CLK

DIN

CS_N

I0

DOUT

T1

T2

T3

T4

T6

T7

T8

T9

TS

TH

T5

T10

0

1

0

1

0

1

0

1

CFG

1

0

MODE

0

1

HIGH IMPEDANCE

I2

I1

TS

A0

A1

T

TS

LMH6580, LMH6581

SNOSAY4C – AUGUST 2007 – REVISED MAY 2013

www.ti.com

Figure 67. Timing Diagram for Addressed Mode

Table 4. Addressed Mode Word Format(1)

Output Address

Input Address

TRI-STATE

LSB

MSB

LSB

MSB

1 = TRI-STATE

0 = On

0

1

2

3

4

5

(1)

Bit 0 is first bit clocked into device.

DAISY CHAIN OPTION IN SERIAL MODE

The LMH6580/LMH6581 supports daisy chaining of the serial data stream between multiple chips. This feature is

available only in the Serial Programming Mode. To use this feature serial data is clocked into the first chip DIN

pin, and the next chip DIN pin is connected to the DOUT pin of the first chip. Both chips may share a chip select

signal, or the second chip can be enabled separately. When the chip select pin goes low on both chips a double

length word is clocked into the first chip. As the first word is clocking into the first chip the second chip is

receiving the data that was originally in the shift register of the first chip (invalid data). When a full 16 bits have

been clocked into the first chip the next clock cycle begins moving the first frame of the new configuration data

into the second chip. With a full 32 clock cycles both chips have valid data and the chip select pin of both chips

should be brought high to prevent the data from overshooting. A configure pulse will activate the new

configuration on both chips simultaneously, or each chip can be configured separately. The mode, chip select,

configure and clock pins of both chips can be tied together and driven from the same sources.

SPECIAL CONTROL PINS

The LMH6580/LMH6581 have two special control pins that function independent of the serial control bus. One of

these pins is the reset (RST) pin. The RST pin is active high meaning that at logic 1 level the chip is configured

with all outputs disabled and in a high impedance state. The RST pin programs all the registers with input

address 0 and all the outputs are turned off. In this configuration the device draws only 11mA. The RST pin can

be used as a shutdown function to reduce power consumption. The other special control pin is the broadcast

(BCST) pin. The BCST pin is also active high and sets all the outputs to the on state connected to input 0. This is

sometimes referred to as broadcast mode, where input 0 is broadcast to all eight outputs.

24

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