LTC1662IMS8 Просмотр технического описания (PDF) - Linear Technology
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LTC1662IMS8 Datasheet PDF : 12 Pages
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LTC1662
U
OPERATIO
Table 1. DAC Control Functions
CONTROL
INPUT REGISTER
A3 A2 A1 A0
STATUS
0000
No Change
DAC REGISTER
STATUS
No Update
POWER-DOWN STATUS
(SLEEP/WAKE)
No Change
0001
Load DAC A
No Update
No Change
0010
Load DAC B
No Update
No Change
1000
No Change
Update Outputs
Wake
1001
Load DAC A
Update Outputs
Wake
1010
Load DAC B
Update Outputs
Wake
1101
No Change
No Update
Wake
1110
No Change
No Update
Sleep
1111
Load DACs A, B
with Same
10-Bit Code
Update Outputs
Wake
Note: All control codes other than those shown are undefined and not subject to test.
COMMENTS
No Operation. Power-Down Status Unchanged
(Part Stays In Wake or Sleep Mode)
Load Input Register A with Data. DAC Outputs
Unchanged. Power-Down Status Unchanged
Load Input Register B with Data. DAC Outputs
Unchanged. Power-Down Status Unchanged
Load Both DAC Regs with Existing Contents of Input
Regs. Outputs Update. Part Wakes Up
Load Input Reg A. Load DAC Regs with New Contents
of Input Reg A and Existing Contents of Reg B. Outputs
Update. Part Wakes Up
Load Input Reg B. Load DAC Regs with Existing Contents
of Input Reg A and New Contents of Reg B. Outputs
Update. Part Wakes Up
Part Wakes Up. Input and DAC Regs Unchanged. DAC
Outputs Reflect Existing Contents of DAC Regs
Part Goes to Sleep. Input and DAC Regs Unchanged. DAC
Outputs Set to High Impedance State
Load Both Input Regs. Load Both DAC Regs with New
Contents of Input Regs. Outputs Update. Part Wakes Up
Transfer Function
The transfer function for the LTC1662 is:
VOUT(IDEAL)
=
k
1024
VREF
where k is the decimal equivalent of the binary DAC input
code D9-D0 and VREF is the voltage at REF (Pin 4).
Power-On Reset
The LTC1662 actively clears the outputs to zero scale
when power is first applied, making system initialization
consistent and repeatable.
Power Supply Sequencing
The voltage at REF (Pin 4) should be kept within the range
–0.3V ≤ VREF ≤ VCC + 0.3V (see Absolute Maximum
Ratings). Particular care should be taken during power
supply turn-on and turn-off sequences, when the voltage
at VCC (Pin 6) is in transition. If it is not possible to
sequence the supplies, clamp the voltage at REF by
connecting a Schottky diode between Pin 4 (anode) and
Pin 6 (cathode).
Serial Interface
See Table 2. The 16-bit Input word consists of the 4-bit
Control code, the 10-bit Input code and two don’t-care bits.
Table 2. LTC1662 Input Word
Input Word
A3 A2 A1 A0 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 X1 X0
Control Code
Input Code
Don’t
Care
AftertheInputwordisloadedintotheregister(seeFigure␣ 1),
it is internally converted from serial to parallel format. The
parallel 10-bit-wide Input code data path is then buffered
by two latch registers.
8
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