Standard ICs ID ROM for CRT displays supporting plug & play BU9881 / BU9881F The BU9881 / BU9881F is a 1k bit EEPROM conforming to the standardized interface that enables Plug & Play on CRT displays. Applications •Desktop CRT displays Desktop LCD displays Other desktop PC displays External CRT displays for notebook computers •1)Features 1kbit serial EEPROM with configuration of 128 words × 8 bits. 2) Supports I2C bus. 3) Supports DDC1™/ DDC2™ interfaces for monitor IDs. 4) Supports clock frequencies of 100kHz and 400kHz. 5) Switching from DDC2 to DDC1 enabled using mode pin. ∗ DDC is a registered trademark of VESA. •Absolute maximum ratings (Ta = 25°C) Parameter Applied voltage Power dissipation BU9881 Symbol Limits Unit VCC – 0.3 ~ + 6.5 V Pd BU9881F Storage temperature Tstg Operating temperature Topr Voltage for various pins — 500∗1 350∗2 mW – 65 ~ + 125 °C – 40 ~ + 85 °C – 0.3 ~ VCC + 0.3 V ∗1 Reduced by 5.0mW for each increase in Ta of 1°C over 25°C. ∗2 Reduced by 3.5mW for each increase in Ta of 1°C over 25°C. ∗ If input exceeds the absolute maximum ratings, the device may break down. •Recommended operating conditions Symbol Limits Unit Power supply voltage VCC 2.7 ~ 5.5 V Input voltage VIN 0 ~ VCC V Parameter 1 Standard ICs BU9881 / BU9881F •Block diagram MODE 1,024 bit EEPROM Array 1 2 N.C. 3 Address decoder VCC 7 VCLK 6 SCL 5 SDA 8bit 7bit N.C. 8 Slave-word address register 7bit START Data register STOP Control circuit GND 4 High voltage generator Power supply voltage detection ACK •Pin descriptions Pin No. Pin name I/O 1 MODE I 2, 3 N.C. — Not connected 4 GND — Reference voltage of 0V for all input / output 5 SDA I/O 6 SCL I 7 VCLK I 8 VCC — Function Transmit-only mode switching pin (pulled down when used in open state) Slave and word address serial data input / output Serial clock input pin for I2C mode Clock input pin for transmit-only mode Connect the power supply 䊊The SDA pin is Nch open drain output, and should be used with an external pull-up resistor added. 2 Standard ICs BU9881 / BU9881F •Electrical characteristics (unless otherwise noted, Ta = – 40 to + 85°C, Vcc = 2.7V to 5.5V) Symbol Min. Input high level voltage 1 VIH1 Input low level voltage 1 VIL1 Input high level voltage 2 VIH2 Input low level voltage 2 Measurement Circuit Max. Unit 0.7VCC — V (SCL, SDA) — — 0.3VCC V (SCL, SDA) — 2.0 — V (VCLK) — VIL2 — — 0.8 0.4 V VCC = 4.5 ~ 5.5V (VCLK) VCC = 2.7 ~ 4.5V (VCLK) — Input high level voltage 3 VIH3 0.8VCC — V (MODE) — Input low level voltage 3 VIL3 — 0.4 V (MODE) Output low level voltage VOL — 0.4 V IOL = 3.0mA(SDA) Fig.1 Input leakage current 1 ILI1 –1 1 µA VIN = 0V ~ VCC (SCL · SDA · VCLK) Fig.2 Input leakage current 2 ILI2 –1 15 µA VIN = 0V ~ VCC (MODE) Fig.2 Parameter Conditions — Output leakage current ILO –1 1 µA VOUT = 0V ~ VCC (SDA) Fig.2 Operating current consumption ICC — 3 mA VCC = 5.5V, tWR = 10ms Fig.3 Standby current ISB — 30 µA VCC = 5.5V, MODE = GND VCLK · SDA · SCL = VCC Fig.4 •Measurement circuits VCC VCC VCC 3.0mA A SDA GND V VOL VCC ILO ILI MODE, VCLK SDA, SCL GND VOUT = 0 ~ VCC VIN = 0 ~ VCC Data set when output is LOW Fig. 1 LOW output voltage measurement circuit Fig. 2 Input / output leakage current measurement circuit VCC VCC A 100 / 400 kHz clock Write / read input SCL, VCLK ICC VCC A VCC SCL ISB VCC MODE SDA SDA VCLK VCC MODE GND Fig. 3 Current consumption measurement circuit GND Fig. 4 Standby current measurement circuit 3 BU9881 / BU9881F Standard ICs •Operation timing characteristics (unless otherwise noted, Ta = – 40 to + 85°C) Parameter Symbol Standard Mode VCC = 2.7 ~ 5.5V Min. Max. High-speed Mode VCC = 4.5 ~ 5.5V Min. Max. Unit Clock frequency f SCL 0 100 0 400 kHz Data clock HIGH time t HIGH 4.0 — 0.6 — µs Data clock LOW time t LOW 4.7 — 1.3 — µs SDA / SCL rise time tR — 1.0 — 0.3 µs tF — 1.0 — 0.3 µs t HD: STA 4.0 — 0.6 — µs Start condition setup time t SU: STA 4.7 — 0.6 — µs Input data hold time t HD: DAT 0 — 0 — ns Input data setup time t SU: DAT 250 — 100 — µs Output data delay time t PD 0 3.5 0 0.9 µs Output data hold time