MAX6325 Maxim, MAX6325 Datasheet - Page 8

• Manufacturer Part Number: MAX6325
• Description: 1ppm/C / Low-Noise / +2.5V/+4.096V/+5V Voltage References
• Manufacturer: Maxim

_____________________Pin Description
1ppm/°C, Low-Noise, +2.5V/+4.096V/+5V
Voltage References
The MAX6325/MAX6341/MAX6350 are highly stable,
low-noise voltage references that use a low-power tem-
perature-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 tem-
perature stability.
Figure 1. Output Voltage Adjustment
8
_______________Detailed Description
1, 7, 8
PIN
_______________________________________________________________________________________
2
3
4
5
6
NAME
TRIM
GND
OUT
NR
I.C.
NR
IN
8V TO 36V INPUT
MAX6325
MAX6341
MAX6350
Internally Connected. Do not use.
Positive Power-Supply Input
Noise Reduction. Optional capacitor
connection for wideband noise
reduction. Leave open if not used
(Figure 2).
Ground
External Trim Input. Allows ±1%
output adjustment (Figure 1).
Leave open if not used.
Voltage Reference Output
GND
IN
Temperature Stability
TRIM
OUT
FUNCTION
REFERENCE OUT
10k
To augment wideband noise reduction, add a 1µF
capacitor to the NR pin (Figure 2). Larger values do not
improve noise appreciably (see
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.
The MAX6325/MAX6341/MAX6350 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.
Figure 3 shows how both a +5V and -5V precision ref-
erence can be obtained from a single, unregulated +5V
supply. A MAX681 generates approximately ±9V to
operate the MAX6350 reference and MAX400 inverting
amplifier. The +5V is inverted by the ultra-low offset
MAX400 op amp. 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 2. Noise-Reduction Capacitor
__________Applications Information
*
*OPTIONAL
1 F
NR
8V TO 36V INPUT
MAX6325
MAX6341
MAX6350
GND
IN
Negative Regulator
Noise Reduction
Typical Operating
TRIM
OUT
REFERENCE OUT
Bypassing