Optical disc ICs Single-chip 4-bit microcontroller for CD-DA BU34675 The BU34675 is a compact 4-bit, single-chip microcontroller that includes all the I / O required for CD system control. Circuits on the chip include a pulse width measurement counter (PWC), SIO, and an LCD controller / driver for a 28-segment display. The LCD segments can all be switched in software to CMOS output, and the extensive I / O allows many functions with a low pin count. FApplications Portable CD-DA, CD / radio / cassette players FFeatures 1) Low-voltage, high-speed operation (VDD = 2.3 to 5.5V at 4.4MHz). 2) Pulse width measurement counter on chip (for remote control reception). 3) SIO provided for communication with the DSP. 4) Seven-segment, four-common LCD controller / driver on chip. 5) All segments of the LCD controller / driver output can be switched to CMOS output using software. FAbsolute maximum ratings (Ta = 25_C) FRecommended operating conditions (Ta = 25_C) 569 Optical disc ICs Block diagram 570 BU34675 Optical disc ICs BU34675 Pin descriptions 571 Optical disc ICs Input / output circuits 572 BU34675 Optical disc ICs BU34675 FElectrical characteristics (unless otherwise noted, Ta = 25_C and VDD = 5V) 573 Optical disc ICs FElectrical characteristics (unless otherwise noted, Ta = 25_C and VDD = 3V) 574 BU34675 Optical disc ICs Explanation of the hardware (1) Operates of a single power supply (VDD = 2.3 to 5.5V). (2) Memory size ROM: 6144 8 bits RAM: 256 4 bits LCD display RAM : 7 4 bits (3) Instruction time (one cycle instruction) 1.5µsec (at 4 MHz) (4) Sub-routine nesting: . . . . . . . . . . . . . . . . . 8 levels (5) Interrupts: 5 External . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Internal (timer counter, serial I / O) . . . . . . . . . 2 (6) ROM data table function (6k data table region) (7) Two power save modes STOP / HALT BU34675 (8) On-chip 7-segment LCD driver that can drive a wide variety of display types Bias . . . . . . . . . . . . . . 1 / 3 Duty variation . . . . . . 1 / 3, 1 / 4 (programmable) Internal bias resistors (approximately 50kΩ 3 stages) (9) LCD segment output can be switched to CMOS output by software. The COM3 pin and upper three segments are one-bit units, and the lower four segments are all selected together. At reset, switches to CMOS low-current output port with low level polarity. (10) Remote control receiver circuit (pulse width measurement) (11) On-chip 8-bit timer counter (12) On-chip I / O system makes interfacing with external LSI easy (LSB first). (13) 8 I / O lines that can be pulled up by software (14) 4 input lines that can be pulled up by software External dimensions (Units: mm) 575