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UCB1300

Advanced modem/audio analog front-end

Product speciﬁcation Supersedes data of 1999 Jul 20

2000 Jun 26

Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end

FEATURES

• 48 pin LQFP (SOT313-2) small body SMD package and low external component count results in minimal PCB space requirement

• 12-bit sigma delta audio codecwith programmable samplerate, input andoutput voltage levels, capable of connecting directly to speaker and microphone, including digitally controlled mute, loopback and clip detection functions

• 14-bit sigma delta telecom codec with programmable sample rate, including digitally controlled input voltage level, mute, loopback and clip detection functions. The telecom codec can be directly connected to a Data Access Arrangement (DAA) and includes a built in sidetone suppression circuit

• Complete 4 wire resistive touch screen interface circuit supporting position, pressure and plate resistance measurements

• 10-bit successive approximation ADC with internal track and hold circuit and analog multiplexer for touch screen read-out and monitoring of four external high voltage (7.5V) analog voltages

• High speed, 4 wire serial interface data bus (SIB) for communication to the system controller

• 3.3V supply voltage and built in power saving modes make the UCB1300 optimal for portable and battery powered

applications

• Maximum operating current 25 mA

• 10 general purpose IO pins

APPLICATIONS

• Handheld Personal Computers, Personal Intelligent Communicators, Personal Digital Assistants

• Smart Mobile Phones

• Screen/Web Phones

• Internet Access Terminal

• Modems

UCB1300

GENERAL DESCRIPTION

The UCB1300 is a single chip, integrated mixed signal audio and telecom codec. The single channel audio codec is designed for direct connection of a microphone and a speaker. The built-in telecom codec can directly be connected to a DAA and supports high speed modem protocols. The incorporated analog-to-digital converter and the touch screen interface provides complete control and read-out of an 4 wire resistive touch screen. The 10 general purpose I/O pins provide programmable inputs and/or outputs to the system.

The UCB1300 has a serial interface bus (SIB) intended to communicate to the system controller. Both the codec input data and codec output data and the control register data are multiplexed on this SIB interface.

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

ORDERING INFORMATION

TYPE

NUMBER

NAME DESCRIPTION VERSION

UCB1300BE LQFP48 plastic low proﬁle quad ﬂat package; 48 leads; body 7 × 7 × 1.4 mm SOT313-2

BLOCK DIAGRAM

PACKAGE

IO(n)

TINP

TINN

TOUTP

TOUTN

MICP

MICGND

SKRP

SKRN

1 bit ADC

4 bit DAC

1 bit ADC

4 bit DAC

down sample filter

up sample filter

down sample filter

up sample filter

Digital IO circuits

data / control registers

Voltage reference

10 bit ADC

Fig.1 Block diagram.

Serial bus interface

Clock buffers &

sample rate

dividers

multiplexer

AD(n)

touch screen interface

SIBDIN SIBDOUT SIBSYNC IRQOUT

SIBCLK

TSPX,TSMX TSPY,TSMY

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

PINNING

SYMBOL PIN DESCRIPTION

RESET

STATE

IO7 1 general purpose I/O pins input I/O IO8 2 general purpose I/O pins input I/O IO9 3 general purpose I/O pins input I/O ADCSYNC 4 ADC synchronization pulse input - I V

SSD

5 digital ground - S n.c 6 not connected - V

SSA2

7 analog speaker driver ground - S SPKRN 8 negative speaker output Hi-Z O SPKRP 9 positive speaker output Hi-Z O V

DDA2

10 analog speaker driver supply - S TOUTP 11 positive telecom codec output Hi-Z O TOUTN 12 negative telecom codec output Hi-Z O TEST 13 test mode protection ‘0’ I TINN 14 negative telecom codec input Hi-Z I TINP 15 positive telecom codec input Hi-Z I VREFBYP 16 external reference voltage input Hi-Z I/O V V

DDA1 SSA1

17 analog supply - S

18 analog ground - S n.c 19 not connected - MICGND 20 microphone ground switch input Hi-Z I MICP 21 microphone signal input Hi-Z I AD3 22 analog voltage inputs Hi-Z I AD2 23 analog voltage inputs Hi-Z I AD1 24 analog voltage inputs Hi-Z I AD0 25 analog voltage inputs Hi-Z I V

SSA3

26 analog touch screen ground - S TSPY 27 positive Y-plate touch screen Hi-Z I/O TSMX 28 negative X-plate touch screen Hi-Z I/O TSMY 29 negative Y-plate touch screen Hi-Z I/O TSPX 30 positive X-plate touch screen Hi-Z I/O n.c 31 not connected - V

