9.4 Device Functional Modes

9.4.1 Basic Connections

Figure 9-1 shows the typical connections for the REF35. TI recommends a supply bypass capacitor (CIN)

ranging from 0.1 μF to 10 μF. A 0.1 μF to 10 μF output capacitor (CL) must be connected from REF to GND. The

equivalent series resistance (ESR) value of CL must be lower than 400 mΩ to ensure output stability.

VIN

EN

CIN

CL

GND

GND

GND

GND

GND

NR

VREF

Optional

AVDD

REF

REF35

Figure 9-1. Basic Connections

9.4.2 Start-Up

Figure 9-2 shows the start-up behavior of REF35250 device with 1 μF load capacitance. REF35 device ensures

the output voltage settles to the expected output voltage within specified accuracy without oscillations. The

start-up time is dependent on the output voltage variant, output capacitance and NR pin capacitance. Higher

capacitance leads to longer start-up time.

Time (5 ms/div)

VIN (1.5V/div)

VREF (1.25V/div)

Figure 9-2. REF35250 Start-Up Behavior, CL = 1 μF

9.4.3 Output Transient Behavior

The REF35 output buffer is capable of sourcing 10 mA load current as well as sink 5 mA of load current. The

output stage is designed using class AB architecture with ultra-low quiescent current. This architecture avoids

the dead zone around the no load condition. The output buffer uses a fast start-up implementation to achieve

2ms typical turn-on time at CL = 1 μF and no-load current condition.

Figure 9-3 and Figure 9-4 show the output settling behavior for light load transient and high load transient

respectively.

REF35

SNAS809A – DECEMBER 2021 – REVISED AUGUST 2022

www.ti.com

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