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參數資料
| 型號： | LTC2246HLU#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | ADC |
| 英文描述： | 1-CH 14-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQFP32 |
| 封裝： | 5 X 5 MM, LEAD FREE, PLASTIC, MS-026, TQFP-32 |
| 文件頁數： | 5/16頁 |
| 文件大?。?/td> | 273K |
| 代理商： | LTC2246HLU#TRPBF |
LTC2246H
13
2246hf
Driving the Clock Input
The CLK input can be driven directly with a CMOS or TTL
level signal. A differential clock can also be used along
with a low-jitter CMOS converter before the CLK pin (see
Figure 8).
The noise performance of the LTC2246H can depend on the
clock signal quality as much as on the analog input. Any
noise present on the clock signal will result in additional
aperture jitter that will be RMS summed with the inherent
ADC aperture jitter.
Maximum and Minimum Conversion Rates
The maximum conversion rate for the LTC2246H is 25Msps.
For the ADC to operate properly, the CLK signal should
have a 50% (±5%) duty cycle. Each half cycle must have at
least 18.9ns for the ADC internal circuitry to have enough
settling time for proper operation.
An optional clock duty cycle stabilizer circuit can be used
if the input clock has a non 50% duty cycle. This circuit
uses the rising edge of the CLK pin to sample the analog
input. The falling edge of CLK is ignored and the internal
falling edge is generated by a phase-locked loop. The
input clock duty cycle can vary and the clock duty cycle
stabilizer will maintain a constant 50% internal duty cycle.
If the clock is turned off for a long period of time, the duty
cycle stabilizer circuit will require a hundred clock cycles
for the PLL to lock onto the input clock. To use the clock
duty cycle stabilizer, the MODE pin should be connected
to 1/3VDD or 2/3VDD using external resistors.
If the clock duty cycle stabilizer is used, a >1μs high pulse
should be applied to the SHDN pin once the power supplies
are stable at power up.
The lower limit of the LTC2246H sample rate is determined
by droop of the sample-and-hold circuits. The pipelined
architecture of this ADC relies on storing analog signals on
small valued capacitors. Junction leakage will discharge
the capacitors. The specied minimum operating frequency
for the LTC2246H is 1Msps.
DIGITAL OUTPUTS
Table 1 shows the relationship between the analog input
voltage, the digital data bits, and the overow bit.
Digital Output Buffers
Figure 9 shows an equivalent circuit for a single output
buffer. Each buffer is powered by OVDD and OGND, isolated
from the ADC power and ground. The additional
N-channel transistor in the output driver allows operation
down to low voltages. The internal resistor in series with
the output makes the output appear as 50Ω to external
circuitry and may eliminate the need for external damping
resistors.
As with all high speed/high resolution converters, the
digital output loading can affect the performance. The
digital outputs of the LTC2246H should drive a minimal
capacitive load to avoid possible interaction 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 OVDD voltages will also help reduce interference
from the digital outputs.
APPLICATIONS INFORMATION
Table 1. Output Codes vs Input Voltage
AIN+ – AIN–
(2V Range)
OF
D13 – D0
(Offset Binary)
D13 – D0
(2’s Complement)
>+1.000000V
+0.999878V
+0.999756V
1
0
11 1111 1111 1111
11 1111 1111 1110
01 1111 1111 1111
01 1111 1111 1110
+0.000122V
0.000000V
–0.000122V
–0.000244V
0
10 0000 0000 0001
10 0000 0000 0000
01 1111 1111 1111
01 1111 1111 1110
00 0000 0000 0001
00 0000 0000 0000
11 1111 1111 1111
11 1111 1111 1110
–0.999878V
–1.000000V
<–1.000000V
0
1
00 0000 0000 0001
00 0000 0000 0000
10 0000 0000 0001
10 0000 0000 0000
LTC2246H
2246 F09
OVDD
VDD
0.1μF
43Ω
TYPICAL
DATA
OUTPUT
OGND
OVDD
0.5V
TO 3.6V
PREDRIVER
LOGIC
DATA
FROM
LATCH
OE
Figure 9. Digital Output Buffer
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| LTC2246HLX | 制造商:LINER 制造商全稱:Linear Technology 功能描述:14-Bit, 25Msps 125°C ADC In LQFP |
| LTC2246HLX#PBF | 功能描述:IC ADC 14BIT 25MSPS 48-LQFP RoHS:是 類別:集成電路 (IC) >> 數據采集 - 模數轉換器 系列:- 標準包裝:1 系列:- 位數:14 采樣率（每秒）:83k 數據接口:串行，并聯 轉換器數目:1 功率耗散（最大）:95mW 電壓電源:雙 ± 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:28-DIP（0.600"，15.24mm） 供應商設備封裝:28-PDIP 包裝:管件 輸入數目和類型:1 個單端，雙極 |
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| LTC2246HLX-TRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:14-Bit, 25Msps 125°C ADC In LQFP |
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