AD8156

Rev. 0 | Page 16 of 20

ADDRESS PINS, A[3:0] INPUTS

The AD8156 feature sets can be set port by port or globally.

A[3:2] specify what is being programmed or read back when

the part is being configured port by port. Connectivity, output

current, equalization, or global programming features are

chosen based on the values of A[3:2]. Similarly, A[1:0] address

the port that is being programmed or read back. In global

programming, A[1:0] serve a different function. Refer to Table 9

to Table 15 for programming examples.

DATA PINS, D[3:0] INPUTS/OUTPUTS

In readback mode, the D[3:0] pins are low impedance outputs

indicating the stored values in the memory to be read. The

readback drivers are designed to drive high impedances only,

so external drivers connected to D[3:0] must be disabled during

readback mode.

CONTROL INTERFACE LEVELS

The AD8156 control interface shares the data path supply pins,

more than 3.7 V. Regardless of supply, the logic threshold is

approximately one-half the supply range, allowing the interface

to be used with most LVCMOS- and LVTTL-logic drivers.

Table 7. Dual 2 × 2 Mode Programming Table

Address A[3:0]

Data D[3:0]

Input A3 to Input A0 enable Output 3 to Output 0, respectively.

Input D3 to Input D0 control the connectivity of Output 3 to Output 0, respectively.

1 = Enables the output (for all A[3:0] inputs)

0 = Input 2, 1 = Input 3 (for D2 and D3)

0 = Disables the output (for all A[3:0] inputs)

0 = Input 0, 1 = Input 1 (for D0 and D1)

Table 8. 4 × 4 Mode Programming Table

Mode

Address A[3:0]

Data D[3:0]

0 0 A1 A0

0 D2 D1 D0

Write/Read Connectivity

and Disable

A1 and A0 determine which

output is being programmed.

D1 and D0 determine which input is connected to which output;

D2 determines the enabled/disabled state of that output, with D2 = 1

(enable). When writing or reading, D3 is always 0.

0 1 A1 A0

D3 D2 D1 D0

Write/Read Output

Current Level

A1 and A0 determine which

output is being programmed.

D0 to D3 binarily program the output current level/voltage swing with the

output current = 2 mA + (2 mA × decimal (D[3:0])).

1 0 0 0

0 D2 D1 D0

Broadcast

Connectivity/Disable

D1 and D0 determine which input is connected to all of the outputs.

D2 determines the enabled/disabled state of all outputs with D2 = 1 (enable).

When writing or reading, D3 is always 0.

1 0 0 1

D3 D2 D1 D0

Broadcast Output

Current Level

D0 to D3 binarily program the output current level/voltage swing with the

output current = 2 mA + (2 mA × decimal (D[3:0])). The value is written to

all outputs.

Broadcast EQ Setting

1 0 1 1

D3 D2 D1 D0

Data inputs D0 to D3 set the input equalization level where:

Program EQ Setting

1 1 A1 A0

D3 D2 D1 D0

A1 and A0 determine which

input is being programmed.

D0 to D3 set the input equalization level, where: