CAT522 datasheet(6/15 Pages) CATALYST

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CAT522

Doc. No. MD-2004 Rev. G

Characteristics subject to change without notice

PIN DESCRIPTION

Name

Function

VDD

Power supply positive

CLK

Clock input pin

RDY/BSY

¯¯¯¯ Ready/Busy output

Chip select

Serial data input pin

Serial data output pin

PROG

EEPROM Programming Enable

Input

GND

Power supply ground

VREFL1

Minimum DPP1 output voltage

VREFL2

Minimum DPP2 output voltage

VOUT2

DPP2 output

VOUT1

DPP1 output

VREFH2

Maximum DPP2 output voltage

VREFH1

Maximum DPP1 output voltage

DPP addressing is as follows:

DPP OUTPUT

VOUT1

VOUT2

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.

Once programmed, these output

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

adjusted without altering the

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.

For all

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

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.

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