Datasheet

MAX5408–MAX5411
Dual, Audio, Log Taper Digital Potentiometers
6 _______________________________________________________________________________________
Detailed Description
Digital Serial Interface
An SPI-compatible serial interface controls the
MAX5408–MAX5411. The input word to the device is
eight bits long, composed of three address bits (A0,
A1, and A2), followed by five data bits, with MSB first
(see Tables 1 and 2). The first three address bits set
the value of internal registers. The five data bits control
the wiper position. For certain commands, some of the
five data bits are “don’t cares”, but must be sent to the
device.
The serial data is listed in Tables 1 and 2.
The control code determines:
• Potentiometer to update or register to set.
• Data for mute register (Tables 3 and 4).
• Data for zero-crossing detection register (Tables 5
and 6).
The data bits control the position of the wiper (Table 7).
A logic low on the chip-select input (CS) enables the
device’s serial interface. A logic high on CS disables
the interface control circuitry. See Figure 1 for serial-
interface timing description.
8-BIT SERIAL WORD
A0 A1 A2 D4–D0
FUNCTION
00 05-bit DAC data Set position of wiper W0A
00 15-bit DAC data No change
01 05-bit DAC data Set position of wiper W1A
01 15-bit DAC data No change
10 04-bit mute data, D0 = “don’t care” Data for mute register (see Table 3)
10 1
4-bit zero-crossing detection data,
D0 = “don’t care”
Data for zero-crossing detection register
(see Table 5)
11 000000
Readback contents of wiper register for W0A
at DOUT
11 000001 No change
11 000010
Readback contents of wiper register for W1A
at DOUT
11 000011 No change
11 000100 Readback contents of mute register at DOUT
11 000101
Readback contents of zero-crossing detection
register at DOUT
11 1D4 = 0, D3–D0 = “don’t care”
Immediate update then analog power-down
when zero crossing is enabled. No effect
when zero crossing is disabled.
Table 1. Serial Interface Programming Commands for MAX5408/MAX5410
t
CSS
t
CL
t
CH
t
DS
t
DH
t
CP
t
CSH
t
CSI
t
CSW
t
DO
t
IW
WIPER
DOUT
DIN
SCLK
CS
DOUT
DIN
SCLK
CS
Figure 1. Serial Timing Diagram