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参数资料
| 型号： | LTC2285IUP#3CGPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | ADC |
| 英文描述： | PROPRIETARY METHOD ADC, PQCC64 |
| 封装： | 9 X 9 MM, LEAD FREE, PLASTIC, QFN-64 |
| 文件页数： | 7/24页 |
| 文件大小： | 578K |
| 代理商： | LTC2285IUP#3CGPBF |
LTC2285IUP#3CGPBF
15
2285iup#3cgpbf
APPLICATIONS INFORMATION
Reference Operation
Figure 9 shows the LTC2285IUP#3CGPBF reference cir-
cuitry consisting of a 1.5V bandgap reference, a difference
amplier and switching and control circuit. The internal
voltage reference can be congured for two pin selectable
input ranges of 2V (
±1V differential) or 1V (±0.5V differ-
ential). Tying the SENSE pin to VDD selects the 2V range;
tying the SENSE pin to VCM selects the 1V range.
The 1.5V bandgap reference serves two functions: its
output provides a DC bias point for setting the common
mode voltage of any external input circuitry; additionally,
the reference is used with a difference amplier to gener-
ate the differential reference levels needed by the internal
ADC circuitry. An external bypass capacitor is required
for the 1.5V reference output, VCM. This provides a high
frequency low impedance path to ground for internal and
external circuitry.
Figure 9. Equivalent Reference Circuit
The difference amplier generates the high and low
reference for the ADC. High speed switching circuits are
connected to these outputs and they must be externally
bypassed. Each output has two pins. The multiple output
pins are needed to reduce package inductance. Bypass
capacitors must be connected as shown in Figure 9. Each
ADC channel has an independent reference with its own
bypass capacitors. The two channels can be used with the
same or different input ranges.
Other voltage ranges between the pin selectable ranges
can be programmed with two external resistors as shown
in Figure 10. An external reference can be used by ap-
plying its output directly or through a resistor divider to
SENSE. It is not recommended to drive the SENSE pin
with a logic device. The SENSE pin should be tied to the
appropriate level as close to 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 1μF
ceramic capacitor. For the best channel matching, connect
an external reference to SENSEA and SENSEB.
Figure 10. 1.5V Range ADC
Input Range
The input range can be set based on the application.
The 2V input range will provide the best signal-to-noise
performance while maintaining excellent SFDR. The 1V
input range will have better SFDR performance, but the
SNR will degrade by 5.7dB. See the Typical Performance
Characteristics section.
Driving the Clock Input
The CLK inputs can be driven directly with a CMOS or
TTL level signal. A sinusoidal clock can also be used
along with a low jitter squaring circuit before the CLK pin
(Figure 11).
VCM
REFH
SENSE
TIE TO VDD FOR 2V RANGE;
TIE TO VCM FOR 1V RANGE;
RANGE = 2 VSENSE FOR
0.5V < VSENSE < 1V
1.5V
REFL
2.2μF
INTERNAL ADC
HIGH REFERENCE
BUFFER
0.1μF
2285 F09
4Ω
DIFF AMP
1μF
INTERNAL ADC
LOW REFERENCE
1.5V BANDGAP
REFERENCE
1V
0.5V
RANGE
DETECT
AND
CONTROL
LTC2285IUP#3CGPBF
VCM
SENSE
1.5V
0.75V
2.2μF
12k
1μF
12k
2285 F10
LTC2285IUP
#3CGPBF
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相关代理商/技术参数 |
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| LTC2285IUPPBF | 制造商:Linear Technology 功能描述:ADC, Dual 14b 125Msps, 3V, LTC2285IUP |
| LTC2285IUP-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual 14-Bit, 125Msps Low Power 3V ADC |
| LTC2285IUP-TR | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual 14-Bit, 125Msps Low Power 3V ADC |
| LTC2285IUP-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual 14-Bit, 125Msps Low Power 3V ADC |
| LTC2285UP | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual 14-Bit, 135Msps Low Power 3.3V ADC |
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