Datasheet

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
DNC
TEMP
V
OUT
V
IN
GND
DNC
NC
TRIM/NR
REF50xx
+V
SUPPLY
10kW
1kW
470kW
DNC
TEMP
V
OUT
V
IN
GND
DNC
NC
TRIM/NR
REF50xx
C
BYPASS
1 Fto10 Fm m
C
L
1 Fto50 Fm m
+V
SUPPLY
V
OUT
DNC
TEMP
V
OUT
V
IN
GND
DNC
NC
TRIM/NR
REF50xx
C1
1 Fm
+V
SUPPLY
REF5010, REF5020
REF5025, REF5030
REF5040, REF5045, REF5050
SBOS410E –JUNE 2007–REVISED JUNE 2010 www.ti.com
APPLICATION INFORMATION
The REF50xx is family of low-noise, precision requirement of 2.7V, these references can be
bandgap voltage references that are specifically operated with a supply of 200mV above the output
designed for excellent initial voltage accuracy and voltage in an unloaded condition. For loaded
drift. Figure 28 shows a simplified block diagram of conditions, a typical dropout voltage versus load plot
the REF50xx. is shown in Figure 6 of the Typical Characteristics.
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 1mF to 10mF is recommended. A 1mF to
The REF50xx allows access to the bandgap through
50mF 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
minimize noise, the recommended ESR of C
L
is
low-pass filter. A capacitance of 1mF creates a
between 1Ω and 1.5Ω.
low-pass 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
extremely low dropout voltage. With the exception of
Figure 31. Noise Reduction Using the TRIM/NR
the REF5020, which has a minimum supply
Pin
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Product Folder Link(s): REF5010 REF5020 REF5025 REF5030 REF5040 REF5045 REF5050