TPS62933O datasheet(16/47 Pages) TI

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(2)

where

• RT = the value of RT timing resistor in kΩ

• fSW = the switching frequency in kHz

Table 8-1. RT Pin Resistor Settings

RT PIN

RESISTANCE

SWITCHING FREQUENCY

Floating

> 280 kΩ

500 kHz

GND

< 1 kΩ

1200 kHz

RT to GND

8.9 kΩ to 111 kΩ

200 kHz to 2200 kHz

Figure 8-3 indicates the required resistor value for RT to set a desired switching frequency.

RT (kohm)

108 118

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

Figure 8-3. Switching Frequency Versus RT

There are four cases where the switching frequency does not conform to the condition set by the RT pin:

• Light load operation (PFM mode)

• Low dropout operation

• Minimum on-time operation

• Current limit tripped

Under all of these cases, the switching frequency folds back, meaning it is less than that programmed by the RT

pin. During these conditions, the output voltage remains in regulation, except for current limit operation.

8.3.6 Enable and Adjusting Undervoltage Lockout

The EN pin provides electrical ON and OFF control of the device. When the EN pin voltage exceeds the enable

threshold voltage, VEN_RISE, the TPS62933 begins operation. If the EN pin voltage is pulled below the disable

threshold voltage, VEN_FALL, the converter stops switching and enters shutdown mode.

The EN pin has an internal pullup current source, which allows the user to float the EN pin to enable the device.

If an application requires control of the EN pin, use open-drain or open-collector or GPIO output logic to interface

with the pin.

The TPS62933 implements internal undervoltage-lockout (UVLO) circuitry on the VIN pin. The device is disabled

when the VIN pin voltage falls below the internal VIN_UVLO threshold. The internal VIN_UVLO threshold has a

hysteresis of typical 300 mV. If an application requires a higher UVLO threshold on the VIN pin, the EN pin can

TPS62933

SLUSEA4A – JUNE 2021 – REVISED DECEMBER 2021

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