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| 型號： | ADUC814 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | MicroConverter, Small Package 12-Bit ADC with Embedded Flash MCU |
| 中文描述： | MicroConverter的，小包裝12位ADC，嵌入式閃存MCU |
| 文件頁數(shù)： | 26/72頁 |
| 文件大小： | 846K |
| 代理商： | ADUC814 |
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ADuC814
Table 10. Some Single-Supply Op Amps
Op Amp Model
OP281/OP481
OP191/OP291/OP491
OP196/OP296/OP496
OP183/OP283
OP162/OP262/OP462
AD820/OP822/OP824
AD823
Rev. A | Page 26 of 72
Characteristics
Micropower
I/O good up to V
DD
, low cost
I/O to V
DD
, micropower, low cost
High gain-bandwidth product
High GBP, micropackage
FET input, low cost
FET input, high GBP
Keep in mind that the ADC’s transfer function is 0 V to V
REF
,
and any signal range lost to amplifier saturation near ground
impacts dynamic range. Though the op amps in Table 10 are
capable of delivering output signals very closely approaching
ground, no amplifier can deliver signals all the way to ground
when powered by a single supply. Therefore, if a negative supply
is available, one could consider using it to power the front end
amplifiers. If you do, however, be sure to include the Schottky
diodes shown in Figure 26 (or at least the lower of the two
diodes) to protect the analog input from undervoltage conditions.
VOLTAGE REFERENCE CONNECTIONS
The on-chip 2.5 V band gap voltage reference can be used as the
reference source for the ADC and DACs. To ensure the accuracy
of the voltage reference, decouple the V
REF
and the C
REF
pin to
ground with 0.1 μF capacitors as shown in Figure 27.
BUFFER
BUFFER
0.1
μ
F
0.1
μ
F
V
REF
C
REF
2.5V
BAND GAP
REFERENCE
TO ADC
REFERENCE
INPUT
ADuC814
0
Figure 27. Decoupling V
REF
and C
REF
If the internal voltage reference is to be used as a reference for
external circuitry, the C
REF
output should be used. However, a
buffer must be used in this case to ensure that no current is
drawn from the C
REF
pin itself. The voltage on the C
REF
pin is
that of an internal node within the buffer block, and its voltage
is critical to ADC and DAC accuracy. As outlined in the
Reference Input/Output section of the Specifications table, the
internal band gap reference takes typically 80 msecs to power
on and settle to its final value. To ensure accurate ADC operation,
one should wait for the ADC to settle after power-on.
If an external voltage reference is preferred, it should be con-
nected to the V
REF
and C
REF
pins as shown in Figure 28. Bit 6 of
the ADCCON1 SFR must be set to 1 to switch in the external
reference voltage. To ensure accurate ADC operation, the
voltage applied to V
REF
must be between 1.0 V and AV
DD
. In
situations where analog input signals are proportional to the
power supply (such as some strain gage applications) it can be
desirable to connect the V
REF
pin directly to AV
DD
.
BUFFER
C
REF
1 = EXTERNAL
0 = INTERNAL
ADuC814
ADCCON1.6
V
DD
0
2.5V
BAND GAP
REFERENCE
EXTERNAL
VOLTAGE
REFERENCE
TO ADC
REFERENCE
INPUT
0.1
μ
F
0.1
μ
F
V
REF
Figure 28. Using an External Voltage Reference
Operation of the ADC with a reference voltage below 1.0 V,
however, may incur loss of accuracy eventually resulting in
missing codes or non-monotonicity. For that reason, do not use
a reference voltage less than 1.0 V.
CONFIGURING THE ADC
In configuring the ADC a number of parameters need to be set
up. These parameters can be configured using the three SFRs:
ADCCON1, ADCCON2, and ADCCON3, which are detailed in
the following sections.
