Standard ICs FL tube driver BU2879AK The BU2879AK is a driver IC for fluorescent displays. It is equipped with 26 high-voltage withstand outputs and can display from 11 segments of 15 characters to 16 segments of 8 characters. This IC is equipped with a key scanning function, and general-purpose input pins, and is ideal for front panels in VTRs and other equipment. A serial interface allows functions to be controlled from a microcomputer. Applications •VCRs •1)Features High withstanding voltage output. 5) Key scanning function (6 × 4). 6) Internal pull-down resistance (high voltage withstand output). 7) QFP 44 package. 2) Display modes: 11S × 15G ~ 16S × 8G. 3) Variable display luminance (7 steps). 4) 3-wire serial interface. •Absolute maximum ratings (Ta = 25°C, V SS Parameter = 0V) Symbol Limits Unit Applied voltage 1 VDD – 0.3 ~ + 7.0 V Applied voltage 2 VEE Input voltage VIN V VDD + 0.3 ~ VDD – 40 V – 0.3 ~ VDD + 0.3 Pd 850∗ Operating temperature Topr – 25 ~ + 75 °C Storage temperature Tstg – 55 ~ + 125 °C Power dissipation mW Note) Operation is not guaranteed at these values. Note) Power dissipation is reduced by 8.5mW for each increase in Ta of 1°C over 25°C. ∗ When mounted on a 70 × 70 × 1.6mm glass epoxy board •Recommended operating conditions (Ta = 25°C, V SS Parameter Symbol = 0V) Min. Typ. Max. Unit Operating power supply voltage 1 VDD 4.5 5.0 5.5 V Operating power supply voltage 2 VEE VDD – 37 VDD – 35 VDD – 0 V 1 Standard ICs BU2879AK •Block diagram CS SCK SI VSS SO 8bit shift-REG. VDD OSC OSC CONTROL LOGIC 16bit latch SW4 4bit data G1 SW1 GRID Driver 16bit × 15word DISPLAY DATA RAM K4 KEY DATA latch (4 × 6) G10 K1 SEGMENT Driver S1 2 S / G Driver S11 S12 / G15 S16 / G11 VEE Standard ICs BU2879AK •Pins descriptions Pin No. Pin 14, 38 VDD Power supply pin 1 Name Oscillation pin I/O Function Input Connected to system power supply. 44 OSC 7, 43 VSS Ground pin Input Connected to system ground. 6 SI Serial data input Input Serial data input starting from MSB 5 SO Serial data output Output 8 SCK Serial clock input Input Serial data read at rising edge. 9 CS Serial chip select Input Serial initialization when LOW, valid at HIGH. 15 ~ 25 S1 ~ S11 27 VEE 42 ~ 39, 37 ~ 32 G1 ~ G10 S12 / G15 ~ 26, 28 ~ 31 S16 / G11 10 ~ 13 K1 ~ K4 1~4 SW1 ~ SW4 Input / output Capacitor connection pin for oscillation High-voltage withstand output pin for segment Serial data output starting from MSB; output is Nch open drain. Output pin for segment; output is Pch open drain + pull-down resistance. Output Power supply pin 2 Input Pull-down resistance connection for FLP driver output. High-voltage withstand output pin for grid Output Output pin for grid; output is Pch open drain + pull-down resistance. High-voltage withstand output pin for segment / grid Output Used to switch output between segment and grid; output is Pch open drain + pull-down resistance. Key data input pin Input Data input pin for key scanning. General-purpose input pin Input General-purpose input pin; input data can be transmitted serially to microcomputer. •Electrical characteristics (unless otherwise noted, Ta = 25°C, V DD Parameter Symbol Min. Typ. Supply current IDD — Input threshold voltage VIN Input current = 5V, VSS = 0V, VDD – VEE = 35V) Measurement circuit Max. Unit — 5 mA 44-pin attachment, at 1000pF oscillation Fig.1 1.5 — 3.5 V Pins 1 to 4, 6, 8, 9 to 13 Fig.4 IIN — — 10 µA Pins 1 to 4, 6, 8, 9 to 13 Fig.2 OSC oscillation frequency FOSC 130 200 300 kHz 44-pin attachment, at 1000pF oscillation Fig.3 Segment output current IOseg 6 — — mA Pins 15 to 26, 28 to 31, VO = VDD – 2V∗ Fig.2 Grid output current IOgrd 18 — — mA Pins 26, 28 to 37, 39 to 42, VO = VDD – 2V∗ Fig.2 Leakage current when OFF IOFF — — 10 µA Pins 15 to 26, 28 to 37, VO = VDD – VEE Fig.2 Output pull-down resistance RD 35 70 140 kΩ Pins 15 to 26, 28 to 37 Fig.2 FMAX — — 1 MHz Design guarantee value Fig.3 TSH 0.16 — — µs — — — µs — — Maximum operating frequency Conditions 〈Serial transmission〉 Input data hold Input data setup TSS 0.16 — Output data delay TD — — 0.3 µs — — TSCYC 0.5 — — µs — — TSW 40 — 60 % Input clock cycle Input clock "H" width At minimum input clock cycle — ∗ For the high voltage withstand output pins for the segment / grid of pins 26 and 28 to 31, when segment output is specified, segment output current is output, and when grid output is specified, grid current is output. 3 Standard ICs BU2879AK •Measurement circuits A VEE VDD VEE VDD 1000p n = Test pin n OSC VSS VSS Fig.1 Fig.2 VEE VDD VEE A V VDD 1000p OSC G1 Monitor VSS VSS Fig.3 Fig.4 •Electrical characteristic curves 3.7 3.6 3.5 3.4 3.3 3.2 – 25 25 75 TEMPERATURE: Ta (°C) Fig. 5 Supply current temperature characteristics 4 54 16 “H” SEGMENT OUTPUT CURRENT: IOHseg (mA) “H” GRID OUTPUT CURRENT: IOHgrd (mA) CIRCUIT CURRENT: IDD (mA) 3.8 50 46 42 38 34 30 – 25 15 14 13 12 11 10 25 75 TEMPERATURE: Ta (°C) Fig. 6 “H” grid output current temperature characteristics – 25 25 75 TEMPERATURE: Ta (°C) Fig.7 “H” segment output current temperature characteristics Standard ICs BU2879AK •External dimensions (Units: mm) 14.0 ± 0.3 10.0 ± 0.2 23 22 44 12 2.15 ± 0.1 0.05 1 0.8 11 0.35 ± 0.1 1.2 14.0 ± 0.3 10.0 ± 0.2 33 34 0.15 ± 0.1 0.15 QFP44 5