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Winbond Electronics Corporation America
Single Channel CODEC Mini Evaluation Board W681xxxES User's Guide
Rev 2.0 October 23, 2003
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Description
The W681xxxR-ES has the bare minimum for a digital telephone handset application which will allow the designers to easily connect this small footprint daughter board to their applications. The evaluation system targets developers of such systems as VoIP, Digital Telephony, mobile devices (wireless headsets), PBX that would like to test and or develop with Winbond Family of Voice CODECs into a new system with minimal or no additional analog design at all ("Plug & Play"). 2 Features Smallest form that contain the bare minimum components to allow a handset/headset application. It allows system developers to bypass the analog in and analog out components with a simplified procedure. * * * * 3 Prototype area for developer to hook up the side-tone resistor on board or RJ9 (hand-set jack) or headset jack. The board has the resistors that will allow the maximum amplification for a 32 Ohm speaker and a standard microphone All CODEC pins lead to holes that enable the developer to solder wires to connect to his system board. The board is designed to minimize any outside noises for the cleanest signals possible.
Hardware
3.1 Power supply requirements
3V or 5V depending on the selected CODEC.
Winbond Codec Part Number Operating Voltage W6810ES W681512ES W681310 ES 5V 5V 3V
Table 3.1: Power Supply ( The User needs to connect VCC and GND Pins )
VCC GND
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3.2 Schematics
R10 1K C1 0.1uF C7 1200pf J23 0.1uF 1 2 3 4 C3 R3 1K R5 27K U1 AO 17 18 C8 R6 R7 20K R8 3K 1200pf 27K 19 VAG 20 VREF 1 ROPAI 2 3 AO AIAI+ VAG VREF ROPAI PAOPAO+ VSS u/A PUI 16 10 U/A PUI (PCM MODE CONTROL) (POWER CONTROL) 6 VCC VCC
R1 1.5K C2
+
C4 4.7uF @10v
R12 2K
MIC+ SPKSPK+ MIC-
VDD
R9 27K R4 1K
FST BCLKT PCMT MCLK PCMR BCLKR FSR
14 12 13 11 8 9 7
FST BCLKT PCMT MCLK PCMR BCLKR FSR
(FRAME SYNC TRANSMIT) (BIT CLOCK TRANSMIT) (PCM OUTPUT) (2.048 MHz MASTER CLOCK IN) (PCM INPUT) (BIT CLOCK RECEIVE) (FRAME SYNC RECEIVE)
CON4
0.1uF VCC J21 1 CON1 1 J22 CON1 C6 0.1uF 0 Ohm R11 R2 1.5K
PAO- 4 PAO+ 5 C5 0.1uF
15 J7
W68XXXX
VREF
1
J1 CON1
FSR
1
PCMT
1
J13 CON1
U/A
1
J16 CON1
AI+
1
J19 CON1
CON1 PCMR 1 J8 CON1 BCLKR J9 1 CON1 PUI 1 J10 CON1 MCLK 1 J11 CON1 BCLKT J12 1 CON1 1 FST 1
RO-
1
J2 CON1
J14 CON1 J15 CON1
AO
1
J17 CON1
VAG
1
J20 CON1
W6810, W681512 or W681310 are Populated with C6 and R11 as shown below. C6
Populated Not Populated Populated
PAI
J3 1 CON1
AI-
J18 1 CON1
R11
Not Populated Not Populated Not Populated
Device Number
PAO-
W6810
1
J4 CON1
W681512
W681310
PAO+ VCC
1
J5 CON1 J6
1 CON1
Figure 1: EW681xxxES Board Schematics Telephone Handset Default Diagram 4 Connecting Microphone and Speaker to the W681xxxES
J23 can be used to connect an RJ9 plug from a "standard" telephone handset or headset to the appropriate pins on the board (Table 4.0). The default resistor and capacitor values on the board are used for the maximum amplification with no saturation of a 32ohm speaker using a standard microphone. Unfortunately the only thing "standard" about the RJ9 handset jack is that the microphone and speaker are always on the same pins. BUT, the microphone polarity can be positive, or negative, depending upon how the manufacturer designed their telephone set. This means that one has about a 50% chance of wiring it up wrong the first time UNLESS you know ahead of time which polarity handset you have. Many years ago, with carbon microphones acting as variable resistors this was not an issue. But with today's modern handsets using polarized electret microphones polarity is very important. The circuit in Figure 1 assumes that the positive side of the microphone is connected to pin 1 of the RJ9 plug and the negative side to pin 4. Reversing the wires from the RJ9 to the holes in J23 will solve the polarity problem if there is no audio. Pin1 Pin2 Pin3 Pin4 Mic+ Speaker- Speaker+ Mic Table 4.0 : J23 Pin assignments
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Note: It is recommended to use short wires to hook up this board to the prototype system for minimal added noise.
