ltc1654cgn-trpbf Linear Technology Corporation, ltc1654cgn-trpbf Datasheet - Page 9

• Manufacturer Part Number: ltc1654cgn-trpbf
• Description: Ltc1654 - Dual 14-bit Rail-to-rail Dac In 16-lead Ssop Package
• Manufacturer: Linear Technology Corporation

OPERATIO
Voltage Output
The LTC1654 comes complete with rail-to-rail voltage
output buffer amplifiers. These amplifiers will swing to
within a few millivolts of either supply rail when unloaded
and to within a 450mV of either supply rail when sinking
or sourcing 5mA.
There are two GAIN configuration modes for the LTC1654:
a) GAIN of 1: (X
b) GAIN of 1/2: (X
The LTC 1654 has two SPEED modes: A FAST mode and
a SLOW mode. When operating in the FAST mode, the
output amplifiers will settle in 3µs (typ) to 14 bits on a 4V
output swing. In the SLOW mode, they will settle in 8.5µs.
V
V
OUT
OUT
= (1/2)(V
= (V
REFHI
1
U
REFHI
/X
– V
1
/X
1/2
1/2
REFLO
– V
tied to REFLO)
tied to V
REFLO
)(CODE/16384) + V
)(CODE/16384) + V
OUT
)
REFLO
REFLO
The total supply current is 930µA in the FAST mode and
540µA in the SLOW mode. The output noise voltage
density at 10kHz is 170nV/√Hz in SLOW mode and
150nV/√Hz in FAST mode.
Power Down
Each DAC can also be independently powered down to less
than 5µA/DAC of supply current. The reference pin also
goes into a high impedance state when the DAC is powered
down and the reference current will drop to below 0.1µA.
The amplifiers’ output stage is also three-stated but the
V
connected to them resulting in an effective resistance from
V
X
REFLO. Because of this resistance, V
when the DAC is powered down and V
OUT
OUT
1
/X
1/2
to REFLO. This resistance is typically 90k when the
pins still have the internal gain-setting resistors
pin is tied to V
OUT
and 36k when X
OUT
OUT
will go to V
LTC1654
1
is unloaded.
/X
1/2
is tied to
REFLO
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