参数资料
| 型号： | 101-0558 |
| 厂商： | Rabbit Semiconductor |
| 文件页数： | 24/94页 |
| 文件大小： | 0K |
| 描述： | COMPUTER SNG BD BL1800 512K SRAM |
| 标准包装： | 10 |
| 系列： | SBC |
| 模块/板类型： | 单板计算机模块 |
| 适用于相关产品： | BL1800 |
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26
Jackrabbit (BL1800)
3.4.2 DA0
The op amp supporting DA0 translates a 12%–88% duty cycle to an analog voltage range
of 0 V to 3 V. The software operates only within this duty cycle; a duty cycle less than
12% is rounded down to 0%, and any duty cycle above 88% is rounded up to 100%.
DA0 uses a voltage divider that consists of R21 and R27 and a gain-offset circuit that con-
sists of R26 and R29 to achieve the output range of 0 V to 3 V within the software duty
cycle.
The DA0 output can be less than 100 mV for a 0% duty cycle and above 3.0 V for a 100%
duty cycle. The duty cycle is programmed as the high-time count of 1024 total counts of
the Rabbit 2000’s timer B. Thus, 256 counts would be 25% of 1024 counts, and corre-
sponds to a 25% duty cycle.
Table 3 lists typical DA0 voltages measured for various duty cycle values with a load
larger than 1 M
.
It is important to remember that the DA0 output voltage will not be realized instantaneously
after programming in a value. There is a settling time because of the RC time constant
(R21 || R27 × C20), which is 7.68 ms. For example, the voltage at any given time is
V = VP – (VP – VDA0)e
(-t/RC)
(EQ 2)
where V is the voltage at time t, VP is the programmed voltage, VDA0 is the last DA0 out-
put voltage from the D/A converter, and RC is the time constant (7.68 ms). The settling
will be within 99.326% (or within about 21 mV for a 3 V change in voltage) after five time
constants, or 38 ms. Six time constants, 46 ms, will allow settling to within 99.75% (or to
within about 8 mV for a 3 V change in voltage). Seven time constants, 54 ms, will allow
settling to within 99.91% (or to within about 3 mV for a 3 V change in voltage).
The settling time is reduced somewhat by precharging capacitor C20 with pulse-width
modulation from PD2.
Table 3. Typical DA0 Voltages for Various Duty Cycles
Duty Cycle
(%)
Voltage
(V)
Programmed Count
0
0.074
0–122
12
0.076
123
25
0.530
256
50
1.467
512
75
2.406
768
88
2.875
901
100
3.345
902–1024
相关PDF资料 |
PDF描述 |
|---|---|
| 396-036-526-204 | CARD EDGE 36POS DL .125X.250 BLK |
| 396-036-526-202 | CARD EDGE 36POS DL .125X.250 BLK |
| 101-0411 | INTERFACE 12KEYDISP ETHNT OP6700 |
| AT24C02A-10PI-2.7 | IC EEPROM 2KBIT 400KHZ 8DIP |
| AT24C02A-10PI-1.8 | IC EEPROM 2KBIT 400KHZ 8DIP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| 10105584 | 制造商:Amphenol Corporation 功能描述:10-341374-222 - Bulk |
| 101055OO | 制造商:TE Connectivity 功能描述: |
| 101056084S | 制造商:Amphenol Aerospace 功能描述:CONNECTOR |
| 101-0561 | 功能描述:模块化系统 - SOM RCM3400 RABBITCORE RoHS:否 制造商:Digi International 外观尺寸:ConnectCore 9P 处理器类型:ARM926EJ-S 频率:150 MHz 存储容量:8 MB, 16 MB 存储类型:NOR Flash, SDRAM 接口类型:I2C, SPI, UART 工作电源电压:3.3 V 最大工作温度:+ 85 C 尺寸:1.97 in x 1.97 in x 6.1 in |
| 10-105610-02S | 制造商:Amphenol Aerospace 功能描述:PLUG |
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