cat522 Catalyst Semiconductor, cat522 Datasheet - Page 6

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cat522

Manufacturer Part Number
cat522
Description
Configured Digitally Programmable Potentiometer Dpp? Programmable Voltage Applications
Manufacturer
Catalyst Semiconductor
Datasheet
CAT522
PIN DESCRIPTION
DEVICE OPERATION
The CAT522 is a dual 8-bit configured digitally
programmable potentiometer (DPP) whose outputs
can be programmed to any one of 256 individual
voltage steps.
settings are retained in non-volatile memory and will
not be lost when power is removed from the chip.
Upon power up the DPPs return to the settings stored
in non-volatile memory. Each DPP can be written to
and read from independently without effecting the
output voltage during the read or write cycle. Each
output can also be
stored output setting, which is useful for testing new
output settings before storing them in memory.
DIGITAL INTERFACE
The CAT522 employs a 3 wire serial, Microwire-like
control interface consisting of Clock (CLK), Chip
Select (CS) and Data In (DI) inputs.
operations, address and data are shifted in LSB first.
In addition, all digital data must be preceded by a logic
“1” as a start bit. The DPP address and data are
clocked into the DI pin on the clock’s rising edge.
When sending multiple blocks of information a
minimum of two clock cycles is required between the
last block sent and the next start bit.
Multiple devices may share a common input data line
by selectively activating the CS control of the desired
IC. Data Outputs (DO) can also share a common line
Doc. No. MD-2004 Rev. G
Pin
10
11
12
13
14
1
2
3
4
5
6
7
8
9
RDY/BSY
PROG
V
V
Name
V
V
V
V
GND
CLK
V
DO
REFH2
REFH1
CS
REFL1
REFL2
OUT2
OUT1
DI
DD
¯¯¯¯
Once programmed, these output
Function
Power supply positive
Clock input pin
Ready/Busy output
Chip select
Serial data input pin
Serial data output pin
EEPROM Programming Enable
Input
Power supply ground
Minimum DPP1 output voltage
Minimum DPP2 output voltage
DPP2 output
DPP1 output
Maximum DPP2 output voltage
Maximum DPP1 output voltage
adjusted without altering the
For all
6
DPP addressing is as follows:
because the DO pin is Tri-Stated and returns to a high
impedance when not in use.
CHIP SELECT
Chip Select (CS) enables and disables the CAT522’s
read and write operations. When CS is high data may
be read to or from the chip, and the Data Output (DO)
pin is active. Data loaded into the DPP control regis–
ters will remain in effect until CS goes low. Bringing
CS to a logic low returns all DPP outputs to the
settings stored in non-volatile memory and switches
DO to its high impedance Tri-State mode.
Because CS functions like a reset the CS pin has
been desensitized with a 30 ns to 90 ns filter circuit to
prevent noise spikes from causing unwanted resets
and the loss of volatile data.
CLOCK
The CAT522’s clock controls both data flow in and out
of the IC and non-volatile memory cell programming.
Serial data is shifted into the DI pin and out of the DO
pin on the clock’s rising edge. While it is not neces–
sary for the clock to be running between data
transfers, the clock must be operating in order to write
to non-volatile memory, even though the data being
saved may already be resident in the DPP wiper
control register.
DPP OUTPUT
V
V
OUT1
OUT2
Characteristics subject to change without notice
A0
0
1
© Catalyst Semiconductor, Inc.
A1
1
1

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