PCA1070
Key Features
- Line interface with: - Voltage regulator with programmable DC voltage drop - Programmable set impedance - Output to control an external switching MOS transistor for pulse dialling - Programmable DC voltage during pulse dialling - Circuitry for short DC settling time
- Interface to peripheral circuits with: - Supply for microcontroller and DTMF diallers - Input to sense supply voltage of microcontroller and output for reset of microcontroller - I2C-bus (programming of parameters, control of all logic signals) - High impedance DTMF signal input - Input for external oscillator signal with on-chip DC blocking - Power-down via the I2C-bus - Stabilized supply for electret microphone
- Microphone and DTMF amplifiers: - Low-noise microphone preamplifier suitable for various types of microphones - Symmetrical high impedance microphone preamplifier inputs - Programmable gain for microphone and DTMF channels - Sending mute via the I2C-bus to disable microphone amplifier and enable DTMF amplifier - Sending mute also to be used as privacy switch - Dynamic limiting (speech controlled) to prevent distortion of line signal and sidetone; programmable maximum sending level
- Receiving amplifier: - Suitable for various types of earpieces (including piezo) - Programmable gain and hearing protection level - Receiving mute via the I2C-bus to disable receiving amplifier and enable DTMF confidence tone - On-chip anti-sidetone circuit with programmable sidetone balance - Confidence tone in the earpiece during DTMF dialling PCA1070
- Facility to regulate parameters with line current: - Value of DC line current (bit code) readable via the I2C-bus - Line loss compensation with fully software programmable characteristics (control range, stop current) of microphone/earpiece/DTMF amplifiers - Fully software programmable control of sidetone balance and DC voltage drop as a function of line length. APPLICATIONS
- Wired telephony (basic till feature phones)
- Combi-terminals (e.g. telephone and answering machine or FAX)
- Modems and base units of cordless telephones. GENERAL DESCRIPTION The PCA1070 is a CMOS integrated circuit performing all speech and line interface functions in fully electronic telephone sets. The device requires a minimum of external components. The transmission parameters are programmable via the I2C-bus. This makes the IC adaptable to nearly all worldwide country requirements and to a various range of speech transducers, without changing the (few) external components. The parameters are stored in the EEPROM of a microcontroller and are loaded into the PCA1070 during the start-up phase of the transmission IC after hook-off. The PCA1070 also allows adaptation to the connected telephone line by reading the line current via the I2C-bus and processing it in the microcontroller. 1997 Jun 20 2 Philips Semiconductors Product specification Multistandard programmable analog CMOS transmission IC
