Datasheet

1V/div
Time(400 s/div)m
V
IN
0.1 Fm
1 Fm
10 Fm
V
IN
REF33xx
GND
V
OUT
1.2V
Bandgap
REF33xx
V
IN
V
OUT
V
OUT
V
IN
C
BYPASS
1 Fto10 F
(recommended)
m m
C
L
0.1 Fto10 Fm m
GND
REF3312 , REF3318 , REF3320 , REF3325 , REF3330 , REF3333
SBOS392D –AUGUST 2007–REVISED JUNE 2014 www.ti.com
9 Detailed Description
9.1 Overview
The REF33xx is a family of low-power, precision band-gap voltage references that are specifically designed for
extremely low dropout, excellent initial voltage accuracy with a high output current. A simplified block diagram of
the REF33xx is shown in the Functional Block Diagram section. Figure 17 shows the typical connections for the
REF33xx. A supply bypass capacitor ranging between 1 μF to 10 μF is recommended. The total capacitive load
at the output must be between 0.1 μF to 10 μF to ensure output stability.
Figure 17. Basic Connections
9.2 Functional Block Diagram
9.3 Feature Description
9.3.1 Start-Up Time
The REF33xx features an advanced start-up circuit. Start-up time is almost independent of load (with a 0.1-μF to
10-μF load). Upon startup, the current boost circuit forces the output voltage. When the preset voltage is
reached, the REF33xx switches to the second stage of output circuitry to precisely set the output voltage.
Figure 18 shows the start-up time of the REF3325 for three different capacitive loads. In all three cases, the
output voltage settles within 2 ms.
Figure 18. Start-Up Time
10 Submit Documentation Feedback Copyright © 2007–2014, Texas Instruments Incorporated
Product Folder Links: REF3312 REF3318 REF3320 REF3325 REF3330 REF3333