Datasheet

Detailed Description
Temperature Stability
The MAX6225/MAX6241/MAX6250 are highly stable,
low-noise voltage references that use a low-power tem-
perature-compensation scheme to achieve laborato-
rystandard 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 tempera-
ture stability.
Noise Reduction
To augment wideband noise reduction, add a 1μF capaci-
tor 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 capaci-
tor to the IN pin and GND.
Bypassing
The MAX6225/MAX6241/MAX6250 are stable with capaci-
tive 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 refer-
ence can be obtained from a single unregulated +5V sup-
ply. A MAX681 generates approximately ±9V to operate
the MAX6250 reference and MAX432 inverting amplifier.
The +5V is inverted by the MAX432 chopperstabilized
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.
Figure 1. Output Voltage Adjustment Figure 2. Noise-Reduction Capacitor
PIN NAME FUNCTION
1, 7, 8 I.C. Internally Connected. Do not use.
2 IN Positive Power-Supply Input
3 NR
Noise Reduction. Optional capacitor
connection for wideband noise reduction.
Leave open if not used (Figure 2).
4 GND Ground
5 TRIM
External Trim Input. Allows ±1% output
adjustment (Figure 1). Leave open if not
used.
6 OUT Voltage Reference Output
IN
8V TO 36V INPUT
REFERENCE OUT
OUT
TRIM
10kΩ
NR
GND
MAX6225
MAX6241
MAX6250
IN
8V TO 36V INPUT
REFERENCE OUT
OUT
TRIM
NR
*OPTIONAL
*
1µF
GND
MAX6225
MAX6241
MAX6250
MAX6225/MAX6241/MAX6250 Low-Noise, Precision,
+2.5V/+4.096V/+5V Voltage References
www.maximintegrated.com
Maxim Integrated │ 9
Pin Description