Datasheet

LTC2600/LTC2610/LTC2620
13
2600fe
OPERATION
32-bit sequence. The 32-bit word is required for daisy-
chain operation, and is also available to accommodate
microprocessors which have a minimum word width of
16 bits (2 bytes).
Daisychain Operation
The serial output of the shift register appears at the SDO
pin. Data transferred to the device from the SDI input is
delayed 32 SCK rising edges before being output at the
next SCK falling edge.
The SDO output can be used to facilitate control of multiple
serial devices from a single 3-wire serial port (i.e., SCK,
SDI and CS/LD). Such a “daisychain” series is confi gured
by connecting SDO of each upstream device to SDI of the
next device in the chain. The shift registers of the devices
are thus connected in series, effectively forming a single
input shift register which extends through the entire
chain. Because of this, the devices can be addressed and
controlled individually by simply concatenating their input
words; the fi rst instruction addresses the last device in
the chain and so forth. The SCK and CS/LD signals are
common to all devices in the series.
In use, CS/LD is fi rst taken low. Then the concatenated
input data is transferred to the chain, using SDI of the
fi rst device as the data input. When the data transfer is
complete, CS/LD is taken high, completing the instruction
sequence for all devices simultaneously. A single device
can be controlled by using the no-operation command
(1111) for the other devices in the chain.
C3
COMMAND ADDRESS DATA (16 BITS)
C2
C1
C0
A3
A2
A1
A0
D13D14D15
D12
D11 D10 D9 D8
D7
D6
D5 D4 D3 D2 D1
D0
2600 TBL01
MSB
LSB
C3
COMMAND ADDRESS DATA (14 BITS + 2 DON’T-CARE BITS)
C2
C1
C0
A3
A2
A1
A0
D13
D12
D11 D10 D9 D8
D7
D6
D5 D4 D3 D2 D1
D0 X X
2600 TBL02
MSB
LSB
C3
COMMAND ADDRESS DATA (12 BITS + 4 DON’T-CARE BITS)
C2
C1
C0
A3
A2
A1
A0
D11 D10 D9 D8
D7
D6
D5 D4 D3 D2 D1
D0 X XXX
2600 TBL03
MSB
LSB
INPUT WORD (LTC2600)
INPUT WORD (LTC2610)
INPUT WORD (LTC2620)