LTC2751-14 Linear Technology Corporation, LTC2751-14 Datasheet - Page 9

• Manufacturer Part Number: LTC2751-14
• Description: Ltc2751-14 - Current Output 14-bit Softspan Dacs With Parallel I/o
• Manufacturer: Linear Technology Corporation

PIN FUNCTIONS
R
tied to the negative input of the external reference invert-
ing amplifi er.
R
Amplifi er. Normally tied to the external reference voltage
V
±15V.
S2 (Pin 3): Span I/O Bit 2. Pins S0, S1 and S2 are used to
program and to read back the output range of the DAC.
I
to GND.
NC (Pin 5): No Connection. Must be tied to GND, provides
necessary shielding for I
D3-D11 (Pins 6-14): LTC2751-12 Only. DAC Input/Output
Data Bits. These I/O pins set and read back the DAC code.
D11 is the MSB.
D5-D13 (Pins 6-14): LTC2751-14 Only. DAC Input/Output
Data Bits. These I/O pins set and read back the DAC code.
D13 is the MSB.
D7-D15 (Pins 6-14): LTC2751-16 Only. DAC Input/Output
Data Bits. These I/O pins set and read back the DAC code.
D15 is the MSB.
V
Requires a 0.1µF bypass capacitor to GND.
GND (Pin 16): Ground. Tie to ground.
⎯ C ⎯ L ⎯ R (Pin 17): Asynchronous Clear. When ⎯ C ⎯ L ⎯ R is taken
to a logic low, the data registers are reset to the zero-volt
code for the present output range (V
MSPAN (Pin 18): Manual Span Control Pin. MSPAN is used
to confi gure the LTC2751 for operation in a single, fi xed
output range. When confi gured for single-span operation,
the output range is set via hardware pin strapping. The
span input and DAC registers are transparent and do not
respond to write or update commands.
To confi gure the part for single-span use, tie MSPAN
directly to V
(SoftSpan confi guration), the output ranges are set and
verifi ed by using write, update and read operations. See
Manual Span Confi guration in the Operation section.
OUT2
REF
DD
COM
IN
(Pin 2): Input Resistor for External Reference Inverting
(Pin 15): Positive Supply Input 2.7V ≤ V
and to R
(Pin 4): DAC Current Output Complement. Tie I
(Pin 1): Center Tap Point of R
DD
OFS
. If MSPAN is instead connected to GND
(Pin 37). Typically 5V; accepts up to
OUT2
.
IN
OUT
and REF. Normally
= 0V).
DD
≤ 5.5V.
OUT2
MSPAN must be connected either directly to GND (Soft-
Span confi guration) or V
D0-D2 (Pins 19-21): LTC2751-12 Only. DAC Input/Output
Data Bits. These I/O pins set and read back the DAC code.
D0 is the LSB.
D0-D4 (Pins 19-23): LTC2751-14 Only. DAC Input/Output
Data Bits. These I/O pins set and read back the DAC code.
D0 is the LSB.
D0-D6 (Pins 19-25): LTC2751-16 Only. DAC Input/Output
Data Bits. These I/O pins set and read back the DAC code.
D0 is the LSB.
NC (Pins 22-27): LTC2751-12 Only. No Connection.
NC (Pins 24-27): LTC2751-14 Only. No Connection.
NC (Pins 26, 27): LTC2751-16 Only. No Connection.
⎯ D /S (Pin 28): Data/Span Select. This pin is used to select
activation of the data or span I/O pins (D0 to D15 or S0
to S2, respectively), along with their respective dedicated
registers, for write or read operations. Update operations
ignore ⎯ D /S, since all updates affect both data and span
registers. For single-span operation, tie ⎯ D /S to GND.
READ (Pin 29): Read Pin. When READ is asserted high,
the data I/O pins (D0-D15) or span I/O pins (S0-S2)
output the contents of the selected register (see Table 1).
For single-span operation, readback of the span I/O pins
is disabled.
UPD (Pin 30): Update and Buffer Select Pin. When READ
is held low and UPD is asserted high, the contents of the
input registers (both data and span) are copied into their
respective DAC registers. The output of the DAC is updated,
refl ecting the new DAC register values.
When READ is held high, the update function is disabled
and the UPD pin functions as a buffer selector—logic low
to select the input register, high for the DAC register. See
Readback in the Operation section.
⎯ W ⎯ R (Pin 31): Active Low Write Pin. A Write operation
copies the data present on the data or span I/O pins (D0-
D15 or S0-S2, respectively) into the input register. When
READ is high, the Write function is disabled.
S0 (Pin 32): Span I/O Bit 0. Pins S0, S1 and S2 are used to
program and to read back the output range of the DAC.
DD
(single-span confi guration).
LTC2751
9
2751f