4.1 Adjusting the Amplifier levels for optimal performance
In the handset, application the gain from the handset microphone is set to 27 for the input amplifier. This is because the acoustical chamber in the telephone type handset lets the electret microphone provide an output of ~28 mVRMS. The chamber typically has a gain of three over a bare microphone (or one placed with only a small opening to the outside world.) Because of the high sensitivity of the earphone (150 impedance) in a typical handset, the output gain from the Power Amp is set to ~0.16 for a satisfactory listening level. SCHEMATIC COMPONENT # R3,4 R5,6 C7,8 R9 R7 R8 TELEPHONE HANDSET (Values Populated on the board) 1K 27K 1200 pF SELECT 20K 3K VoIP PHONE SET (No acoustic Chamber) 1K 91K 330 pF SELECT 20K 3K 600 LINE IN/OUT (Tip/Ring) 10K 10K N/U N/U 27k 27k
Table 4.1: Suggested Components Values By Application In the VoIP telephone, or small wireless phones, the plastic case is typically too small to provide a reasonable acoustic chamber. Thus the output from the microphone is less than in the previous example. This results in having to set the input gain of the CODEC to ~75 to 90. This results in a comparable signal level to the receive telephone handset but, because of the increased gain, the Signal-to-Noise Ratio (SNR) has decreased and the signal sounds noisier. On the receive side, the gain is set as in the previous example. When the Power Amp gain is as low as 0.16 a 32 ohm load can be driven. If the CODEC is used in a telephone Line Card or a VoIP gateway to the external telephone network then it will usually be set for 0TLP in and out. This means that the input gain and output gain will be 1:1 and the values of resistors will be different again. Note that the output of RO- is at 0TLP and going differential will double this level out of the Power Amp. However, R13 and R14 are 300 ohm resistors to match to the 600 ohm line and the voltage presented to the line will be 0TLP. Resistor R9 sets the side-tone level (the signal fed back to the ear piece from the microphone so the telephone sounds "live") to the level desired by the designer. In most 600 ohm audio line applications, this feature is not needed. R11 is a just a 0 ohm jumper to allow the board to be used with more than one model of CODEC. See the chart. R12 is a pull-up resistor for the PCM Transmit line if there is not one elsewhere in the application.
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VDD C7 330 pF
R10 1K C4 4.7uF
R5 91K
R1 1.5K
C2 0.1uF
R3 1K
AIAO TO FILTERS AND ENCODER
M1
R2 1.5K
C3 0.1uF
R4 1K
AI+
R6 91K C8
FROM FILTER AND DECODER
Figure 2: VoIP Phone Set Diagram
R5 10K
C2 0.1uF LINE IN
R3 10K
AIAO TO FILTERS AND ENCODER
C3 0.1uF
R4 10K
AI+
R6 10K
FROM FILTER AND DECODER
RO-
R7 27K
Figure 3: 600 Ohm Line IN/OUT Diagram
+ VAG 330 pF R9 SELECT SIDETONE LEVEL CONTROL R8 3K LS1 ROR7 20K PAI PAOPAO+ 32 Ohm SPEAKER
+ VAG PAI
R13 R8 27K PAOPAO+ R14
300 OHM to 600 Ohm Line/Load Note: R13 and R14 are not on board 300 OHM LINE OUT
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Ordering information
Table 5.0 describes the various CODEC Evaluation Systems. Evaluation Board part Number W6810ES W681512ES W681310 ES Winbond Codec Part number W6810IR W681512R W681310R
Table 5.0: W681xxxES Part Number
The information contained in this datasheet may be subject to change without notice. It is the responsibility of the customer to check the Winbond USA website (www.winbond-usa.com) periodically for the latest version of this document, and any Errata Sheets that may be generated
Headquarters
Winbond Electronics Corporation America
Winbond Electronics (Shanghai) Ltd.
27F, 299 Yan An W. Rd. Shanghai, 200336 China TEL: 86-21-62365999 FAX: 86-21-62356998
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Taipei Office
Winbond Electronics Corporation Japan
7F Daini-ueno BLDG, 3-7-18 Shinyokohama Kohoku-ku, Yokohama, 222-0033 TEL: 81-45-4781881 FAX: 81-45-4781800
Winbond Electronics (H.K.) Ltd.
Unit 9-15, 22F, Millennium City, No. 378 Kwun Tong Rd., Kowloon, Hong Kong TEL: 852-27513100 FAX: 852-27552064
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Please note that all data and specifications are subject to change without notice. All the trademarks of products and companies mentioned in this datasheet belong to their respective owners.
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