max5405eubt Maxim Integrated Products, Inc., max5405eubt Datasheet - Page 8

• Manufacturer Part Number: max5405eubt
• Description: Dual, 256-tap, Low-drift, Digital Potentiometers In 10-?max
• Manufacturer: Maxim Integrated Products, Inc.

of each SCLK pulse
have been shifted in, they are latched into the appropri-
ate potentiometer control register when CS transitions
from low to high. Note that if CS is not kept low during
the entire data stream, the data will be corrupted and
the device will need to be reloaded.
The first bit A0 (address bit) is used to address one or
the other of the potentiometers for programming.
Potentiometer control register A is selected for writing
when A0 is ‘zero’, and potentiometer control register B
is selected when A0 is one.
The MAX5403/MAX5404/MAX5405 feature POR circuitry
that sets the wiper to the midscale position at power-up.
The MAX5403/MAX5404/MAX5405 are intended for a
variety of circuits where accurate, fine-tuning adjustable
resistance is required, such as in adjustable voltage or
adjustable gain circuit configurations. It is primarily used
in either a potentiometer divider or a variable resistor
configuration.
Dual 256-Tap, Low-Drift,
Digital Potentiometers in 10-µMAX
Figure 2. Potentiometer Serial Data Timing Circuit
Figure 3. Detailed Serial Interface Timing Diagram
8
SCLK
DIN
CS
_______________________________________________________________________________________
t
CSO
Applications Information
t
CSS
(Figure 2). After all the data bits
t
DS
t
DH
CS
SCLK
TIME
DIN
1ST CLOCK PULSE
MSB
A0
t
CL
D7
D6
t
CH
D5
D4
D3
Figure 5 shows the MAX5403/MAX5404/MAX5405 being
used with a MAX4250 low-noise op amp to fine tune a
current to voltage converter. Pins H
MAX5403/MAX5404/MAX5405 3-terminal potentiometer
(only pin W
nected to the node between R3 and R2 (pin L
nected to ground). Circuit space is minimized due to
both devices’ packaging.
Figure 6 shows how to use the MAX5403/MAX5404/
MAX5405 to digitally adjust the gain of a noninverting op
amp configuration. In Figure 6a, connect the MAX5403/
MAX5404/MAX5405 as a 2-terminal variable resistor in
series with a resistor to ground to form the adjustable
gain control of a noninverting amplifier.
Similarly, Figure 6b shows how to use the MAX5403/
MAX5404/MAX5405 as a 3-terminal potentiometer. In
this application the MAX5403/MAX5404/MAX5405 low
5ppm/°C ratiometric tempco allows for a very stable
adjustable gain-configuration overtemperature.
Adjustable Current to Voltage Converter
D2
D1
9TH CLOCK PULSE
POT REGISTER LOADED
A
LSB
D0
of the 2-terminal variable resistor) are con-
t
CP
Adjustable Gain Amplifier
t
CSH
t
CS1
B
and W
t
CSW
X
B
is con-
of the