t DH 0 — 0 — µs t SU: STO 4.7 — 0.6 — µs Bus release time prior to start of transfer t BUF 4.7 — 1.3 — µs Internal write cycle time t WR — 10 — 10 ms tI — — — 50 ns SDA / SCL fall time Start condition hold time Stop condition setup time Effective noise elimination interval (SCL, SDA pins) •Transmit – only MODE Parameter Standard Mode VCC = 2.7 ~ 5.5V High-speed Mode VCC = 4.5 ~ 5.5V Unit Min. Max. Min. Max. TVAA — 500 — 500 ns VCLK HIGH time TVHIGH 4.0 — 0.6 — µs VCLK LOW time TVLOW 4.7 — 1.3 — µs 夹Mode transition time TVHZ — 500 — 500 ns 夹Power up time for transmission TVPU 0 — 0 — ns VCLK output delay time 4 Symbol Standard ICs BU9881 / BU9881F •Circuit operation 䊊Basic operation The BU9881 / BU9881F is equipped with two modes, a normal I2C bus mode (bi-directional mode) and a transmitonly mode. • The transmit-only mode can be accessed by turning on the power supply to the IC, or by using the software to control the mode. In this mode, operation is synchronized to the clock input to VCLK, and it is possible to read the contents of the EEPROM memory from the SDA pin. • To switch from the transmit-only mode to the I2C bus mode, the clock signal that recognizes the switching of HIGH to LOW is input to the SCL pin. The I2C bus mode is effective following the edge of that clock. • To switch from the I2C bus mode to the transmit-only mode, the software can be used to control the mode, or the power supply to the IC can be turned off and then on again. This switches back to the transmit-only mode. (1) Description of mode pin functions As shown in the illustration below, the software can be used to control the mode pin, enabling switching from the I2C bus mode to the transmit-only mode. Set LOW for 2µs or longer Set HIGH for 2µs or longer MODE SCL I2C MODE TRANSMIT ONLY MODE I2C MODE Fig. 5 1)Transmit-only mode • This command causes all of the data written to the EEPROM to be read. After the transmit-only mode is entered, inputting the VCLK clock causes the data to be read from the SDA pin. • The SDA pin is in the "Hi-Z" state for the first nine clock signals input, and data is output sequentially, timed to the rise of the clock starting with the tenth clock. • Addresses are incremented automatically as clock pulses continue to be input to VCLK, with the data from the next address being read in sequence. While this is being done, the null bit (HIGH data) is output between the data of one address and that of the next address. • When the power supply is turned on, and when the mode is switched from the I2C bus mode to the transmit-only mode, the output data for the transmit-only mode is synchronized to VCLK as follows: Last address data→0h address data→1h address data→→→ and is incremented in sequence. (Following the last address, processing shifts to the 0h address.) Note: Reading in the transmit-only mode should not be done until the power supply has stabilized. When switching from the transmit-only mode to the I2C bus mode, assure the TVHZ time before beginning communications. 5 Standard ICs BU9881 / BU9881F VCC SCL 1 VCLK 2 9 TVAA TVPU HIGH-Z SDA 10 D7 D0 NULL D7 bit Last address MODE Don't Care 0h address Fig. 6 2) I2C bus mode 1. Start condition (start bit recognition) • Before executing the various commands, if SDA is HIGH, a start condition (start bit) must be in effect such that SDA changes from HIGH to LOW. • This IC constantly detects whether or not the start condition (start bit) is fulfilled for the SDA and SCL lines. If this condition is not fulfilled, no commands will be executed. (Refer to the section on synchronized data input / output timing.) 2. Stop condition (stop bit recognition) • When the various commands have been completed, a stop condition (stop bit) can be used to terminate the commands by raising SDA from LOW to HIGH if SCL is HIGH. (Refer to the section on synchronized data input / output timing.) 3. Precautions concerning the write command ∗ The stop bit cannot be executed in the write mode, so data that has been transmitted cannot be written to the memory. 