DDD

32 digital supply - S IO0 33 general purpose I/O pins input I/O IO1 34 general purpose I/O pins input I/O IO2 35 general purpose I/O pins input I/O IO3 36 general purpose I/O pins input I/O V

SSD

37 digital ground - S RESET 38 asynchronous reset input - I SIBSYNC 39 SIB synchronization input - I

TYPE

C C C

(2)

A A

A C A A

A A A A A A

A A A A

C C C C

C C

(1)

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

SYMBOL PIN DESCRIPTION

SIBDOUT 40 SIB data output ‘1’

RESET

STATE

(6)

SIBCLK 41 SIB serial interface clock − I SIBDIN 42 SIB data input − I IRQOUT 43 interrupt output ‘0’ O

TYPE

C C C

(1)

n.c 44 not connected −− IO4 45 general purpose I/O pins input I/O IO5 46 general purpose I/O pins input I/O IO6 47 general purpose I/O pins input I/O V

DDD

48 digital supply − S

C C C

Notes

1. I/OC= CMOS bidirectional; ID= digital input; S = supply; OA= analog output; IC= CMOS input; IA= analog input; I/OA= analog bidirectional; OC= CMOS output.

2. V

(pins 5 and 37) and V

SSD

(pin 18) are connected internally within the UCB1300.

SSA1

3. SKPRN/SPKRP (pins 8 and 9), TINN/TINP (pins 14 and 15) and TOUTP/TOUTN are differential pairs

4. TEST (pin 13) is connected to an internal pull-down resistor. This pin should be held LOW during normal operation of the circuit.

5. The ‘not connected’ pins (pins 6, 19, 31 and 44) are reserved for future applications and should be left floating.

6. SIBDOUT reset state is 1 until the SIB bus is running. SIBDOUT will be active once the SIB bus has started.

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

book, full pagewidth

IO7 IO8 IO9

ADCSYNC

SSD

n.c.

SSA2

SPKRN SPRKP

DDA2

TOUTP TOUTN

DDD

1 2 3 4 5 6 7 8

9 10 11 12

TEST

IO5

IO6

TINP

TINN

n.c.

IO4

UCB1300

DDA1VSSA1

IRQOUT

XXX

VREFBYP

SIBCLK

SIBDIN

n.c.

MICGND

SIBDOUT

MICP

RESET

SIBSYNC

AD3

AD2

SSD

AD1

36 35 34 33 32 31 30 29 28 27 26 25

MXXxxx

IO3 IO2 IO1

IO0 V

DDD

n.c.

TSPX

TSMY TSMX TSPY

SSA3

AD0

Fig.2 Pin configuration.

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

FUNCTIONAL DESCRIPTION

The UCB1300 consists of several analog and digital sub-circuits which can be programmed via the Serial Interface Bus (SIB). This enables the user to set the UCB1300 functionality according to actual application requirements.

AUDIO CODEC

The audio codec contains an input channel, built up with a 64 timesoversampling sigma delta analog todigital converter (ADC) with digital decimation filters and a programmable gain microphone preamplifier. The programmable gain microphone amplifier features a built-in offset cancellation stage, which reduces the distortion of this stage at high gain settings, caused by the offset voltages of the internal amplifiers or leakage on the board. It can be deactivated (reg13, bit 13) for improved performance at low gain settings. A general rule is that below a gain setting of 16 (24dB gain) the offset cancellation circuit will reduce THD and signal bandwidth and should then be deactivated.

The output path consists of a digital up-sample filter, a 64 time oversampling 4-bit digital-to-analog converter (DAC) circuit followed by a BTL speaker driver, capable of driving a 16 Ω speaker. The output path features a digital programmable attenuation and a mute function.

The audio codec also incorporates a loopback mode, in which codec output path and the input path are connected in series.

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

AUD_GAIN[4,3] AUD_OFF_CAN AUD_LOOP AUD_GAIN[2..0]

MICP

MICGND

VCCSPKR

SPKRP

SPKRN

VSSSPKR

AUD_MUTE AUD_ATT[2..0]

Fig.3 Audio codec block diagram.

4-bit DAC

1-bit ADC

DIGITAL ATTENUATOR

AUD_ATT[4,3]

DIGITAL DECIMATION FILTER

AUD_IN_ENA

AUD_OUT_ENA

DIGITAL NOISE SHAPER

The audio sample rate (fsa) is derived from the SIB interface clock pin (SIBCLK) and is programmable through the SIB interface using AUD_DIV[n]. The audio sample rate is given by the following equation:

×()

SIBCLK

-------------------------------------------------64 AUD_DIV[n]×()

(7< AUD_DIV[n] < 128)

For example,a serial clock of 9.216 MHz, with a divisorof 12, results inan audio sample rate of 24.0 kHz. Both therising and the falling edges of SIBCLK are usedin case AUD_DIV[n]is set toan odd number,which demands a50% duty cycle of SIBCLK to obtain time equidistant sampling.

