Overall Function:

The SC14402 is a mixed-signal processor designed for DECT (Digital Enhanced Cordless Telecommunications) applications. It combines digital processing capabilities with analog functions like ADC, DAC, microphone interfaces, and loudspeaker outputs. It also has features to support battery management and testing.

Key Pin Categories & Description


1. Power & Ground:

️· Digital Supply Voltages: Several pins are dedicated to digital power (e.g., pins 67, 68).
️· Digital Grounds: Several pins are dedicated to digital ground (e.g., pins 66).
️· Analog Supply Voltages: Designated pins for analog power (e.g., pin 61).
️· Analog Grounds: Pins for analog ground (e.g., pin 62).
️· Battery Voltage Inputs: Pins related to battery voltage monitoring (pins 46, 48, 50, 51).
️· Battery Charge Control: Pin for controlling battery charging (pin 52).

2. Reset & Hold:

️· Reset Input (Pin 68): Active-low reset input, includes an internal pull-down resistor, to initiate the device's startup.
️· Hold Input (Pin 69): A crucial pin for halting the processor's operations. When held low, it puts the device in a "hold" mode where the system bus interface is tri-stated, enabling external control by a CR16A microcontroller (common in DECT systems).

3. Address & Data Bus:

️· Address Pins (71-74, 84, 86, 87, 88, 93-95): Used for addressing memory and peripherals within the system. In "hold" mode, these pins become inputs.
️· Data Bus (82-75): A bidirectional data bus for transferring data.

4. Chip Select & Control Signals:

️· Auxiliary Chip Select (ACSn) (Pin 70): Used to select the SC14402 in a multi-chip system. It becomes active when the address range matches the chip's assigned region.
️· Read Signal (Pin 85): Active-low signal indicating a memory read operation.
️· Write Signal (Pin 92): Active-low signal indicating a memory write operation.
️· ROM Chip Select (Pin 83): Selects the internal ROM.

5. Analog Input/Output (Audio, ADC/DAC)

️· Microphone Input/Reference: Pins for connecting a microphone (positive and negative inputs/references - pins 53, 54, 55, 87).
️· Loudspeaker Output: Pins for outputting audio to a loudspeaker (positive and negative outputs - pins 59, 60).
️· Analog-to-Digital Converter (ADC) Inputs: Pins used for ADC conversions (pin 53).
️· Digital-to-Analog Converter (DAC) Output: Used to generate frequencies (pin 100).
️· External Capacitor (Pin 64): Needed for associated circuit.

6. Interrupt & Miscellaneous

️· Masked Interrupt Output (Pin 91): Used for generating interrupts.
️· Crystal Connection (Pin 65): For an external crystal oscillator (typically 10.368 MHz).
️· Buzzer Control (Pins 41, 42, 43): For controlling a buzzer or generating PWM signals.
️· Test Pins (Pin 49): For production testing.

Key "Hold" Mode Implications

The "Hold" mode (controlled by Pin 69) is vital for allowing an external microcontroller (CR16A) to control the SC14402's bus interface. When the SC14402 is in the "Hold" mode:

️· The SC14402's address and data bus pins become inputs.
️· The external microcontroller can access the SC14402's memory and peripherals directly.
️· This is common in DECT systems where a microcontroller manages the higher-level functions and communication.