LTC2264-14(RevB) データシートの表示（PDF） - Linear Technology
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LTC2264-14 Datasheet PDF : 32 Pages
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LTC2265-14/
LTC2264-14/LTC2263-14
APPLICATIONS INFORMATION
Serial data transfer starts when CS is taken low. The data
on the SDI pin is latched at the first 16 rising edges of
SCK. Any SCK rising edges after the first 16 are ignored.
The data transfer ends when CS is taken high again.
The first bit of the 16-bit input word is the R/W bit. The
next seven bits are the address of the register (A6:A0).
The final eight bits are the register data (D7:D0).
If the R/W bit is low, the serial data (D7:D0) will be written
to the register set by the address bits (A6:A0). If the R/W bit
is high, data in the register set by the address bits (A6:A0)
will be read back on the SDO pin (see the Timing Diagrams
section). During a readback command the register is not
updated and data on SDI is ignored.
The SDO pin is an open-drain output that pulls to ground
with a 200Ω impedance. If register data is read back through
SDO, an external 2k pull-up resistor is required. If serial
data is only written and readback is not needed, then SDO
can be left floating and no pull-up resistor is needed. Table
4 shows a map of the mode control registers.
Software Reset
If serial programming is used, the mode control registers
should be programmed as soon as possible after the power
supplies turn on and are stable. The first serial command
must be a software reset which will reset all register data
bits to logic 0. To perform a software reset, bit D7 in the
reset register is written with a logic 1. After the reset SPI
write command is complete, bit D7 is automatically set
back to zero.
Table 4. Serial Programming Mode Register Map (PAR/SER = GND)
REGISTER A0: RESET REGISTER (ADDRESS 00h)
D7
D6
D5
D4
D3
D2
D1
RESET
X
X
X
X
X
X
Bit 7
RESET
Software Reset Bit
0 = Not Used
1 = Software Reset. All Mode Control Registers Are Reset to 00h. The ADC is momentarily placed in SLEEP mode.
This Bit Is Automatically Set Back to Zero at the End of the SPI Write Command.
The Reset Register is Write Only.
Bits 6-0
Unused, Don’t Care Bits.
REGISTER A1: FORMAT AND POWER-DOWN REGISTER (ADDRESS 01h)
D7
D6
D5
D4
D3
D2
D1
DCSOFF
RAND
TWOSCOMP
SLEEP
NAP_2
X
X
Bit 7
DCSOFF Clock Duty Cycle Stabilizer Bit
0 = Clock Duty Cycle Stabilizer On
1 = Clock Duty Cycle Stabilizer Off. This is Not Recommended.
Bit 6
RAND
Data Output Randomizer Mode Control Bit
0 = Data Output Randomizer Mode Off
1 = Data Output Randomizer Mode On
Bit 5
TWOSCOMP Two’s Complement Mode Control Bit
0 = Offset Binary Data Format
1 = Two’s Complement Data Format
Bits 4, 3, 0
SLEEP: NAP_2: NAP_1 Sleep/Nap Mode Control Bits
000 = Normal Operation
0X1 = Channel 1 in Nap Mode
01X = Channel 2 in Nap Mode
1XX = Sleep Mode. Both Channels are disabled
Note: Any Combination of Channels Can Be Placed in Nap Mode.
Bits 1, 2
Unused, Don’t Care Bit
D0
X
D0
NAP_1
24
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