TPS79601DCQ datasheet(21/50 Pages) TI2

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7.1.4 Adjustable Configuration

The output voltage of the TPS79601 adjustable regulator is programmed using an external resistor divider, as

Figure 7-1 shows.

OUT

2.2 F

GND

OUT

1 F

TPS79601

OUTPUT VOLTAGE

PROGRAMMING GUIDE

OUTPUT

VOLTAGE

1.8 V

3.6 V

14.0 kW

57.9 kW

30.1 kW

33 pF

15 pF

Figure 7-1. Typical Application, Adjustable Output

The output voltage is calculated using Equation 2:

OUT

REF

u ¨

(2)

where:

• VREF = 1.2246 V typical (the internal reference voltage)

For the TPS796 (legacy chip), resistors R1 and R2 should be chosen for approximately 40μA divider current.

Lower value resistors can be used for improved noise performance, but the device wastes more power. Higher

values should be avoided, as leakage current at FB increases the output voltage error.

The recommended design procedure is to choose R2 = 30.1 kΩ to set the divider current at 40 μA, C1 = 15 pF

for stability, and then calculate R1 using Equation 3:

OUT

REF

(3)

Similarly, for the TPS796 (new chip), to disregard the effect of the FB pin current error term and to achieve best

accuracy, choose R2 to be equal to or smaller than 550 kΩ so that the current flowing through R1 and R2 is

at least five times larger than the IFB current listed in the Electrical Characteristics table. Lowering the value of

R2 increases the immunity against noise injection. Increasing the value of R2 reduces the quiescent current for

achieving higher efficiency at low load currents. Equation 4 calculates the setting that provides the maximum

feedback divider series resistance.

(R1 + R2) ≤ VOUT / (IFB × 5)

(4)

7.1.5 Load Transient Response

The load-step transient response is the output voltage response by the LDO to a step in load current, whereby

output voltage regulation is maintained. There are two key transitions during a load transient response: the

transition from a light to a heavy load and the transition from a heavy to a light load. The regions shown in Figure

7-2 are broken down as follows. Regions A, E, and H are where the output voltage is in steady-state.

tAt

tDt

tEt

tCt

tGt

tHt

Figure 7-2. Load Transient Waveform

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TPS796

SLVS351Q – SEPTEMBER 2002 – REVISED JUNE 2025

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