STA020D. 96kHz DIGITAL AUDIO INTERFACE TRANSMITTER

Transcription

1 khz DIGITAL ADIO INTERFAE TRANSMITTER MONOLITHI DIGITAL ADIO INTERFAE TRANSMITTER 3.3 SPPLY OLTAGE SPPORTS: - AES/EB, IE 5, - S/PDIF, & EIAJ P Professional and onsumer Formats PARITY BITS AND R ODES GENERATED TRANSPARENT MODE ALLOWS DIRET ONNETION OF AND STA1 BLOK DIAGRAM SO24 ORDERING NMBER: DESRIPTION The is a monolithic MOS device which encodes and transmits audio data according to the AES/EB, IE 5, S/PDIF, & EIAJ P-340 interface standards. It supports khz sample rate operation The accepts audio and digital data which is then multiplexed, encoded and driven onto a cable. The audio serial port is double buffered and capable of supporting a wide variety of formats. The multiplexes the channel, user, and validity data directly from serial input pins with dedicated input pins for the most important channel status bits. M0 M1 M2 D+ GND MK RST ADIO SERIAL PORT 10 REGISTERS MX DIFFERENTIAL DEDIATED HANNEL STATS BS BL TRNPT DA5A October 02 1/

2 ABSOLTE MAXIMM RATINGS Symbol Parameter alue nit D+ D Power Supply 4 IND Digital Input oltage -0.3 to D+ 0.3 T amb Ambient Operating Temperature (power applied) - to +5 T stg Storage Temperature -40 to 150 REOMMNDED OPERATING ONDITIONS (GND = 0; all voltages with respect to ground) Symbol Parameter Test ondition Min. Typ. Max. nit D+ D oltage T amb Ambient Operating Temp PIN ONNETION / TRNPT/F1 PRO 2 23 M0 1/F M1 / M2 MK 5 1 D+ 1 GND 1 RST /SBF BL/SB 14 EM0/ / EM1/ DA0A PINS DESRIPTION N. Name Function Power Supply onnections 1 GND Ground. 1 D+ Positive Digital Power. Nominally Audio Input Interface Serial lock. Serial clock for pin which can be configured (via the M0, M1 and M2 pins) as an input or output and can sample data on the rising or falling edge.as an output, will contain 32 clocks for every audio sample. Frame Sync. Delineates the serial data and may indicate the particular channel, left or right and may be an input or output. The format is based on M0, M1 and M2 pins. 2/

3 PINS DESRIPTION (continued) N. Name Function Serial Data. Audio data serial input pin. 21, 22,23 M0, M1, M2 Serial Port Mode Select. Selects the format of and the sample edge of with respect to. ontrol Pins 1 /3 hannel Status Bit /hannel Status Bit 3. In professional mode, is the inverse of channel status bit. In consumer mode, 3 is the inverse of channel status bit 3, /3 are ignored in Transparent Mode. 2 PRO Professional/onsumer Select. Selects between professional mode (PRO low) and consumer mode (PRO high). This pin defines the functionality of the channel status parallel pins. PRO is ignored in Transparent Mode. 3 1/F0 hannel Status Bit 1/Frequency ontrol 0. In professional mode, 1 is the inverse of channel status bit 1. In consumer mode, F0 and F1 are encoded versions of channel status bits 24 and 25 (bits 0 and 1 of byte 3). When F0 and F1 are both high, D mode is selected. 1/F0 are ignored in Transparent Mode. 4 /2 hannel Status Bit /hannel Status Bit 2. In professional mode, is the inverse of channel status bit. In consumer mode, 2 is the inverse of channel status bit 2. /2 are ignored in Transparent Mode. alidity. alidity bit serial input port. This bit is defined as per the digital audio standards wherein = 0 signifies the audio signal is suitable for conversion to analog. = 1 signifies the audio signal is not suitable for conversion to analog, i.e. invalid. 10 /SBF hannel Status Serial Input/Subcode Frame lock. In professional and consumer modes this pin is the channel status serial input port. In D mode this pin inputs the D subcode frame clock. ser Bit. ser bit serial input port. 12 /15 hannel Status Bit /hannel Status Bit 15. In professional mode, is the inverse of channel status bit (bit 1 of byte 1). In consumer mode, 15 is the inverse of channel status bit 15 (bit of byte 1). /15 are ignored in Transparent Mode. 13 EM1/ Emphasis 1/hannel Status Bit. In professional mode, EM0 and EM1 encode channel status bits 2, 3 and 4. In consumer mode, is the inverse of channel status bit (bit 0 of byte 1). EM1/ are ignored in Transparent Mode. 14 EM0/ Emphasis 0/hannel Status Bit. In professional mode, EM0 and EM1 encode channel status bits 2, 3 and 4. In consumer mode, is the inverse of channel status bit (bit 1 of byte 1). EM0/ are ignored in Transparent Mode. 15 BL/SB hannel Status Block Output/Subcode Bit lock. In professional and consumer modes, the channel status block output is high for the first 15 bytes of channel status. In D mode, this pin outputs the subcode bit clock. RST Master Reset. When low, all internal counters are reset. 24 TRNPT/F1 Transparent Mode/Frequency ontrol 1. In professional mode, setting TRNPT low selects normal operation & BL is an output. Setting TRNPT high, allows the to be connected directly to an STA1. In transparent mode, BL is an input & MK must be at 25 Fs. In consumer mode, F0 and F1 are encoded versions of channel status bits 24 and 25. When F0 and F1 are both high, D mode is selected. Transmitter Interface 5 MK Master lock. lock input at 12x the sample frequency which defines the transmit timing. In trasparent mode MK must be 25 Fs., 1, Differential Line Drivers. 3/