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

DDA1

MICP

MICGND

SSA1

PASSIVE

UCB1300 UCB1300

DDA1

MICGND

MICP

SSA1

ACTIVE

Fig.4 Possible microphone connections.

The UCB1300audio codec inputpath accepts microphone signalsdirectly, only a DC blocking capacitor isneeded since the MICP input is biased around 1.4V. The ‘ground’ side of the microphone is either connected to the analog ground (V

) or to the MICGND pin. The latter will decrease the current consumption of active microphones, since the

SSA1

MICGND pin is made Hi-Z when the audio codec input path is disabled. The full scale input voltage of the audio input path is programmable in1.5 dB steps by setting the appropriate number in

AUDIO_GAIN[n] in the audio control register A. Using very high gains may require the use of the internal offset cancellation circuit programmable in reg 13 to avoid clipping in the ADC.

A clipdetection circuit will inform theuser whenever the input voltage exceeds the maximum inputvoltage, since this will lead to a high distortion. In that case AUD_CLIP_STAT in the audio control register B is set. When ACLIP_RIS_INT is set, an interrupt is generated on the IRQOUT pin on the rising edge of the clip detect signal. When ACLIP_FAL_INT is set, an interrupt is generated on the falling edge of the clip detect signal.

The frequency response of the audio codec depends mainly on the selected sample rate, since the bandwidth is limited in the down and up sampling filters. These digital filters both contain several FIR and IIR low pass filters and a DC removal filter(high pass filter). A third-order smoothing filter is implemented in the DAC path,between DAC and speaker driver stage to reduce the spurious frequencies at the speaker outputs.

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

48dB

24dB

0dB

21dB

0dB

24dB

programmed attenuation

48dB 69dB

Fig.5 Analog and digital attenuation settings audio output path.

The output level can be attenuated in 3 dB steps down to -69 dB. The first 8 attenuation steps (0 to 21 dB) are implemented in the analog domain. The digital up sample filter contains a 24 dB and a 48 dB attenuation setting. This arrangement preservesthe resolution, thus the ‘audio quality’ of the audio output signal for attenuationsettings till 21 dB.

The speaker driver is muted when AUDIO_MUTE in the audio control register B is set. The speaker driver will remain activated in that case, however no signal is produced by the speaker driver circuit.

The speaker driver is designed to directly drive a Bridge Tied Load (BTL). This yields the highest output power and this arrangementdoes notrequire external DC blocking capacitors.The speakerdriver alsoaccepts single-endedconnection of a speaker, in which case the maximum output power is reduced to a quarter of the BTL situation. Consequently this way of connecting the speaker to the speaker driver reduces the power consumption of the speaker driver in the UCB1300 by a factor of 2. Fig.6 shows possible ways to connect a speaker to the driver. Loading the amplifiers with a capacitive load may cause high frequency oscillations and should be done cautiously.

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

BRIDGE TIED SPEAKER LOAD

UCB1300 UCB1300 UCB1300

SPKRP 9

8 SPKRN

SINGLE-ENDED SPEAKER CONNECTIONS

SPKRP 9

8 SPKRN

SPKRP 9

8 SPKRN

Fig.6 Possible speaker connections.

The audioinput and outputpath are activated independently.The input pathis enabled when AUDIO_IN_ENAis set, the output path is enabled when AUD_OUT_ENA is set in the audio control register B. This provides the user the means to reduce the current consumption of the UCB1300 if one part of the audio codec is not used in the application.

The audio codec has a loopback mode for system test purposes, which is activated when the AUDIO_LOOP bit in the audio control register B is set. This is an analog loopback which internally connects the output of the audio output path to the input of the audio input path, (see Fig.3). In this mode the normal microphone input is ignored, but the speaker driver can be operated normally.

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

TELECOM CODEC

The telecom codec contains an input channel, built up from a 64 times oversampling sigma delta analog-to-digital converter (ADC) with digital decimation filters, programmable attenuation gain and built-in sidetone suppression circuit.

The output path consist of a digital up-sample filter, a 64 times oversampling 4-bit digital-to-analog converter (DAC) circuit followed by a differential output driver, capable of directly driving a 600 Ω isolation transformer. The output path includes a mute function. The telecom codec also incorporates a loopback mode, in which codec output path and the input path are connected in series.

