REF5025-HT
SBOS502D – SEPTEMBER 2009 – REVISED APRIL 2012
APPLICATION INFORMATION
The REF5025 is a low-noise, precision bandgap
voltage reference that is specifically designed for
excellent initial voltage accuracy and drift.
shows a simplified block diagram of the REF5025.
V
IN
USING THE TRIM/NR PIN
The REF5025 provides a very accurate voltage
output. However, V
OUT
can be adjusted to reduce
noise and shift the output voltage from the nominal
value by configuring the trim and noise reduction pin
(TRIM/NR, pin 5). The TRIM/NR pin provides a ±15-
mV adjustment of the device bandgap, which
produces a ±15-mV change on the V
OUT
pin.
shows a typical circuit using the TRIM/NR
pin to adjust V
OUT
. When using this technique, the
temperature coefficients of the resistors can degrade
the temperature drift at the output.
+V
SUPPLY
REF5025
司
公
限
有 2
件
技 83 器
科 16 元
子 29 子
电 -8 电
创 55 温
德 07 高
鸿 话 油
圳 电 石
深 系 理
联 代
业
专
R2
R1
aT
(10mA
at +25°C)
TEMP
aT
R4
V
OUT
10kW
1.2V
R3
TRIM/NR
R5
60kW
1kW
REF5025
DNC
DNC
NC
V
IN
TEMP
GND
V
OUT
GND TRIM/NR
10kW
1kW
470W
Figure 24. REF5025 Simplified Block Diagram
BASIC CONNECTIONS
shows the typical connections for the
REF5025. A supply bypass capacitor ranging
between 1
μF
to 10
μF
is recommended. A 1-μF to
50-μF, low-ESR output capacitor (C
L
) must be
connected from V
OUT
to GND. The ESR value should
be less than or equal to 1.5
Ω.
The ESR minimizes
gain peaking of the internal 1.2-V reference and thus
reduces noise at the V
OUT
pin.
+V
SUPPLY
Figure 26. V
OUT
Adjustment Using TRIM/NR Pin
The REF5025 allows access to the bandgap through
the TRIM/NR pin. Placing a capacitor from the
TRIM/NR pin to GND (as
illustrates) in
combination with the internal 1-kΩ resistor creates a
low-pass filter that lowers the overall noise measured
on the V
OUT
pin. A capacitance of 1
μF
is suggested
for a low-pass filter with a corner frequency of
14.5 Hz. Higher capacitance results in a lower cutoff
frequency.
+V
SUPPLY
REF5025
DNC
DNC
C
BYPASS
1
m
F to 10
m
F
V
IN
NC
TEMP
V
OUT
V
OUT
REF5025
GND TRIM/NR
C
L
1
m
F to 50
m
F
DNC
DNC
V
IN
NC
TEMP
V
OUT
GND TRIM/NR
Figure 25. Basic Connections
C1
1
m
F
SUPPLY VOLTAGE
The REF5025 features extremely low dropout
voltage. For loaded conditions, a typical dropout
voltage versus load plot is shown in
of
Typical Characteristics.
Figure 27. Noise Reduction Using TRIM/NR Pin
Copyright © 2009–2012, Texas Instruments Incorporated
9
TI [ TEXAS INSTRUMENTS ]