The ADCCLK determines the speed at which the ADC logic
runs while performing an ADC conversion. All ADC timing
parameters are calculated from the ADCCLK frequency. On the
ADuC814, the ADCCLK is derived from the maximum core
frequency (F
CORE
), 16.777216 MHz. The ADCCLK frequency is
selected via ADCCON1 Bits 5 and 4, which provide four core
clock divide ratios of 8, 4, 16, and 32, generating ADCCLK
values of 2 MHz, 4 MHz, 1 MHz, and 500 kHz, respectively.
The acquisition time (T
ACQ
) is the number of ADCCLKs that
the ADC input circuitry uses to sample the input signal. In most
cases, an acquisition time of one ADCCLK provides more than
adequate time for the ADuC814 to acquire its signal before
switching the internal track-and-hold amplifier into hold mode.
The only exception is a high source impedance analog input,
but this should be buffered first anyway because high source
impedances can cause significant dc errors (see Table 6).
ADCCON1 Bits 3 and 2 are used to select acquisition times of
1, 2, 3, and 4 ADCCLKs.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADUC814_02 | 制造商:AD 制造商全稱:Analog Devices 功能描述:MicroConverter, Small Package 12-Bit ADC with Embedded FLASH MCU |
| ADUC814AN | 功能描述:8052 MicroConverter? ADuC8xx Microcontroller IC 8-Bit 16.78MHz 8KB (8K x 8) FLASH 制造商:analog devices inc. 系列:MicroConverter? ADuC8xx 包裝:- 零件狀態(tài):上次購買時間 核心處理器:8052 核心尺寸:8-位 速度:16.78MHz 連接性:I2C，SPI，UART/USART 外設(shè):POR，PSM，溫度傳感器，WDT I/O 數(shù):- 程序存儲容量:8KB（8K x 8） 程序存儲器類型:閃存 EEPROM 容量:640 x 8 RAM 容量:256 x 8 電壓 - 電源（Vcc/Vdd）:2.7 V ~ 5.5 V 數(shù)據(jù)轉(zhuǎn)換器:* 振蕩器類型:內(nèi)部 工作溫度:* 封裝/外殼:- 供應(yīng)商器件封裝:- 標(biāo)準(zhǔn)包裝:1 |
| ADUC814ARU | 功能描述:IC ADC 12BIT W/FLASH MCU 28TSSOP RoHS:否 類別:集成電路 (IC) >> 嵌入式 - 微控制器， 系列:MicroConverter® ADuC8xx 標(biāo)準(zhǔn)包裝:38 系列:Encore!® XP® 核心處理器:eZ8 芯體尺寸:8-位 速度:5MHz 連通性:IrDA，UART/USART 外圍設(shè)備:欠壓檢測/復(fù)位，LED，POR，PWM，WDT 輸入/輸出數(shù):16 程序存儲器容量:4KB（4K x 8） 程序存儲器類型:閃存 EEPROM 大小:- RAM 容量:1K x 8 電壓 - 電源 (Vcc/Vdd):2.7 V ~ 3.6 V 數(shù)據(jù)轉(zhuǎn)換器:- 振蕩器型:內(nèi)部 工作溫度:-40°C ~ 105°C 封裝/外殼:20-SOIC（0.295"，7.50mm 寬） 包裝:管件 其它名稱:269-4116Z8F0413SH005EG-ND |
| ADUC814ARU-D2 | 制造商:Analog Devices 功能描述:12 BIT ADC WITH EMBEDDED 8-BIT MICRO I.C - Tape and Reel 制造商:Rochester Electronics LLC 功能描述:12 BIT ADC WITH EMBEDDED 8-BIT MICRO I.C - Bulk |
| ADUC814ARU-REEL | 制造商:Analog Devices 功能描述:MCU 8-Bit ADuC8xx 8052 CISC 8KB Flash 3V/5V 28-Pin TSSOP T/R 制造商:Analog Devices 功能描述:12 BIT ADC WITH EMBEDDED 8-BIT MICRO I.C - Tape and Reel |
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