LTC2600 Linear Technology, LTC2600 Datasheet - Page 11

• Manufacturer Part Number: LTC2600
• Description: (LTC2600 - LTC2620) 3V/5V Octal 12-bit Rail-to-rail DAC
• Manufacturer: Linear Technology

OPERATIO
INPUT WORD (LTC2600)
INPUT WORD (LTC2610)
INPUT WORD (LTC2620)
Daisy-Chain 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 “daisy chain” series is configured
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 con-
trolled individually by simply concatenating their input
words; the first 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 first taken low. Then the concatenated
input data is transferred to the chain, using SDI of the first
device as the data input. When the data transfer is com-
plete, 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
C3
C3
COMMAND
COMMAND
COMMAND
C2
C2
C2
C1 C0
C1 C0
C1 C0
U
A3
A3
A3
ADDRESS
ADDRESS
ADDRESS
A2
A2
A2
A1
A1
A1
A0
A0 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2
A0
MSB
MSB
MSB
D15
D11 D10 D9 D8 D7 D6 D5 D4 D3 D2
D14
D13
D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2
Power Down Mode
Command 0100
instruction (see Table 1). Any or all DACs may be powered
down by selecting the appropriate DAC address (n). In this
mode, the digital interface stays active while the analog
circuits are disabled. The static power consumption of the
digital interface is leakage current only. The reference
input and analog outputs are set in a high impedance state,
although the DAC feedback resistors are still in place
loading the DAC outputs with 90k to ground. As shown
in Table 1, any or all of the DACs can be powered back up
by executing an update command to the selected DAC
which will power up that DAC and update its output with
the last loaded DAC word.
Voltage Outputs
Each of the 8 rail-to-rail amplifiers contained in these parts
has guaranteed load regulation when sourcing or sinking
up to 15mA at 5V (7.5mA at 3V).
Load regulation is a measure of the amplifier’s ability to
maintain the rated voltage accuracy over a wide range of
load conditions. The measured change in output voltage
per milliampere of forced load current change is ex-
pressed in LSB/mA.
DATA (14 BITS + 2 DON’T-CARE BITS)
DATA (12 BITS + 4 DON’T-CARE BITS)
LTC2600/LTC2610/LTC2620
DATA (16 BITS)
b
is reserved for the special “power down”
D1 D0
LSB
D1 D0
X
LSB
X
D1 D0
X
X
2600 TBL01
2600 TBL02
2600 TBL03
LSB
X
X
11
2600f