4. Write protect In the I2C bus mode, the VCLK pin can be used as a write protect control pin. When the VCLK pin is HIGH, the byte write and page write commands function, but when the VCLK pin is LOW, these two writing commands are canceled. 6 Standard ICs BU9881 / BU9881F (2) Device addressing • The master address should be output first, followed by the start condition, and then the slave address. • The first four bits of the slave address are used to recognize the device type. The device code for this IC is fixed at "1010". • The next three bits of the slave address may be either HIGH or LOW. • The last bit of the slave address (R / W: READ / WRITE) is used to specify either writing or reading, and is as shown below. R / W set to 0: Writing (0 is also set in order to specify a word address for random reading.) R / W set to 1: Reading × 1010 × × R/W ×: Don't Care (3) ACK signal • This acknowledge signal (ACK signal) is determined by the software, and indicates whether or not the data has been correctly transmitted. Regardless of whether the address is a master or slave address, the device on the transmitter (sending signal) side (the µ-com when a slave address is input for a write command or a read command, and this IC when read command data is output) opens the bus after this 8-bit data is output. • With a device on the receiving (reception) side (this IC when a slave address is input for a read command or write command, and a microcomputer when data is output for a read command), SDA is set to LOW during the nine-clock cycle, and the acknowledge signal (ACK signal) is output when 8-bit data is received. • This IC output the acknowledge signal (ACK signal) in the LOW state after a start condition and a slave address (8 bits) have been recognized. • For other writing operations, the acknowledge signal (ACK signal) is output in the LOW state each time that 8-bit data (word address or write data) is received. • In the various reading operations, 8-bit data (read data) is output, and then the acknowledge signal (ACK signal) in the LOW state is detected. If the acknowledge signal (ACK signal) is detected and no stop condition is sent from the master (microcomputer) side, this IC continues to output data. If the acknowledge signal (ACK signal) is not detected, this IC interrupts the transmission of data, recognizes a stop condition (stop bit), and terminates the reading operation. The IC then enters the standby mode. (Refer to "Fig. 7 acknowledge signal (ACK signal) response.") Start condition SCL (from µ-COM) 1 8 9 SDA (µ-COM output data) SDA (data output from this IC) Acknowledge signal (ACK signal) Fig. 7 Acknowledge signal (ACK signal) response (When slave address is input for writing or reading) 7 Standard ICs BU9881 / BU9881F •I C synchronous data input / output timing 2 tF tR t HIGH SCL t LOW t HD: DAT t SU: DAT t HD: STA SDA (input) t BUF t DH t PD SDA (output) Fig. 8 SCL t SU: STA t HD: STA t SU: STO SDA START BIT STOP BIT Fig. 9 • Reading of input is done at the rising edge of SCL. • Output of data is synchronized to the falling edge of SCL. •Write cycle timing MODE “L” VCLK “H” SCL H SDA L D0 Write data (n address) ACK t WR Stop condition Fig. 10 Write cycle timing 8 Start condition Standard ICs BU9881 / BU9881F charts •(1)Timing Write cycle MODE “L” VCLK “H” Start condition Stop condition 1 8 9 17 26 18 27 SCL 1 SDA 1 0 0 0 0 0 0 0 × WA6 Write data Word address Slave address D0 D7 WA0 ACK signal (output) ×: Don't Care Fig. 11 Byte write cycle 1) Data is written to the address specified by the word address (n address). 2) After 8 bits of data are input, a stop bit is generated. This initiates writing of the data to the memory cell. MODE “L” VCLK “H” Stop condition Start condition 9 27 18 54 SCL SDA 1 0 1 0 0 Slave address 0 0 0 0 × WA6 Word address WA0 D0 D7 Write data D0 D7 Write data n+7 ACK signal (output) ×: Don't Care Fig. 12 Page write cycle 3) This command enables writing of 8 bytes of data. 4) This page write command is used to specify any of the first four bits (WA6 to WA3) of the word address. The address is incremented internally, and up to 8 bytes of data can be written to the last three bits (WA2 to WA0). 