Communication ICs Panel interface for telephones BU8317KV The BU8317KV is a large-scale integrated circuit which enables a serial input / output interface between the key input required for panel boards used in PHS systems, portable telephones, and telephone answering machines and LED and LCD control functions. It reduces the number of wiring harnesses needed between the main board in the telephone and the panel board, and takes some of the processing load off the main CPU. Applications PHS systems, portable telephones, telephone answering machines Features 1) 7 7 keypad matrix interface. 2) 12-bit LED driver. (6 bits can also function as input pins) 3) 4-column 32-segment LCD driver. (internal bias-generating resistor) 4) Standby mode. 5) VQFP80 package. Absolute maximum ratings (unless otherwise noted, Ta = 25C) Recommended operating conditions (Ta = 25C) 295 Communication ICs Block diagram Pin descriptions 296 BU8317KV Communication ICs BU8317KV 297 Communication ICs Input / output circuits 298 BU8317KV Communication ICs BU8317KV Electrical characteristics (unless otherwise noted, Ta = 25C, VDD=2.7 to 5.5V) 299 Communication ICs Timing charts 300 BU8317KV Communication ICs BU8317KV Measurement circuits 301 Communication ICs BU8317KV Data formats (Serial data is input and output with the MSB coming first.) (1) Reading data SR R1XR7, C1XC7 L7XL12 (2) LED resitor writing command L1XL12 (3) : Used for LED control. LED lights up with “1” and is unlit with “0”. LCD register writing command LC01XLC04 LS01XLS32 302 : Outputs SR pin status. Pressing a key (low level) outputs “1” and releasing the key (high level) outputs “0”. A “0” is output is the key is not pressed on low level. : Outputs key data. Pressing a key outputs “1” and not pressing the key outputs “0”, when on low level. : Outputs parallel input data. Output “1” when the pin is on high level and “0” when it is on low level. : Selects LCD common. “1” means select and “0” means do not select. Segment control is active on the selected common, only. Multiple commons can be selected simultaneously. : Used for LCD segment control. Lights up with “1” and is unlit with “0”. Communication ICs (4) (5) BU8317KV All LEDs, LCDs activate command Used to clear non-active status of all LEDs and LCDs. All LEDs, LCDs non-active command Temporarily turns off all LEDs and LCDs, while holding the LED and LCD register settings as they are. LCD output changes to low level and the bias current channel is cut. (6) Register reset command Resets all LED and LCD resisters to “0”. Clears stand-by mode. Non-active status of all LEDs and LCDs changes to active status. 303 Communication ICs Recommended method for inputting / outputting data (1) Control command serial input (2) 304 Key data serial output BU8317KV Communication ICs BU8317KV FStandby mode (1) Setting the standby mode S The standby mode is set by setting RE to L and WE to L. S Oscillation stops and the line current falls to an extremely low level. S The contents of the LED and LCD registers are reset (all data cleared to 0), and all LEDs and LCDs are turned off. S The LCD output goes LOW, and the bias current channel is cut off. S The only effective key input is the SR key; no input is accepted from the keypad. (2) Cancelling the standby mode S The standby mode is cancelled by executing the register reset command. S Setting SR to LOW in any state other than RE = LOW and WE = LOW immediately cancels the standby mode. S Setting SR to LOW when RE = LOW and WE = LOW initiates oscillation but does not cancel the standby mode. Setting SR to HIGH stops oscillation once again.(If “on debounce” is valid for the SR key and KD has output a LOW level, oscillation continues until an “off debounce” becomes valid.) Standby mode setting example 1 2 3 4 5 6 7 At RE = LOW, WE = LOW, the standby mode is set, and oscillation stops. In standby mode, no input is accepted. Setting the SR pin to LOW initiates oscillation even in the standby mode. (SR = LOW takes priority over RE = LOW, WE = LOW.) When the SR pin is open (HIGH), RE = LOW and WE = LOW, so oscillation stops and the standby mode continues to be effective. Setting the SR pin LOW initiates oscillation even in the standby mode. When RE = LOW, WE = LOW is no longer true, the standby mode is cancelled, and oscillation continues even if the SR pin is open (HIGH). Data is set in the output serial register at the falling edge of RE and when SR = LOW, and can be read. 305 Communication ICs Oscillation frequencies LCD drive wave forms This is a time-shared drive system in which 1 / 3 bias and 1 / 4 duty alternate between two frames. The figure at the right shows the drive wave forms for the following conditions : LC01-LSxx : Lighted LC02-LSxx : Not lighted LC03-LSxx : Lighted LC04-LSxx : Not lighted 306 BU8317KV Communication ICs BU8317KV Configuring a booster circuit This shows an example of booster circuit configuration for a VLCD pin, using the CPC and CPCB pins. Configuring an LCD bias correction circuit This shows an example of correction circuit configuration for the LCD output voltage, using the V3 pin. 307 Communication ICs BU8317KV Precautions when turning on the power supply The power supply should be turned on when RE = LOW and WE = LOW, and the registers should then be reset using the register reset command. Precautions concerning data input and output (1) Serial output of key data when several keys are pressed at the same time is as shown at the right. The key data when 1. and (1) are pressed at the same time is the same as the key data when 2. and 3. are pressed at the same time. (2) If the LED and LCD registers are rewritten, all of the bits should be written, and not just the pertinent bits. Electrical characteristic curve 308 External dimensions (Units: mm)