DS3503 Datasheet, PDF (6/12 Pages) Maxim Integrated Products – NV, I2C, Stepper Potentiometer

NV, I²C, Stepper Potentiometer
Detailed Description
The DS3503 contains two potentiometers whose out-
puts can be stepped up and down by configuring the
control registers. One potentiometer, with output RW, is
controlled by the Initial Value Register/Wiper Register
(IVR/WR). The other potentiometer is fixed at setting
40h, and its output is on the Y pin. By using the config-
uration registers and the SYNC pin, the outputs from
these two potentiometers can be stepped up and
down.
Digital Potentiometers
The RW potentiometer consists of 127 resistors in
series connected between the RH and RL pins.
Between each resistance and at the two end points, RH
and RL, solid-state switches enable RW to be connect-
ed within the resistive network. The wiper position and
the output on RW are decoded based on the value in
WR. If RH, RL, and RW are externally connected in a
voltage-divider configuration, the voltage on RW can be
easily calculated using the following equation:
V_RW
=
V_RL
+
WR
127
× (V_RH
−
V_RL )
Where WR is the wiper position in decimal (0–127). The
factory default setting for this potentiometer is 40h.
The Y potentiometer is also referenced to the RH and
RL terminals, but is centered at a 40h setting.
Memory Map
The DS3503 contains three registers for controlling the
outputs of the two potentiometers, pins RW and Y.
Table 1 shows the memory map. IVR/WR is accessed
at register address 00h and contains the power-on and
current values of the RW potentiometer. The Step
Control Register (SCR) controls the stepping function
for both potentiometers. The Control Register (CR) con-
trols the write functionality of the IVR/WR.
Initial Value Register/Wiper Register
(IVR/WR)
Programming IVR sets the initial power-up value of the
RW wiper position. IVR/WR can be visualized as a
volatile register (WR) in parallel with a nonvolatile regis-
ter (IVR). On power-up, the data stored in IVR is loaded
into WR, which sets the position of the potentiometer’s
wiper. The factory default value for IVR is 40h. See the
Stepping section for information about clamping.
Table 1. Memory Map
NAME
ADDRESS
(HEX)
IVR/WR
00h
SCR
01h
CR
02h
Soft-POR
AAh
ACCESS
R/W
R/W
R/W
R/W
NONVOLATILE
Initial Value Register (IVR),
factory setting = 40h
Step Control Register,
factory setting = 00h
Control Register
—
VOLATILE
Wiper Register (WR)
—
—
Soft Power-On Reset
Register
6 _______________________________________________________________________________________