|Description||200-mA, Low-Quiescent Current, Ultra-Low-Noise, High-PSRR Low-Dropout Linear Regulator|
|TPS79901-EP Datasheet PDF : 27 Pages |
SBVS330A – SEPTEMBER 2017 – REVISED OCTOBER 2017
Feature Description (continued)
7.3.3 Start Up
The TPS79901 uses a start-up circuit to quickly charge the noise reduction capacitor, CNR, if present (see the
Functional Block Diagram). This circuit allows for the combination of very low output noise and fast start-up
times. The NR pin is high impedance so a low leakage CNR capacitor must be used; most ceramic capacitors are
appropriate for this configuration.
Note that for fastest start-up, apply VIN first, and then drive the enable pin (EN) high. If EN is tied to IN, start-up is
somewhat slower. The start-up switch is closed for approximately 135 μs. To ensure that CNR is fully charged
during start-up, use a 0.01-μF or smaller capacitor.
7.3.4 Undervoltage Lockout (UVLO)
The TPS79901 use an undervoltage lockout circuit to keep the output shut off until internal circuitry is operating
properly. The UVLO circuit has a deglitch feature so that undershoot transients are typically ignored on the input
if these transients are less than 50 μs in duration.
7.4 Device Functional Modes
Driving EN over 1.2-V turns on the regulator. Driving EN below 0.4 V puts the regulator into shutdown mode,
thus reducing the operating current to 150 nA, nominal.
Copyright © 2017, Texas Instruments Incorporated
Product Folder Links: TPS79901-EP
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