4 DIGITAL HARATERISTIS (Tamb = 25 ; D+ = 3.3 ±10%) Symbol Parameter Test ondition Min. Typ. Max. nit IH High-Level Input oltage 2.0 DD +0.3 IL Low-Level Input oltage OH High-Level Output oltage I O = 0µA DD -1.0 OL Low-Level Output oltage I O = 3.2mA 0.4 I in Input Leakage urrent µa MK Master lock frequency (Note 1) 2 MHz Master lock Duty ycle (high time/cycle time) 40 0 % Note 1: MK must be 12x the input word rate, except in Transparent Mode where MK is 25x the input word rate. Figure 1. Professional & onsumer Modes Typical onnection Diagram. EXTERNAL LOK +3.3 MK D+ 0.1µF ADIO DATA PROESSOR µontroller or NSED HANNEL STATS BITS ONTROL BL RST STA0 DEDIATED.S. BITS GND TRNPT M0 M1 M2 SERIAL PORT MODE SELET TRANSMITTER IRIT DA00A Figure 2. Typical onnection Diagram. EXTERNAL LOK +5 ADIO DATA PROESSOR MK 5 D+ 1 1 GND 0.1µF DEODER SBODE PORT SBF SB STA M0 M1 M2 SERIAL PORT MODE SELET RESET ONTROL HANNEL STATS BITS ONTROL RST DEDIATED.S. BITS 1 TRANSMITTER IRIT DAA 4/

5 GENERAL DESRIPTION The is a monolithic MOS circuit that encodes and transmits audio and digital data according to the AES/EB, IE 5, S/PDIF, and EIAJ P-340 interface standards. The chip accepts audio and control data separately; multiplex and biphase-mark encode the data internally and drive it, directly or through a transformer, to a transmission line. The has dedicated pins for the most important control bits and a serial input port for the, and bits. Line Drivers The differential line drivers for are low skew, low impedance, differential outputs capable of driving 0Ohm transmission lines. (RS422 line driver compatible). They can also be disabled by resetting the device (RST = low). DESRIPTION The accepts to 24-bit audio samples through a serial port configured in one of seven formats; provides several pins dedicated to particular channel status bits and allows all channel status, user and validity bits to be serially input through port pins. This data is multiplexed, the parity bit is generated and the bit stream is biphase-mark encoded and driven through an RS422 line driver. The operates as a professional or consumer interface transmitter selectable by pin 2, PRO. As a professional interface device, the dedicated channel status input pins are defined according to the professional standard, and the R code (.S. byte 23) can be internally generated. As a consumer device, the dedicated channel status input pins are defined according to the consumer standard. A submode provided under the consumer mode is compact disk, D, mode. When transmitting data from a compact disk, the D subcode port can accept D subcode data, extract channel status information from it, and transmit it as user data. The master clock, MK, controls timing for the entire chip and must be 12xFs. As an example, if stereo data is input to the at 44.1kHz, MK input must be 12 times that or 5.44MHz. Audio Serial Port The audio serial port is used to enter audio data and consists of three pins:, and, clocks in, which is double buffered, while delineates the audio samples and may indicate the particular channel, left or right. To support many different interfaces, M2, M1 and M0 select one of seven different formats for the serial port. The coding is shown in Table 3 while the formats are shown in Figure 3. Format 0 and 1 are designed to interface with rystal ADs. Format 2 communicates with Motorola and TI DSPs. Format 3 is reserved. Format 4 is compatible with the I 2 S standard. Formats 5 and make the look similar to existing - and 1-bit DAs and interpolation filters. Format is an MSB-last format and is conducive to serial arithmetic. and are outputs in Format 0 and inputs in all other formats. In Format 2, the rising edge of delineates samples and the falling edge must occur a minimum of one bit period before or after the rising edge. In all formats except 2, contains left/right information requiring both edges of to delineate samples. Formats 5 and require a minimum of - or 1-bit audio words respectively. In all formats other than 5 and, the can accept any word length from to 24 bits by adding leading zeros in format and trailing zeros in the other formats, or by restricting the number of periods between active edges of to the sample word length. must be derived from MK, either through a DSP using the same clock or using counters. If SFYN moves (jitters) with respect to MK by four MK periods, the internal counters and BL may be reset. Table 1. Audio Port Modes M2 M1 M0 Format & Output Left/Right, -24 Bits Word Sync, -24 Bits Reserved Left/Right, I 2 S ompatible LSB Justified, Bits LSB Justified, 1 Bits MSB Last, -24 Bits 5/

