Datasheet

Detailed Description
The MAX5389 dual, 256-tap, volatile, low-voltage linear
taper digital potentiometer offers three end-to-end resis-
tance values of 10kΩ, 50kΩ, and 100kΩ. The potenti-
ometer consists of 255 fixed resistors in series between
terminals H_ and L_. The potentiometer wiper, W_, is
programmable to access any one of the 256 tap points on
the resistor string. On power-up, the wiper position is set
to midscale (tap 128).
The potentiometers are programmable independent of
each other. The MAX5389 features an up/down interface.
Up/Down Interface
Logic inputs CS_, UD_, and INC_ determine the wiper
position of the device (Table 1). With CS_ low and UD_
high, a high-to-low (falling edge) transition on INC_ incre-
ments the internal counter which moves the wiper, W_,
closer to H_. When both CS_ and UD_ are low, the falling
edge of INC_ decrements the internal counter and moves
the tap point, W_ closer to L_ (Figure 2). The wiper per-
forms a make-before-break transition ensuring that W_ is
never disconnected from the resistor string during a tran-
sition from one tap point to another. When the wiper is at
either end of the resistor array additional transitions in the
direction of the end point do not change the counter value.
Table 1. Up/Down Control Table
Figure 2. Up/Down Interface Timing Diagram
CS_
UD_ INC_ W_
H X X No change
L L
á
No change
L H
á
No change
L L
â
Decrement
L H
â
Increment
X = Don’t care.
↑ = Low-to-high transition.
↓ = High-to-low transition.
UD_
W_
INC_
CS_
t
CI
t
DI
t
ID
t
IW
t
IC
t
IL
t
IH
MAX5389 Dual, 256-Tap, Volatile, Low-Voltage
Linear Taper Digital Potentiometer
www.maximintegrated.com
Maxim Integrated │ 9