MAX6250 Просмотр технического описания (PDF) - Maxim Integrated
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MAX6250 Datasheet PDF : 11 Pages
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MAX6225/MAX6241/MAX6250
Low-Noise, Precision,
+2.5V/+4.096V/+5V Voltage References
Pin Description
PIN
1, 7, 8
2
NAME
I.C.
IN
FUNCTION
Internally Connected. Do not use.
Positive Power-Supply Input
Noise Reduction. Optional capacitor
3
NR connection for wideband noise reduction.
Leave open if not used (Figure 2).
4
GND Ground
External Trim Input. Allows ±1% output
5
TRIM adjustment (Figure 1). Leave open if not
used.
6
OUT Voltage Reference Output
Detailed Description
Temperature Stability
The MAX6225/MAX6241/MAX6250 are highly stable,
low-noise voltage references that use a low-power
temperature-compensation scheme to achieve laboratory-
standard temperature stability. This produces a nearly flat
temperature curve, yet does not require the power associated
with heated references.
The output voltage can be trimmed a minimum of 0.6%
by connecting a 10kΩ potentiometer between OUT and
GND, and connecting its tap to the TRIM pin, as shown in
Figure 1. The external trimming does not affect temperature
stability.
Noise Reduction
To augment wideband noise reduction, add a 1μF capacitor
to the NR pin (Figure 2). Larger values do not improve
noise appreciably (see Typical Operating Characteristics).
Noise in the power-supply input can affect output noise,
but can be reduced by adding an optional bypass capacitor
to the IN pin and GND.
Bypassing
The MAX6225/MAX6241/MAX6250 are stable with capacitive
load values from 0μF to 100μF, for all values of load
current. Adding an output bypass capacitor can help reduce
noise and output glitching caused by load transients.
Applications Information
Negative Regulator
Figure 3 shows how both a +5V and -5V precision reference
can be obtained from a single unregulated +5V supply.
A MAX681 generates approximately ±9V to operate the
MAX6250 reference and MAX432 inverting amplifier. The
+5V is inverted by the MAX432 chopper-stabilized amplifier.
Resistor R1 is optional, and may be used to trim the
±5V references. R2 and R4 should be matched, both in
absolute resistance and temperature coefficient. R3 is
optional, and is adjusted to set the -5V reference.
8V TO 36V INPUT
IN
MAX6225
REFERENCE OUT
OUT
MAX6241
MAX6250
NR
TRIM
10kΩ
GND
*
1µF
8V TO 36V INPUT
IN
MAX6225
REFERENCE OUT
OUT
MAX6241
MAX6250
NR
TRIM
GND
Figure 1. Output Voltage Adjustment
*OPTIONAL
Figure 2. Noise-Reduction Capacitor
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