6 Figure 3. Audio Serial Port Formats. FORMAT 0: (out) (out) (in) FORMAT 1: (in) MSB LSB MSB LSB MSB (in) (in) FORMAT 2: (in) MSB LSB MSB LSB MSB (in) (in) MSB LSB MSB LSB MSB FORMAT 3: (RESERED) FORMAT 4: (in) (in) (in) FORMAT 5: (in) MSB LSB MSB LSB MSB (in) (in) LSB MSB LSB MSB LSB FORMAT : (in) Bits Bits (in) (in) LSB MSB LSB MSB LSB FORMAT : (in) 1 Bits 1 Bits (in) (in) MSB LSB MSB LSB MSB DA04,, Serial Port The serial input pins for channel status (), user (), and validity () are sampled during the first bit period after the active edge of for all formats except Format 4. Format 4 is sampled during the second bit period (coincident with the MSB). In Figure 3, the arrows on indicate when the,, and bits are sampled. The,, and bits are transmitted with the audio sample entered before edge that sampled it. The bit, as defined in the audio standards, is set to zero to indicate the audio data is suitable for conversion to analog. Therefore, when the audio data is errored, or the data is not audio, the bit should be set high. The channel status serial input pin () is not available in consumer mode when the D subcode port is enabled (F1 = F0 = high). Any channel status data entered through the channel status serial input () is logically OR ed with the data entered through the dedicated pins or internally generated. /

7 RST and BL (TRNPT is low) When RST goes low, the differential line drivers are set to ground. In order to properly synchronize the ST0 to the audio serial port, the transmit timing counters, which include BL, are not enabled after RST goes high until eight and one half periods after reset is exited) of. When is configured as a left/right signal (all defined formats except 2), the counters and BL are not enabled until the right sample is being transmitted). This guarantees that channel A is left and channel B is right as per the digital audio interface specs. As shown in Figure 4, channel block start output (BL), can assist in serially inputting the, and bits as BL goes high one bit period before the first bit of the preamble of the first sub-frame of the channel status block is transmitted. This subframe contains channel status byte 0, bit 0. BL returns low one bit period before the start of the frame that contains bit 0 of channel status byte. BL is not available when the D subcode port is enabled. Figure 4 illustrates timing for stereo data input on the audio port. Notice how BL rises while the right channel data (Right 0) is input, but the previous left channel (Left 0) is being transmitted as the first sub-frame of the channel status block (starting with preamble Z). The,, and input ports only need to be valid for a short period after changes. A sub-frame includes one audio sample while a frame includes a stereo pair. A channel status (.S.) block contains 24 bytes of channel status and 34 audio samples (or 12 stereo pairs, or frames, of samples). Figure 4 shows the ports as having left and right bits (e.g. 0L, 0R). Since the.s. block is defined as 12 bits, or one bit per frame, there are actually 2.S. blocks, one for channel A (left) and one for channel B (right). When inputting stereo audio data, both blocks normally contain the same information, so 0L and 0R from the input port pin are both channel status bit 0 of byte 0, which is defined as professional/consumer. These first two bits from the port, 0L and 0R, are logically OR ed with the inverse PRO, since PRO is a dedicated channel status pin defined as.s. bit 0. Also, if in professional mode, 1,, and are dedicated.s. pins. The inverse of 1 is logically OR ed with channel status input ports bits 1L and 1R. In similar fashion,, and are OR ed with their respective input bits. Also, the bits in 12L and 12R are both channel status block bit 12, which is bit 0 of channel status byte. Figure 4. BL and Transmitter Timing. TRNPT high BL TRNPT low BITS FROM PIN TRNPT high 0L 0R 1L 1R 12R 0L 0R,, TRNPT low 11R 0L 0R 1L 12L 11R 0L BITS OR'ed w/pro pin BITS OR'ed w/1 pin BITS 0 of.s. BLOK BYTE Preamble Y P11R P0L Preamble Z P0R Preamble Y P12R P12L Preamble X Preamble Y bit Preamble Z Aux Data LSB Left 0 - Audio Data MSB P0 SB-FRAME DA0 /

