TWL1110

` 2.7 to 3.3-V Operation
` Designed for Analog and Digital Wireless Handsets and Telecommunications Applications
` Two Differential Microphone Inputs
` Differential Earphone Outputs and One Single-Ended Earphone Output
` Earphone and Microphone Mute
` Programmable Transmit, Receive, and Sidetone Paths With Extended Gain and Attenuation Ranges
` Programmable for 15-Bit Linear Data or 8-Bit Companded (-law and A-law) Mode
` Supports PCM Clock Rates of 128 kHz and 2.048 MHz
` Pulse Density Modulated (PDM) Buzzer Output
` On-Chip I2C Bus, Which Provides Simple,Standard, Two-Wire Serial Interface With Digital ICs
` Dual-Tone Multifrequency (DTMF) and Single-Tone Generator Capable of Up to 8-kHz Tone With Three Selectable Resolutions of 7.8125 Hz, 15.625 Hz, and 31.25 Hz
` 2-Channel Auxiliary Multiplexer (MUX) (Analog Switch)
` Capable of Driving 32 Down to a 8- Speaker
` Programmable Power Down Modes
` Pin Compatible to TI's TWL1102, TWL1103,and TWL1109 Devices for TQFP only
` Available in a 32-Pin Thin Quad Flatpack (TQFP) Package and MicroStar Junior BGA

The TWL1110 provides extended gain and attenuation flexibility for transmit, receive, and sidetone paths. A differential earphone output is capable of driving speaker loads as low as 8 for use in speaker phone applications. The single tone function on the TWL1110 generates a single tone output of up to 8 kHz. The resolution of the DTMF tone is also selectable to 7.8125 Hz, 15.625 Hz, or 31.250 Hz through the interface control. The analog switch provides more control capabilities for voice-band audio processor (VBAP).

The TWL1110 VBAP is an analog-digital interface for voice band signals designed with a combination of coders and decoders (codecs) and filters. TWL1110 is a low-power device with companding options and programming features, and it meets the requirements for communication systems, including the cellular phone. The device operates in either the 15-bit linear or 8-bit companded (-law or A-Law) mode, which is selectable through the I²C interface.

A coder, an analog-to-digital converter or ADC, digitizes the analog voice signal, and a decoder, an digital-to-analog converter or DAC, analogs the digital-voice signal. VBAP provides a companding option to overcome the bandwidth limitations of telephone networks without degradation in sound quality. The human auditory system is a logarithmic system in which high amplitude signals require less resolution than low amplitude signals. Therefore, an 8-bit code word with nonuniform quantization (-law or A-law) has the same quality as 13-bit linear coding. TWL1110 VBAP provides better digital code words by generating a 15-bit linear coding option.

The human voice is effective from a frequency range of 300 Hz to 3300 Hz in telephony applications. In order to eliminate unwanted signals, the VBAP design has two types of filters that operate in both the transmit and receive path. A low-pass filter attenuates the signals over 4 kHz. A selectable high-pass filter cleans up the signals under 100 Hz. This reduces noise that may have coupled in from 50/60-Hz power cables. The high-pass filter is bypassed by selecting the corresponding register bit. TWL1110 VBAP has many programming features that are controlled using a 2-wire standard serial I²C interface. This allows the device to interface with many digital ICs such as a DSP or a microprocessor. The device has seven registers: power control, mode control, transmit PGA, receive PGA, high DTMF, low DTMF, and auxiliary mode control. Some of the programmable features of TWL1110 that can be controlled by I2C interface include:
` Transmit amplifier gain
` Receive amplifier gain
` Sidetone gain
` Volume control
` Earphone control
` PLL power control
` Microphone selection
` Transmit channel high-pass filter control
` Receive channel high-pass filter control
` Companding options and selection control
` PCM loopback
` DTMF control
` Pulse density modulated control

The TWL1110 VBAP is also capable of generating its own internal clocks from a 2.048-MHz master clock input.