LTC2298 Linear Technology, LTC2298 Datasheet - Page 21

• Manufacturer Part Number: LTC2298
• Description: (LTC2296 - LTC2298) Low Power 3V ADCs
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
between the digital outputs and sensitive input circuitry.
The output should be buffered with a device such as an
ALVCH16373 CMOS latch. For full speed operation the
capacitive load should be kept under 10pF.
Lower OV
from the digital outputs.
Data Format
Using the MODE pin, the LTC2298/LTC2297/LTC2296
parallel digital output can be selected for offset binary or
2’s complement format. Note that MODE controls both
Channel A and Channel B. Connecting MODE to GND or
1/3V
MODE to 2/3V
format. An external resistor divider can be used to set the
1/3V
states for the MODE pin.
Table 1. MODE Pin Function
MODE Pin
0
1/3V
2/3V
V
DD
DD
DD
DD
DD
selects straight binary output format. Connecting
or 2/3V
DD
voltages will also help reduce interference
DD
DD
2’s Complement
2’s Complement
Output Format
Straight Binary
Straight Binary
or V
logic values. Table 1 shows the logic
U
DD
selects 2’s complement output
U
LATCH
LTC2298/LTC2297/LTC2296
FROM
W
DATA
Cycle Stabilizer
OE
Clock Duty
Off
Off
PREDRIVER
On
On
LOGIC
V
Figure 12. Digital Output Buffer
DD
U
Overflow Bit
When OF outputs a logic high the converter is either
overranged or underranged.
Output Driver Power
Separate output power and ground pins allow the output
drivers to be isolated from the analog circuitry. The power
supply for the digital output buffers, OV
to the same power supply as for the logic being driven. For
example, if the converter is driving a DSP powered by a 1.8V
supply, then OV
OV
3.6V. OGND can be powered with any voltage from GND up
to 1V and must be less than OV
swing between OGND and OV
Output Enable
The outputs may be disabled with the output enable pin, OE.
OE high disables all data outputs including OF. The data ac-
cess and bus relinquish times are too slow to allow the
outputs to be enabled and disabled during full speed op-
eration. The output Hi-Z state is intended for use during long
periods of inactivity. Channels A and B have independent
output enable pins (OEA, OEB).
V
DD
LTC2298/LTC2297/LTC2296
DD
can be powered with any voltage from 500mV up to
OV
DD
DD
43Ω
229876 F12
should be tied to that same 1.8V supply.
OV
OGND
DD
TYPICAL
DATA
OUTPUT
0.5V
TO V
0.1µF
DD
DD
DD
.
. The logic outputs will
DD
, should be tied
21
229876f