LTC1744IFW#TR Linear Technology, LTC1744IFW#TR Datasheet - Page 15

• Manufacturer Part Number: LTC1744IFW#TR
• Description: IC ADC 14BIT 50MSPS 48-TSSOP
• Manufacturer: Linear Technology

Specifications of LTC1744IFW#TR

• Number Of Bits: 14
• Sampling Rate (per Second): 50M
• Data Interface: Parallel
• Number Of Converters: 1
• Power Dissipation (max): 1.5W
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-TFSOP (0.240", 6.10mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: LTC1744IFWTR

APPLICATIO S I FOR ATIO
An external bypass capacitor of 4.7 F or larger is required
for the 2.5V reference output, V
frequency low impedance path to ground for internal and
external circuitry. This is also the compensation capacitor
for the reference. It will not be stable without this capacitor.
The difference amplifier generates the high and low refer-
ence for the ADC. High speed switching circuits are
connected to these outputs and they must be externally
bypassed. Each output has two pins: REFHA and REFHB
for the high reference and REFLA and REFLB for the low
reference. The doubled output pins are needed to reduce
package inductance. Bypass capacitors must be con-
nected as shown in Figure 5.
TIE TO V
TIE TO GND FOR 2V RANGE;
RANGE = 2 • V
Figure 6a. 2.2V Range ADC
DD
1V < V
U
14k
11k
FOR 3.2V RANGE;
2.5V
1.1V
SENSE
SENSE
U
SENSE
< 1.6V
4.7 F
1 F
2.5V
V
FOR
1 F
1 F
CM
CM
LTC1744
. This provides a high
W
4.7 F
1744 F06a
0.1 F
4.7 F
0.1 F
SENSE
REFHA
REFHB
REFLB
REFLA
V
CM
Figure 5. Equivalent Reference Circuit
LTC1744
CONTROL
4
DETECT
RANGE
U
AND
2.5V BANDGAP
DIFF AMP
REFERENCE
INTERNAL ADC
HIGH REFERENCE
INTERNAL ADC
LOW REFERENCE
1.6V
Other voltage ranges in between the pin selectable ranges
can be programmed with two external resistors as shown
in Figure 6a. An external reference can be used by applying
its output directly or through a resistor divider to SENSE.
It is not recommended to drive the SENSE pin with a logic
device since the logic threshold is close to ground and
V
the converter as possible. If the SENSE pin is driven
externally, it should be bypassed to ground as close to the
device as possible with a 1 F ceramic capacitor.
DD
BUFFER
1V
. The SENSE pin should be tied high or low as close to
Figure 6b. 2.5V Range ADC with an External Reference
5V
0.1 F
1744 F05
4
LT1790-1.25
1, 2
6
2.5V
1.25V
SENSE
4.7 F
1 F
V
CM
LTC1744
LTC1744
1744 F06b
15
1744f