9 Standard ICs BU9881 / BU9881F (2) Read cycle MODE “L” VCLK Don't Care Start condition SCL 1 SDA 1 Stop condition 8 1 0 0 0 0 0 9 18 D7 1 D6 Slave address D2 D5 D1 D0 1 Read data ACK signal (output) ACK signal (input) Fig. 13 Current read cycle 1) With this IC, an internal address counter circuit increments the address one address at a time, and stores in memory the last word address (n address) for which the Write or read command was executed. 2) This command reads only the data of the word address (n +1 address) following the last word address to be written after the previous command has been executed. 3) If the ACK signal LOW following D0 is detected and no stop condition is sent from the master (microcomputer) side, reading can be continued sequentially to the data of the next word address. [The entire 1 kilobit (128 words) can be read.] (Refer to "Fig. 15 Sequential read cycle.") 4) To terminate this command, HIGH is input for the ACK signal following D0, and the SDA signal rises at the HIGH state of the SCL signal (stop condition), terminating the command. MODE“L” VCLK Don't Care Start condition Stop condition Start condition SCL SDA 1 0 1 0 0 Slave address 0 0 0 0 × WA6 WA0 1 Word address 0 1 0 0 Slave address 0 0 1 D7 D0 1 Read data ACK signal (input) ACK signal (output) Fig. 14 Random read cycle 5) This command enables reading of the data at the specified word address. 6) If the ACK signal LOW following D0 is detected and no stop condition is sent from the master (microcomputer) side, reading can be continued sequentially to the data of the next word address. [The entire 1 kilobit (128 words) can be read.] (Refer to "Fig. 15 Sequential read cycle.") 7) To terminate this command, HIGH is input for the ACK signal following D0, and the SDA signal rises at the HIGH state of the SCL signal (stop condition), terminating the command. 10 Standard ICs BU9881 / BU9881F MODE “L” VCLK Don't Care Start condition Stop condition SCL 1 SDA 0 1 0 0 0 0 1 D7 Slave address D7 D0 D0 Read data Read data n+a ACK signal (output) ACK signal (input) Fig. 15 Sequential read cycle (Example: For current reading) 8) If the ACK signal LOW following D0 is detected and no stop condition is sent from the master (microcomputer) side, reading can be continued sequentially to the data of the next word address. [The entire 1 kilobit (128 words) can be read.] 9) To terminate this command, HIGH is input for the ACK signal following any D0, and the SDA signal rises at the HIGH state of the SCL signal (stop condition), terminating the command. 10) Sequential reading is also possible with random reading. 11) With earlier ICs, switching from the DDC1 (transmit-only) mode to the DDC2 (I2C bus) mode was possible only by turning off the power supply and then turning it on again. With the BU9881 / BU9881F, however, switching between the normal I2C bus mode and the transmit-only mode can be done by controlling the mode pin (pin 1). 1. Controlling the mode pin (pin 1) from the main controller As shown in the figure below, the mode pin can be controlled through the software to switch from the I2C bus mode to the transmit-only mode. Set LOW for 2µs or longer Set HIGH for 2µs or longer MODE SCL 2 I C MODE TRANSMIT ONLY MODE 2 I C MODE Fig. 16 11 Standard ICs BU9881 / BU9881F 2. Controlling the mode pin (pin 1) through an attachment Vcc VCLK SCL SDA MODE N.C. N.C. GND As shown at the left, if there is no SCL input for approximately 2 seconds (min.) to 6 seconds (max.) after the DDC2 (I2C bus) mode has been terminated with the diode, resistor, and capacitor, the mode changes automatically to the DDC1 (transmit-only) mode. 62kΩ 100µF Fig.17 •External dimensions (Units: mm) BU9881 BU9881F 9.3 ± 0.3 5.0 ± 0.2 2.54 0.5 ± 0.1 0° ~ 15° 5 1 4 1.27 0.15 ± 0.1 4.4 ± 0.2 6.2 ± 0.3 0.3 ± 0.1 8 1.5 ± 0.1 7.62 0.11 4 0.51Min. 3.2 ± 0.2 3.4 ± 0.3 1 5 6.5 ± 0.3 8 0.4 ± 0.1 0.3Min. 0.15 DIP8 12 SOP8