LTC2264UJ-14(RevB) データシートの表示（PDF） - Linear Technology

部品番号

コンポーネント説明

メーカー

LTC2264UJ-14
(Rev.:RevB)

14-Bit, 65Msps/40Msps/25Msps Low Power Dual ADCs

Linear Technology 

LTC2265-14/

LTC2264-14/LTC2263-14

APPLICATIONS INFORMATION

Reference

The LTC2265-14/LTC2264-14/LTC2263-14 has an internal

1.25V voltage reference. For a 2V input range using the

internal reference, connect SENSE to VDD. For a 1V input

range using the internal reference, connect SENSE to

ground. For a 2V input range with an external reference,

apply a 1.25V reference voltage to SENSE (Figure 9).

The input range can be adjusted by applying a voltage to

SENSE that is between 0.625V and 1.30V. The input range

will then be 1.6 • VSENSE.

The reference is shared by both ADC channels, so it is

not possible to independently adjust the input range of

individual channels.

The VREF, REFH and REFL pins should be bypassed, as

shown in Figure 8. The 0.1µF capacitor between REFH and

REFL should be as close to the pins as possible (not on

the backside of the circuit board).

1.25V

LTC2265-14

VREF

1µF

5Ω

1.25V BANDGAP

REFERENCE

0.625V

TIE TO VDD FOR 2V RANGE;

TIE TO GND FOR 1V RANGE;

RANGE = 1.6 • VSENSE FOR

0.625V < VSENSE < 1.300V

SENSE

0.1µF

REFH

RANGE

DETECT

AND

CONTROL

BUFFER

INTERNAL ADC

HIGH REFERENCE

Encode Input

The signal quality of the encode inputs strongly affects

the A/D noise performance. The encode inputs should

be treated as analog signals—do not route them next to

digital traces on the circuit board. There are two modes

of operation for the encode inputs: the differential encode

mode (Figure 10), and the single-ended encode mode

(Figure 11).

1.25V

EXTERNAL

REFERENCE

VREF

1µF

SENSE

LTC2265-14

1µF

226514 F09

Figure 9. Using an External 1.25V Reference

LTC2265-14

VDD

VDD

15k

ENC+

ENC–

30k

DIFFERENTIAL

COMPARATOR

226514 F10

Figure 10. Equivalent Encode Input Circuit

for Differential Encode Mode

2.2µF

0.1µF

0.1µF

0.8x

DIFF AMP

REFL

INTERNAL ADC

LOW REFERENCE

Figure 8. Reference Circuit

226514 F08

LTC2265-14

1.8V TO 3.3V

0V

ENC+

ENC–

30k

CMOS LOGIC

BUFFER

226514 F11

Figure 11. Equivalent Encode Input Circuit

for Single-Ended Encode Mode

20

22654314fb

Share Link: