X9460 Datasheet, PDF (4/16 Pages) Intersil Corporation – Dual Audio Control Digitally Controlled Potentiometer

X9460
Detailed Pin Description
Host Interface Pins
SERIAL CLOCK (SCL)
The SCL input clocks data into and out of the X9460.
SERIAL DATA (SDA)
SDA is a bidirectional pin used to transfer data into and out
of the device. It is an open drain output and may be wire-
ORed with any number of open drain or open collector
outputs. An open drain output requires the use of a pull-up
resistor. For selecting typical values, refer to the guidelines
for calculating typical values on the bus pull-up resistors
graph.
DEVICE ADDRESS (A₁ - A₀)
The Address inputs are used to set the least significant 2 bits
of the 8-bit Slave Byte Address. A match in the slave
address serial data stream must be made with the Address
input in order to initiate communication with the X9460. Up to
4 X9460s may be connected to a single I²C serial bus and
written to (NOTE: you cannot read from more than one
device on the same 2-wire bus). If left floating, these pins are
internally pulled to ground.
Slave Byte (bits, MSB-LSB) = 0101 0 A₁ A₀ R/W
Potentiometer Pins
R_H-LEFT, R_L-LEFT, R_H-RIGHT, R_L-RIGHT
The R_H and R_L inputs are equivalent to the terminal
connections on either end of a mechanical potentiometer.
R_W-LEFT, R_W-RIGHT
The wiper outputs are equivalent to the wiper output of a
mechanical potentiometer.
Supply Pins
ANALOG SUPPLY V- AND V+
The positive power supply for the DCP analog control
section is connected to V+. The negative power supply for
the DCP analog control section is connected to V-.
DIGITAL SUPPLIES V_CC, V_SS
The power supplies for the digital control sections.
Power-up and Down Recommendations
There are no restrictions on the power-up condition of V_CC,
V+ and V- and the voltages applied to the potentiometer pins
provided that the V_CC and V+ are more positive or equal to
the voltage at R_H, R_L, and R_W, ie. V_CC, V+ > R_H, R_L, R_W. At
all times, the voltages on the potentiometer pins must be
less than V+ and more than V-.
The following V_CC ramp rate spec is always in effect.
0.2 V/ms < V_CC ramp < 50 V/ms
The V_SS pin is always connected to the system common or
ground. V_H, V_L, V_W are the voltages on the R_H, R_L, and R_W
potentiometer pins.
X9460 Principles of Operation
The X9460 is a highly integrated microcircuit incorporating
two resistor arrays with their associated registers, counters
and the serial interface logic providing direct communication
between the host and the DCP potentiometers. This section
provides detailed description as following:
- Resistor Array Description
- Serial Interface Description
- Command Set and Register Information Description
Resistor Array Description
The X9460 is comprised of two resistor arrays. Each array
contains 31 discrete resistive segments that are connected
in series. The physical ends of each array are equivalent to
the fixed terminals of a mechanical potentiometer (R_H and
R_L inputs). Tables 1 and 2 provide a description of the step
size and tap positions.
At both ends of each array and between each resistor
segment is a CMOS switch connected to the wiper (R_W)
output. Within each individual array only one switch may be
turned on at a time. These switches are controlled by the
Wiper Counter Register (WCR). The five bits of the WCR are
decoded to select, and enable, one of thirty-two switches.
TABLE 1. TOTAL -62dB RANGE PLUS MUTE POSITION
STEP SIZE
# OF STEPS
-1dB
- 2dB
- 3dB
- 4dB
Mute
11 steps
10 steps
5 steps
4 steps
1 step
TABLE 2. WIPER TAP POSITION vs dB
TAP POSITION, n
dB
MIN/MAX dB
for n = 20 to 31
n - 31
-11/0
for n = 10 to 19
2n-51
-31/-13
for n = 5 to 9
3n-61
-46/-34
for n = 1 to 4
4n-66
-62/-50
n=0
-92
-92
4
FN8203.2
October 17, 2005