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参数资料
| 型号： | MAX1297ACEG |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | ADC |
| 英文描述： | 265ksps, +3V, 6-/2-Channel, 12-Bit ADCs with +2.5V Reference and Parallel Interface |
| 中文描述： | 2-CH 12-BIT SUCCESSIVE APPROXIMATION ADC, PARALLEL ACCESS, PDSO24 |
| 封装： | 0.150 INCH, QSOP-28 |
| 文件页数： | 14/20页 |
| 文件大小： | 228K |
| 代理商： | MAX1297ACEG |
M
265ksps, +3V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface
14
______________________________________________________________________________________
the chip-select signal, which enables a μP to address
the MAX1295/MAX1297 as an I/O port. When high,
CS
disables the CLK,
WR
, and
RD
inputs and forces the
interface into a high-impedance (high-Z) state.
Input Format
The control bit sequence is latched into the device on
pins D7–D0 during a write command. Table 4 shows
the control-byte format.
Output Data Format
The 12-bit-wide output format for both the MAX1295/
MAX1297 is binary in unipolar mode and two’s comple-
ment in bipolar mode.
CS
,
RD
,
WR
,
INT
, and the 12 bits
of output data can interface directly to a 16-bit data bus.
When reading the output data,
CS
and
RD
must be low.
__________Applications Information
Power-On Reset
When power is first applied, internal power-on reset cir-
cuitry activates the MAX1295/MAX1297 in external clock
mode and sets
INT
high. After the power supplies stabi-
lize, the internal reset time is 10μs; no conversions
should be attempted during this phase. When using the
internal reference, 500μs is required for V
REF
to stabilize.
Internal and External Reference
The MAX1295/MAX1297 can be used with an internal
or external reference voltage. An external reference
can be connected directly to REF or REFADJ.
An internal buffer is designed to provide +2.5V at REF for
both the MAX1295 and MAX1297. The internally trimmed
+1.22V reference is buffered with a +2.05V/V gain.
Internal Reference
The full-scale range with the internal reference is +2.5V
with unipolar inputs and ±1.25V with bipolar inputs. The
internal reference buffer allows for small adjustments
(±100mV) in the reference voltage (Figure 7).
Note:
The reference buffer must be compensated with
an external capacitor (4.7μF min) connected between
REF and GND to reduce reference noise and switching
spikes from the ADC. To further minimize noise on the
reference, connect a 0.01μF capacitor between REFADJ
and GND.
External Reference
With both the MAX1295 and MAX1297, an external refer-
ence can be placed at either the input (REFADJ) or the
output (REF) of the internal reference buffer amplifier.
Using the REFADJ input makes buffering the external
reference unnecessary. The REFADJ input impedance
is typically 17k
.
When applying an external reference to REF, disable
the internal reference buffer by connecting REFADJ to
V
DD
. The DC input resistance at REF is 25k
.
Therefore, an external reference at REF must deliver up
to 200μA DC load current during a conversion and
have an output impedance less than 10
. If the refer-
ence has higher output impedance or is noisy, bypass
it close to the REF pin with a 4.7μF capacitor.
Power-Down Modes
To save power, place the converter in a low-current
shutdown state between conversions. Select standby
mode or shutdown mode through bits D6 and D7 of the
control byte (Tables 1, 4). In both software power-down
modes the parallel interface remains active, but the
ADC does not convert.
Standby Mode
While in standby mode, the supply current is typically
850μA. The part will power up on the next rising edge
of
WR
and be ready to perform conversions. This quick
turn-on time allows the user to realize significantly
reduced power consumption for conversion rates
below 265ksps.
D6
D4
D5
PD0
SGL/
DIF
ACQMOD
A2
A0
A1
D2
D0
(LSB)
UNI
/BIP
PD1
D1
D3
D7
(MSB)
Table 4. Control-Byte Format
V
DD
= +3V
330k
50k
GND
GND
50k
0.01
μ
F
4.7
μ
F
REFADJ
REF
MAX1295
MAX1297
Figure 7. Reference Adjustment with External Potentiometer
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相关代理商/技术参数 |
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|---|---|
| MAX1297ACEG+ | 功能描述:模数转换器 - ADC 12-Bit 2Ch 265ksps 3.6V Precision ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX1297ACEG+T | 功能描述:模数转换器 - ADC 12-Bit 2Ch 265ksps 3.6V Precision ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX1297ACEG-T | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX1297AEEG | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX1297AEEG+ | 功能描述:模数转换器 - ADC 12-Bit 2Ch 265ksps 3.6V Precision ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
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