8 Transparent Mode In certain applications it is desirable to receive digital audio data with the STA1 and retransmit it with the. In this case, channel status, user and validity information must pass through unaltered. For studio environments, AES recommends that signal timing synchronization be maintained throughout the studio. Frame synchronization of digital audio signals input to and output from a piece of equipment must be within +/- 5%. The transparent mode of the is selected by setting TRNPT, pin 24, high. In this mode, the BL pin becomes an input, allowing direct connection of the outputs of the STA1 to the inputs of the as shown in Figure 1. The transmitter and receiver are synchronized by the signal. BL specifies the start of a new channel status block boundry, allowing the transmit block structure to be slaved to the block structure of the receiver. In the transparent mode,, and are now transmitted with the current audio sample as shown in Figure 5 (TRNPT high) and the dedicated channel status pins are ignored. When is a word clock (Format 2), BL is sampled when left,, are sampled. When is Left/Right, BL is sampled when left,, are sampled. The channel status block boundry is reset when BL transitions from low to high (based on two successive samples of BL). MK for the is normally expected to be 12 times the sample frequency, in the trasparent mode MK must be 25 Fs. Professional Mode Setting PRO low places the in professional mode as shown in Figure. In professional mode, channel status bit 0 is transmitted as a one and bits 1, 2, 3, 4,, and can be controlled via dedicated pins. The pins are actually the inverse of the identified bit. For example, tying the 1 pin low places a one in channel status bit 1. As shown in the application Note, Overview of AES/EB Digital Audio Interface Data Structures, 1 indicates audio/nonaudio; and determine the sample frequency and allows the encoded channel mode to be stereophonic. EM1 and EM0 determine emphasis and encode 2, 3, 4 as shown in Table 2. The dedicated channel status pins are read at the appropriate time and are logically OR ed with data input on the channel status port,. In Transparent Mode, these dedicated channel status pins are ignored and channel status bits are input at the pin. onsumer Mode Setting PRO high places the in consumer mode which redefines the pins as shown in Figure. In consumer mode, channel status bit 0 is transmitted as a zero and channel status bits 2, 3,,, 15, 24 and 25 are controlled via dedicated pins. The pins are actually the inverse of the bit so if pin 2 is tied high, channel status bit 2 will be transmitted as a zero. Also, F0 and F1 are encoded versions of channel status bits 24 and 25, which define the sample frequency. When F0 and F1 are both high, the part is placed in a D submode which activates the D subcode port. This submode is described in detail in the next section. Table 3 describes the encoding of 24 and 25 through the F1 and F0 pins. According to AES/EB standards, 2 is copy prohibit/permit. 3 specifies pre-emphasis, and define the category code and 15 identifies the generation status of the transmitted material (i.e. first generation, second generation). Table 2. Emphasis Encoding EM1 EM Table 3. Sample Frequency Encoding F1 F omments kHz kHz kHz kHz, D Mode Figure 5. Transparent Mode Interface. RXP RXN STA1 MK BL DATA PROESSING TRNPT STA0 DA05 + /

9 Figure. Block Diagram - Professional Mode M0 M1 M SERIAL PORT LOGI ADIO AX Bits R BIPHASE MARK ENODER LINE DRIER 1 10 REGISTERS Bits ALIDITY MX TIMING RST PREAMBLE MX PARITY PRO EM0 EM1 1 TRNPT BL MK DA0B Figure. Block Diagram - onsumer Mode M0 M1 M SERIAL PORT LOGI ADIO AX Bits BIPHASE MARK ENODER LINE DRIER 1 10 MX REGISTERS Bits ALIDITY TIMING RST PREAMBLE MX PARITY PRO F0 F BL MK DA0A /

10 DIM. mm inch MIN. TYP. MAX. MIN. TYP. MAX. OTLINE AND MEHANIAL DATA A A A B D E e 1.2 0,050 H h k 0 (min.), (max.) L SO24 h x 45 A2 A 0.10mm.004 Seating Plane B e A1 K L H A1 D E 1 12 SO24 10/

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