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| 型号： | AD8556ARZ-REEL7 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 15/28页 |
| 文件大小： | 0K |
| 描述： | IC AMP CHOPPER 2MHZ 10MA 8SOIC |
| 标准包装： | 1,000 |
| 系列： | DigiTrim® |
| 放大器类型： | 断路器（零漂移） |
| 电路数： | 1 |
| 转换速率： | 1.2 V/µs |
| 增益带宽积： | 2MHz |
| 电流 - 输入偏压： | 49nA |
| 电压 - 输入偏移： | 2µV |
| 电流 - 电源： | 2mA |
| 电流 - 输出 / 通道： | 10mA |
| 电压 - 电源，单路/双路(±)： | 4.5 V ~ 5.5 V |
| 工作温度： | -40°C ~ 140°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SO |
| 包装： | 带卷 (TR) |
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AD8556
Rev. A | Page 22 of 28
Read Mode
The values stored by the polysilicon fuses can be sent to the
FILT/DIGOUT pin to verify correct programming. Normally,
the FILT/DIGOUT pin is only connected to the second gain stage
output via RF. During read mode, however, the FILT/DIGOUT pin
is also connected to the output of a shift register to allow the
polysilicon fuse contents to be read. Because VOUT is a buffered
version of FILT/DIGOUT, VOUT also outputs a digital signal
during read mode.
Read mode is entered by setting Field 1 to 11 and selecting the
desired parameter in Field 2. Field 4 is ignored. The parameter
value, stored in the polysilicon fuses, is loaded into an internal
shift register, and the MSB of the shift register is connected to
the FILT/DIGOUT pin. Pulses at DIGIN shift out the shift
register contents to the FILT/DIGOUT pin, allowing the 8bit
parameter value to be read after seven additional pulses; shifting
occurs on the falling edge of DIGIN. An eighth pulse at DIGIN
disconnects FILT/DIGOUT from the shift register and terminates
the read mode. If a parameter value is less than eight bits long,
the MSBs of the shift register are padded with 0s.
For example, to read the second stage gain, this code is used:
1000 0000 0001 11 00 10 0000 0000 0111 1111 1110. Because
the second stage gain parameter value is only three bits long,
the FILT/DIGOUT pin has a value of 0 when this code is
entered, and remains 0 during four additional pulses at DIGIN.
The fifth, sixth, and seventh pulses at DIGIN return the 3-bit
value at FILT/DIGOUT, the seventh pulse returns the LSB. An
eighth pulse at DIGIN terminates the read mode.
Sense Current
A sense current is sent across each polysilicon fuse to determine
whether it has been blown. When the voltage across the fuse is
less than approximately 1.5 V, the fuse is considered not blown,
and Logic 0 is output from the OTP cell. When the voltage across
the fuse is greater than approximately 1.5 V, the fuse is considered
blown, and Logic 1 is output.
When the AD8556 is manufactured, all fuses have a low
resistance. When a sense current is sent through the fuse, a
voltage less than 0.1 V is developed across the fuse, which is
much lower than 1.5 V; therefore, Logic 0 is output from the
OTP cell. When a fuse is electrically blown, it should have a
very high resistance. When the sense current is applied to the
blown fuse, the voltage across the fuse should be larger than
1.5 V; therefore, Logic 1 is output from the OTP cell.
It is theoretically possible, though very unlikely, for a fuse
to be incompletely blown during programming, assuming the
required conditions are met. In this situation, the fuse could
have a medium resistance, neither low nor high, and a voltage
of approximately 1.5 V could be developed across the fuse.
Therefore, the OTP cell could output Logic 0 or Logic 1, depending
on temperature, supply voltage, and other variables.
To detect this undesirable situation, the sense current can be
lowered by a factor of 4 using a specific code. The voltage
developed across the fuse would then change from 1.5 V to
0.38 V, and the output of the OTP would be Logic 0 instead of
the expected Logic 1 from a blown fuse. Fuses blown correctly
would still output Logic 1. In this way, fuses blown incorrectly
can be detected. Another specific code would return the sense
current to the normal (larger) value. The sense current cannot
be permanently programmed to the low value. When the AD8556
is powered up, the sense current defaults to the high value.
The low sense current code is:
1000 0000 0001 00 00 10 XXXX XXX1 0111 1111 1110.
The normal (high) sense current code is:
1000 0000 0001 00 00 10 XXXX XXX0 0111 1111 1110.
Programming Procedure
For reliable fuse programming, it is imperative to follow the
programming procedure requirements, especially the proper
supply voltage during programming.
1.
When programming the AD8556, the temperature of the
device must be between 10°C and 40°C.
2.
Set VDD and VSS to the desired values in the application.
Use simulation mode to test and determine the desired
codes for the second stage gain, first stage gain, and output
offset. The nominal values for these parameters are shown
codes corresponding to these values as a starting point.
However, because actual parameter values for given codes
vary from device to device, some fine tuning is necessary
for the best possible accuracy.
One way to choose these values is to set the output offset
to an approximate value, such as Code 128 for midsupply,
to allow the required gain to be determined. Then set the
second stage gain so the minimum first stage gain (Code 0)
gives a lower gain than required, and the maximum first
stage gain (Code 127) gives a higher gain than required.
After choosing the second stage gain, the first stage gain
can be chosen to fine tune the total gain. Finally, the output
offset can be adjusted to give the desired value. After
determining the desired codes for second stage gain,
first stage gain, and output offset, the device is ready for
permanent programming.
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相关代理商/技术参数 |
参数描述 |
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| AD8556CP-EBZ | 功能描述:AD8556 DigiTrim? Series 1 - Single Channels per IC Chopper (Zero-Drift) Amplifier Evaluation Board 制造商:analog devices inc. 系列:DigiTrim? 零件状态:有效 每 IC 通道数:1 - 单 放大器类型:断路器（零漂移） 输出类型:单端 压摆率:1.2 V/μs -3db 带宽:- 电流 - 输出/通道:10mA 工作温度:-40°C ~ 140°C 电流 - 电源（主 IC）:2mA 电压 - 电源，单/双（±）:4.5 V ~ 5.5 V 板类型:完全填充 所含物品:板 使用的 IC/零件:AD8556 标准包装:1 |
| AD8556-EVALZ | 制造商:Analog Devices 功能描述:EVALUATION BOARD - Boxed Product (Development Kits) |
| AD8557 | 制造商:AD 制造商全称:Analog Devices 功能描述:Wide Supply Range, Micropower, |
| AD85571 | 制造商:AD 制造商全称:Analog Devices 功能描述:10 MHz, 20 V/レs, G = 1, 10, 100, 1000 i CMOS㈢ Programmable Gain Instrumentation Amplifier |
| AD8557ACPZ-R2 | 功能描述:IC AMP CHOPPER 2MHZ 55MA 16LFCSP RoHS:是 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:DigiTrim® 标准包装:50 系列:- 放大器类型:J-FET 电路数:2 输出类型:- 转换速率:13 V/µs 增益带宽积:3MHz -3db带宽:- 电流 - 输入偏压:65pA 电压 - 输入偏移:3000µV 电流 - 电源:1.4mA 电流 - 输出 / 通道:- 电压 - 电源，单路/双路(±):7 V ~ 36 V，±3.5 V ~ 18 V 工作温度:-40°C ~ 85°C 安装类型:通孔 封装/外壳:8-DIP（0.300"，7.62mm） 供应商设备封装:8-PDIP 包装:管件 |
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