データシートサーチシステム |
|
AD2S90AP データシート(PDF) 6 Page - Analog Devices |
|
AD2S90AP データシート(HTML) 6 Page - Analog Devices |
6 / 12 page AD2S90 REV. D –6– ABSOLUTE POSITION OUTPUT SERIAL INTERFACE Absolute angular position is represented by serial binary data and is extracted via a three-wire interface, DATA, CS and SCLK. The DATA output is held in a high impedance state when CS is HI. Upon the application of a Logic LO to the CS pin, the DATA output is enabled and the current angular information is trans- ferred from the counters to the serial interface. Data is retrieved by applying an external clock to the SCLK pin. The maximum data rate of the SCLK is 2 MHz. To ensure secure data retrieval it is important to note that SCLK should not be applied until a minimum period of 600 ns after the application of a Logic LO to CS. Data is then clocked out, MSB first, on successive nega- tive edges of the SCLK; 12 clock edges are required to extract the full 12 bits of data. Subsequent negative edges greater than the defined resolution of the converter will clock zeros from the data output if CS remains in a low state. If a resolution of less than 12 bits is required, the data access can be terminated by releasing CS after the required number of bits have been read. LSB MSB t3 t4 t5 t1 t7 t6 t* t2 *THE MINIMUM ACCESS TIME: USER DEPENDENT CSB SCLK DATA Figure 6. Serial Read Cycle CS can be released a minimum of 100 ns after the last negative edge. If the user is reading data continuously, CS can be reap- plied a minimum of 250 ns after it is released (see Figure 6). The maximum read time is given by: (12-bits read @ 2 MHz) Max RD Time = [600 + (12 × 500) + 600 + 100] = 7.30 µs. INCREMENTAL ENCODER OUTPUTS The incremental encoder emulation outputs A, B and NM are free running and are always valid, providing that valid resolver format input signals are applied to the converter. The AD2S90 emulates a 1024-line encoder. Relating this to converter resolution means one revolution produces 1024 A, B pulses. B leads A for increasing angular rotation (i.e., clockwise direction). The addition of the DIR output negates the need for external A and B direction decode logic. DIR is HI for increas- ing angular rotation. The north marker pulse is generated as the absolute angular position passes through zero. The AD2S90 supports the three industry standard widths controlled using the NMC pin. Figure 7 details the relationship between A, B and NM. The width of NM is defined relative to the A cycle. A B 90 180 *NM NUMBER OF DEGREES REFERS TO WIDTH RELATIVE TO "A" CYCLE 360 SELECTABLE WITH THREE - LEVEL CONTROL PIN "MARKER" DEFAULT TO 90 USING INTERNAL PULL - UP. * WIDTH LEVEL 90 180 360 +VDD 0 –VSS INCREASING ANGLE Figure 7. A, B and NM Timing Unlike incremental encoders, the AD2S90 encoder output is not subject to error specifications such as cycle error, eccentric- ity, pulse and state width errors, count density and phase φ. The maximum speed rating, n, of an encoder is calculated from its maximum switching frequency, fMAX, and its ppr (pulses per revolution). n = 60 × f MAX PPR The AD2S90 A, B pulses are initiated from CLKOUT which has a maximum frequency of 2.048 MHz. The equivalent encoder switching frequency is: 1/4 × 2.048 MHz = 512 kHz (4 updates = 1 pulse) At 12 bits the ppr = 1024, therefore the maximum speed, n, of the AD2S90 is: n rpm = × = 60 512000 1024 30000 This compares favorably with encoder specifications where fMAX is specified from 20 kHz (photo diodes) to 125 kHz (laser based) depending on the light system used. A 1024 line laser-based encoder will have a maximum speed of 7300 rpm. The inclusion of A, B outputs allows the AD2S90 + resolver solution to replace optical encoders directly without the need to change or upgrade existing application software. |
同様の部品番号 - AD2S90AP |
|
同様の説明 - AD2S90AP |
|
|
リンク URL |
プライバシーポリシー |
ALLDATASHEET.JP |
ALLDATASHEETはお客様のビジネスに役立ちますか? [ DONATE ] |
Alldatasheetは | 広告 | お問い合わせ | プライバシーポリシー | リンク交換 | メーカーリスト All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |