LTC2755
9
2755f
Midscale Glitch
TYPICAL PERFORMANCE CHARACTERISTICS
T
A
= 25°C, unless otherwise noted.
LTC2755-12, LTC2755-14, LTC2755-16
PIN FUNCTIONS
S2 (Pin 1): Span I/O Bit 2. Pins S0, S1 and S2 are used
to program and to read back the output ranges of the
DACs.
I
OUT2A
(Pin 2): DAC A Current Output Complement. Tie
I
OUT2A
to ground.
GND (Pin 3): Shield Ground, provides necessary shielding
for I
OUT2A
. Tie to ground.
D3-D11 (Pins 4-12): LTC2755-12 Only. DAC Input/Output
Data Bits. These I/O pins set and read back the DAC code.
D11 is the MSB.
D5-D13 (Pins 4-12): LTC2755-14 Only. DAC Input/Output
Data Bits. These I/O pins set and read back the DAC code.
D13 is the MSB.
D7-D15 (Pins 4-12): LTC2755-16 Only. DAC Input/Output
Data Bits. These I/O pins set and read back the DAC code.
D15 is the MSB.
GND (Pin 13): Shield Ground, provides necessary shielding
for I
OUT2D
. Tie to ground.
I
OUT2D
(Pin 14): DAC D Current Output Complement. Tie
I
OUT2D
to ground.
V
DD
(Pin 15): Positive Supply Input; 2.7V ≤ V
DD
≤ 5.5V.
Requires a 0.1µF bypass capacitor to GND.
A2 (Pin 16): DAC Address Bit 2. See Table 3.
A1 (Pin 17): DAC Address Bit 1. See Table 3.
A0 (Pin 18): DAC Address Bit 0. See Table 3.
GND (Pin 19): Ground. Tie to ground.
CLR (Pin 20): Asynchronous Clear. When CLR is taken
to a logic low, the data registers are reset to the zero-volt
code (V
OUT
= 0V) for the present output range.
REFD (Pin 21): Reference Input for DAC D. The imped-
ance looking into this pin is 10k to ground. For normal
operation tie this pin to the negative reference voltage at
the output of reference inverting amplifier A2 (see Typical
Applications). Typically –5V; accepts up to ±15V.
R
OFSD
(Pin 22): Bipolar Offset Network for DAC D. This
pin provides the translation of the output voltage range for
bipolar spans. Accepts up to ±15V; for normal operation
tie to the positive reference voltage at R
IN2
(Pin 32). The
impedance looking into this pin is 20k to ground.
R
FBD
(Pin 23): DAC D Feedback Resistor. For normal
operation tie to the output of the I/V converter amplifi er
for DAC D (see Typical Applications). The DAC output
current from I
OUT1D
fl ows through the feedback resistor
to the R
FBD
pin. The impedance looking into this pin is
10k to ground.
I
OUT1D
(Pin 24): DAC D Current Output. This pin is a virtual
ground when the DAC is operating and should reside at 0V.
For normal operation tie to the negative input of the I/V
converter amplifi er for DAC D (see Typical Applications).
500ns/DIV
UPD
5V/DIV
GATED
SETTLING
WAVEFORM
250µV/DIV
2755 G10
USING LT1469 AMP
C
FEEDBACK
= 12pF
0V TO 10V STEP
Settling 0V to 10V
500ns/DIV
2755 G20
RISING MAJOR CARRY TRANSITION.
FALLING TRANSITION IS SIMILAR OR BETTER.
UPD
5V/DIV
V
OUT
2mV/DIV
UNIPOLAR 5V OUTPUT RANGE
LT1469 OUTPUT AMPLIFIER
C
FEEDBACK
= 27pF
V
DD
= 5V, V
REF
= 5V
1nV • s TYP
