Datasheet
DNC
TEMP
V
OUT
V
IN
GND
DNC
NC
TRIM/NR
REF50xx
C1
1 Fm
+V
SUPPLY
DNC
TEMP
V
OUT
V
IN
GND
DNC
NC
TRIM/NR
REF50xx
C
BYPASS
1 Fto10 Fm m
C
L
1 Fto50 Fm m
+V
SUPPLY
V
OUT
DNC
TEMP
V
OUT
V
IN
GND
DNC
NC
TRIM/NR
REF50xx
+V
SUPPLY
10kW
1kW
470kW
R5
60kW
REF50xx
TEMP
V
OUT
GND
TRIM/NR
V
IN
aT
aT
(10 Am
at+25 C)°
R2 R1
R3
R4
10kW
1kW
1.2V
REF5010, REF5020
REF5025, REF5030
REF5040, REF5045, REF5050
SBOS410F –JUNE 2007–REVISED DECEMBER 2013
www.ti.com
APPLICATION INFORMATION
requirement of 2.7V, these references can be
The REF50xx is family of low-noise, precision
operated with a supply of 200mV above the output
bandgap voltage references that are specifically
voltage in an unloaded condition. For loaded
designed for excellent initial voltage accuracy and
conditions, a typical dropout voltage versus load plot
drift. Figure 28 shows a simplified block diagram of
is shown in Figure 6 of the Typical Characteristics.
the REF50xx.
OUTPUT ADJUSTMENT USING THE TRIM/NR
PIN
The REF50xx provides a very accurate, factory-
trimmed voltage output. However, V
OUT
can be
adjusted using the trim and noise reduction pin
(TRIM/NR, pin 5). Figure 30 shows a typical circuit
that allows an output adjustment of ±15mV
Figure 28. REF50xx Simplified Block Diagram
BASIC CONNECTIONS
Figure 30. V
OUT
Adjustment Using the TRIM/NR
Figure 29 shows the typical connections for the
Pin
REF50xx. A supply bypass capacitor ranging
between 1μF to 10μF is recommended. A 1μF to The REF50xx allows access to the bandgap through
50μF output capacitor (C
L
) must be connected from the TRIM/NR pin. Placing a capacitor from the
V
OUT
to GND. The ESR value of C
L
must be less than TRIM/NR pin to GND (see Figure 31) in combination
or equal to 1.5Ω to ensure output stability. To with the internal R
3
and R
4
resistors creates a low-
minimize noise, the recommended ESR of C
L
is pass filter. A capacitance of 1μF creates a low-pass
between 1Ω and 1.5Ω. filter with the corner frequency between 10Hz and
20Hz. Such a filter decreases the overall noise
measured on the V
OUT
pin by half. Higher
capacitance results in a lower filter cutoff frequency,
further reducing output noise. Note that use of this
capacitor increases startup time.
Figure 29. Basic Connections
SUPPLY VOLTAGE
The REF50xx family of voltage references features
Figure 31. Noise Reduction Using the TRIM/NR
extremely low dropout voltage. With the exception of
Pin
the REF5020, which has a minimum supply
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Product Folder Links: REF5010 REF5020 REF5025 REF5030 REF5040 REF5045 REF5050