PSB7238

Features:

Functions
` G.728 compression/decompression (16 Kbit/s)
` G.723 compression/decompression (6.3, 5.3 Kbit/s)
` G.722 compression/decompression for 7-kHz audio (64, 56, 48 Kbit/s)
` G.711 compression/decompression (64 Kbit/s)
`Outband controlled audio protocol with optimized data rate
`Digital sampling rate conversion (16 kHz - 8 kHz) for G.722 audio with 8-kHz Codec (bandwidth reduced to 3.4 kHz)
` Accepts/outputs uncompressed audio in 8-bit PCM A/m law or 16-bit linear format
` Uncompressed/compressed audio switchable between different interface combinations (IOM/Serial Audio
    Interface, IOM/Host, Host/Host)
` Inband controlled H.221/H.223 oriented audio protocol, e.g. for direct serial connection to videocodec (VCP
    of 8´8 Inc., formerly IIT Inc.) as well as host based solutions
`Stable reaction on interrupt handshake timing violations of e.g. a slow host (Windows® PC)

System On-chip Functions
`Two universal serial HDLC/transparent data controllers
` IOM-2 monitor and C/I channels
` Generation of programmable system clock output
` Three programmable timers
` Programmable on-chip PLL for internal clock generation from ISDN low frequency (7.68 MHz) clock

Interfaces
` 4-line IOM-2/PCM interface
` 5-line serial audio interface, e.g. for connection to videocodec/H.221/223 processor
` Parallel 8-bit Host interface
` 4-line general purpose interface
` External memory interface to external SRAM with programmable waitstates (0 to 15), for development
    purposes only.

Control
`Programmable via parallel host interface
` Operating parameters and mode settings via a register bank
` Access to audio channels and HDLC/serial transparent data controllers from DSP or an external host
` Interface to external software via a full-duplex 256-byte on-chip mailbox
` H.221/H.223 oriented inband configuration/mode switching

General
` Supply voltage: 3.0 - 3.6 V
` Additional 4.5 to 5.5 V supply for connection to 5-V systems without external

components
` Ambient temperature range 0   to + 70
` P-TQFP-100 package



Pinout




Specifications

Parameter	Symbol	Limit Values	Units
Ambient temperature under bias	TA	0 to 70
Storage temperature	Tstg	65 to 125
Supply Voltage	VDD	0.5 to 4.2	V
Supply Voltage	VDDA	0.5to 4.2	V
Supply Voltage	VDDP	0.5to 6.0	V
Voltage of pin with respect to ground: XTAL1, XTAL2,	VS	0.4 to VDDA + 0.5	V
Voltage on any pin with respect to ground	VS	If VDDP < 3 V: 0.4 to VDD + 0.5 If VDDP > 3 V: 0.4 to VDDP + 0.5	V V

ESD-integrity is 500 V.

Note: Stresses above those listed here may cause permanent damage to the device. Exposure to absolute maximum
         rating conditions for extended periods may affect device reliability.


Description

The PSB7238 Joint Audio Decoder Encoder Multimode (JADE MM) is a device which implements voice compression algorithms using the Low-Delay Code Excited Linear Prediction (LD-CELP) standard as defined in the ITU-T G.728 Recommendation, the Algebraic Code Excited Linear Prediction (ACELP) and the Multi-Pulse Maximum Likelihood Quantization (MP-MLQ) standard as defined in the ITU-T G.723 Recommendation, and for 7-kHz voice using the Sub-Band Coded Adaptive Differential PCM (SBC-ADPCM) coding according to the G.722 Recommendation. In addition G.711 PCM audio coding is also supported.

Thus in the G.728 mode PSB7238 compresses a digitized PCM (64 Kbit/s) or linear (128 Kbit/s) voice signal into a 16 Kbit/s bit stream, and vice versa. The algorithm is implemented in 16-bit fixed point arithmetic and complies with the newest fixed point specification set forth by the ITU.

In G.723 mode PSB7238 compresses the PCM or linear voice signal into 5.3 Kbit/s (ACELP) or 6.3 Kbit/s (MP-MLQ) bit stream, and vice versa. The implementation complies with the newest ITU-T C-code V5.1 and includes the G.723 Annex A (Voice Activity Detection and Comfort Noise Generation).

In the G.722 mode PSB7238 compresses the PCM compressed (128 Kbit/s) or the linear uncompressed (256 Kbit/s) 7-kHz audio samples into a rate of 48/56/64 Kbit/s, and vice versa.

The JADE finds applications in PSB7238
   ISDN Videophones (H.320)
  Analog Videophones (H.324)
  Video Conference Systems
  Corporate Network voice concentrators, multiplexers and gateways
  Data-over-voice and Voice-over-data terminals.

Other potential PSB7238 application areas are:
  Networks (e.g. LANs) for packetized voice
  Digital Added Main-Line (DAML) & Digital Circuit Multiplication Equipment (DCME)
  Voice storage e.g. in PC based applications
  Message recording and distribution.

The PSB7238 interfaces of the JADE allow a seamless integration into IOM-2 based systems. After the circuit is set up in the proper mode of operation and parameter settings are programmed by a controlling software, the circuit runs independent of the rest of the system. Status and control information to/from the JADE can be transferred either
inband the compressed audio data via the corresponding selected interface or outband using an 8-bit parallel host interface.

In a Videophone system using the 8´8 (formerly IIT) VCP (Video Codec and Multimedia Communications Processor) the Siemens PSB 7238 can work standalone without the need of external initialization. The default configuration of the JADE is such, that no host is needed in this case and the full communication is done between the VCP and the
Siemens PSB7238.

The voice compression algorithms PSB7238 are implemented by an embedded 16-bit fixed point Digital Signal Processor with all memories internal and no external memory needed. Integration of these and other features, as well as perfectly matched interfaces with other ICs allows for the implementation of highly optimized, low cost system solutions e.g. for
Videophones, Data-over-voice and Channel Multiplexing equipment.

For system integration, two serial HDLC/transparent data channels are implemented which can be serviced by an attached host (or the on-chip DSP). System functions and communication between the chip PSB7238and an external controller is supported by a full-duplex 256-byte on-chip mailbox communication memory.

The circuit PSB7238 is offered in a Quad Flat Pack package with 100 pins (P-TQFP-100: size 14  * 14 mm, pitch 0.5 mm, height 1.4 mm).

Note: This Data Sheet gives a thorough description of the functions and hardware that forms the base of PSB 7238. It includes information (e.g. External Memory Interface) that is not needed for the PSB7238 as a " ready to use plug and play" G.728/G.723/G.722/G.711 audio compression device.