the inductance (see Figure

12).

NOTE:

The antiringing switch is only activated in the fixed output voltage versions. It is not enabled for the

adjustable output voltage version TPS62000.

soft start

As the enable pin (EN) goes high, the soft-start function generates an internal voltage ramp. This causes the

start-up current to slowly rise preventing output voltage overshoot and high inrush currents. The soft-start

duration is typical 1 ms (see Figure 13). When the soft-start function is completed, the error amplifier is

connected directly to the internal voltage reference.

enable

Logic low on EN forces the TPS6200x into shutdown. In shutdown, the power switch, drivers, voltage reference,

oscillator, and all other functions are turned off. The supply current is reduced to less than 1

µA in the shutdown

mode.

undervoltage lockout

An undervoltage lockout circuit provides the save operation of the device. It prevents the converter from turning

power good comparator

The power good (PG) comparator has an open drain output capable of sinking typically 10

µA. The PG is only

active when the device is enabled (EN = high). When the device is disabled (EN = low), the PG pin is high

impedance.

The PG output is only valid after a 100

µs delay after the device is enabled and the supply voltage is greater

than 1.2 V. This is only important in cases where the pullup resistor of the PG pin is connected to an external

voltage source which might cause an initial spike (false high signal) within the first 100

µs after the input voltage

exceeds 1.2 V. This initial spike can be filtered with a small R-C filter to avoid false power good signals during

start-up.

If the PG pin is connected to the output of the TPS62000 with a pullup resistor, no initial spike (false high signal)

occurs and no precautions have to be taken during start-up.

The PG pin becomes active high when the output voltage exceeds typically 94.5% of its nominal value. Leave

the PG pin unconnected when not used.

no load operation

In case the converter operates in the forced PWM mode and there is no load connected to the output, the

converter will regulate the output voltage by allowing the inductor current to reverse for a short period of time.