TOUTP

TOUTN

TINP

TINN

TEL_SIDE_ENA

SIDETONE

SUPPRESSION

CIRCUIT

TEL_MUTE

TEL_ATTATT TEL_GAIN

1-bit ADC

4-bit DAC

DIGITAL DECIMATION FILTER

TEL_IN_ENA

TEL_OUT_ENA

DIGITAL NOISE SHAPER

Fig.7 Telecom codec block diagram.

The telecom sample rate (fst) is derived from the SIB interface clock pin (SIBCLK) and is programmable through the SIB interface. The telecom sample rate is given by the following formula:

×()

------------------------------------------------- -

SIBCLK

64 TEL_DIV[n]×()

(15 < TEL_DIV[n] <128)

For example, a SIBCLK of 9.216 MHz, with a divisor of 40, results in a telecom sample rate of 7.2 kHz. Both the rising and the falling edges of the SIBCLK are usedin case TEL_DIV[n] is set to an odd number. In that case a 50% duty cycle of the SIBCLK signal is mandatory to obtain time equidistant sampling.

The input path of the telecom codec has a programmable attenuation gain. It also implements a voice band filter, which consists ofa digital low pass filter,which is a part of the decimation filter. Therefore the pass band of the voice band filter

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

is determinedby the selectedtelecom codec sample rate.This voice bandfilter is activated bysetting TEL_VOICE_ENA in the telecom control register B. The resulting telecom input filter curves are given in Fig.38 and Fig.39.

The output section of the telecom codec is designed to interface with a 600 Ω line through an isolation transformer. The built-in mutefunction is activated byTEL_MUTE in the telecom control register B. The output driver remainsactive in the mute mode, howeverno output signal is produced. Loading the drivers with a capacitive load may cause high frequency oscillations and should be done cautiously.

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

TOUCH SCREEN MEASUREMENT MODES

The UCB1300 contains an on-chip interface for a 4 wire resistive touch screen. This interface supports three modes of touch screen measurements: position, pressure and plate resistance.

POSITION MEASUREMENT

Twoposition measurementsare needed to determine thelocation ofthe pressedspot. Firstan Xmeasurement, secondly a Y measurement. The Xplate is biasedduring the X position measurement of theX plate andthe voltage onone or both Y terminals (TSPY, TSMY) measured. The circuit can then be represented by a potentiometer, with the TSPY and/or TSMY electrode being the ‘wiper’. The measured voltage on the TSPY/TSMY terminal is proportional to the X position of the pressed spot of the touch screen.

Vposition

Vtscbias

tspx

tsmy

tspy

tsmx

Fig.8 Touch screen setup for position measurement.

In the Y position mode the X plate and Y plate terminals are interchanged, thus the Y plate is biased while the voltage on the TSPX and/or TSMX terminal is measured.

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

PRESSURE MEASUREMENT

The pressure used to press the touch screen can be determined. In fact, the contact resistance between the X and Y plate is measured, which is a good indication of the size of the pressed spot and the applied pressure. A soft stylus, e.g. a finger, leads to a rather large contact area between the two plates when a large pressure is applied. A hard stylus, e.g. a pen, leads to less variation in measured contact resistance since the contact area is rather small.

Vtscbias

ipressure

tspx

tsmy

tspy

tsmx

Fig.9 Touch screen setup for pressure measurement.

One plate is biased at one or both terminals during this pressure measurement, whereas the other plate is grounded, again on one or both terminals. The current flowing through the touch screen is a direct indication for the resistance between both plates. A compensation for the series resistance, formed by the touch screen plates itself will improve the accuracy ofthis measurement. The measurement is done with a resistive voltage divider. The internalresistor should be taken into account to evaluate the settling time of the pressure measurement given the board capacitors connected to the ADC tap point in pressure mode.

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

Vtscbias

Measured resistor

Switch matrix

To ADC

Internal resistor (about 1kΩ)

Fig.10 Pressure measurement scheme.

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Philips Semiconductors Product speciﬁcation

Advanced modem/audio analog front-end UCB1300

PLATE RESISTANCE MEASUREMENT

Theplate resistance of a touchscreen typicallyvaries alot due to processing spread.Knowing theactual plateresistance makes it possible to compensate for the plate resistance effects in pressure resistance measurements. The plate resistance decreases when two or more spots on the touch screen are pressed.In that case, a part of one plate, e.g. the X plate, is shorted by the other plate, which decreases the actual plate resistance

Vtscbias

iplate

tspx

tsmy

tspy

tsmx

Fig.11 Touch screen setup for plate resistance.

The plate resistance measurement is executed in the same way as the pressure resistance measurement. In this case only one of the two plates is biased and the other plate is kept floating. The current through the connected plate is again a direct indication of the connected resistance.

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