LTC2259-14 查看數據表（PDF） - Linear Technology

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LTC2259-14

14-Bit, 125/105/80Msps Ultralow Power 1.8V ADCs

Linear Technology 

LTC2261-14

LTC2260-14/LTC2259-14

APPLICATIONS INFORMATION

Reference

The LTC2261-14/2260-14/2259-14 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 external 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.

ANALOG

INPUT

HIGH SPEED

DIFFERENTIAL

AMPLIFIER

0.1μF

++

200Ω 200Ω

25Ω

– – 0.1μF

25Ω

VCM

0.1μF

AIN+

LTC2261-14

12pF

AIN–

Figure 7. Front-End Circuit Using a High

Speed Differential Amplifier

226114 F07

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 back side of the circuit board).

1.25V

LTC2261-14

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

0.65V < VSENSE < 1.300V

SENSE

0.1μF

REFH

RANGE

DETECT

AND

CONTROL

BUFFER

INTERNAL ADC

HIGH REFERENCE

2.2μF

0.1μF

0.1μF

0.8x

DIFF AMP

REFL

INTERNAL ADC

LOW REFERENCE

Figure 8. Reference Circuit

226114 F08

1.25V

EXTERNAL

REFERENCE

VREF

1μF

SENSE

LTC2261-14

1μF

226114 F09

Figure 9. Using an External 1.25V Reference

226114f

19

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