Optical disc ICs Single-chip 4-bit microcontroller for CD-DA BU34381 The BU34381 is a 4-bit microcomputer designed for CD-DA players, and has a wide array of internal I / O components, including an 8-bit, 8-channel AD converter, pulse width counter (PWC), two serial I / O, and an LCD controller / driver capable of displaying up to 80 segments. All LCD segments are programmable for CMOS output. These I / O components allow for multifunction applications with a low number of pins. FApplications Portable CD-DA players, portable CD stereos FFeatures 1) High speed operations and low voltage. (VDD = 2.7 X 5.5V at 4.4MHz) 2) Internal 8-bit, 8-channel AD converter. 3) Internal pulse width counter. 4) Two internal serial input / outputs. 5) Internal 20-segment, 4-common LCD controller / driver. (usable with 3 commons) 6) All segments output by the LCD controller / driver are programmable for CMOS output. FAbsolute maximum ratings (Ta = 25_C) FRecommended operating conditions (Ta = 25_C) 91 Optical disc ICs Block diagram 92 BU34381 Optical disc ICs BU34381 Pin assignments Pin descriptions 93 Optical disc ICs 94 BU34381 Optical disc ICs BU34381 Input / output circuits 95 Optical disc ICs FElectrical characteristics (at 5V) (unless otherwise noted, Ta = 25_C, VDD = 5V) 96 BU34381 Optical disc ICs BU34381 97 Optical disc ICs FElectrical characteristics (at 3V) (unless otherwise noted, Ta = 25_C, VDD = 3V) 98 BU34381 Optical disc ICs Hardware descriptions (1) Operates on a single power supply (VDD = 2.7 X 5.5V) (2) Memory size 8 bits ROM : 12288 4 bits RAM : 512 LCD display RAM : 20 4 bits (3) Instruction execution time (1 cycle instruction) 1.5µsec: (at 4MHz) (4) Subroutine nesting : 8 levels (5) Interrupts : 6 factors External : 3 factors Internal (time counter, serial I / O) : 3 factors (6) ROM data table function (data table area: 12KB) (7) Two energy-saving modes (STOP / HALT) (8) Internal 20-segment LCD driver adaptable for various types of displays Bias :1/3 Duty settings : 1 / 3, 1 / 4 (programmable) Internal bias resistor (3 stages, approx. 50kΩ) BU34381 (9) LCD segment output is program-switchable to CMOS output All 20 segments can be selected in 4-bit groups Resetting: CMOS small-current output port, LOW polarity (10) Internal remote control receiver (pulse width counter) (11) Internal 8-channel, 8-bit A / D converter (12) A / D input is programmable in 1-bit units as digital input (13) Internal 8-bit timer counter (also used as event counter) (14) Two internal serial input / outputs (LSB fast) that simplify interface with external LSI chips (15) 12 input / outputs (programmable pull-up) (16) 5 inputs (programmable pull-up) 99 Optical disc ICs External dimensions (Units: mm) 100 BU34381