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ST25W08M1TR データシート(PDF) 3 Page - STMicroelectronics |
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ST25W08M1TR データシート(HTML) 3 Page - STMicroelectronics |
3 / 16 page Mode RW bit MODE Bytes Initial Sequence Current Address Read ’1’ X 1 START, Device Select, RW = ’1’ Random Address Read ’0’ X1 START, Device Select, RW = ’0’, Address, ’1’ reSTART, Device Select, RW = ’1’ Sequential Read ’1’ X 1 to 1024 Similar to Current or Random Mode Byte Write ’0’ X 1 START, Device Select, RW = ’0’ Multibyte Write (2) ’0’ VIH 8 START, Device Select, RW = ’0’ Page Write ’0’ VIL 16 START, Device Select, RW = ’0’ Notes: 1. X = VIH or VIL 2. Multibyte Write not available in ST24/25W08 versions. Table 4. Operating Modes (1) Device Code Chip Enable Block Select RW Bit b7 b6 b5 b4 b3 b2 b1 b0 Device Select 1 0 1 0 E A9 A8 RW Note: The MSB b7 is sent first. Table 3. Device Select Code When writing data to the memory it responds to the 8 bits received by asserting an acknowledge bit during the 9th bit time. When data is read by the bus master, it acknowledges the receipt of the data bytes in the same way. Data transfers are termi- nated with a STOP condition. Power On Reset: VCC lock out write protect. In order to prevent data corruption and inadvertent write operations during power up, a Power On Reset (POR) circuit is implemented. Until the VCC voltage has reached the POR threshold value, the internal reset is active, all operations are disabled and the device will not respond to any command. In the same way, when VCC drops down from the operating voltage to below the POR threshold value, all operations are disabled and the device will not respond to any command. A stable VCC must be applied before applying any logic signal. SIGNAL DESCRIPTIONS Serial Clock (SCL). The SCL input pin is used to synchronize all data in and out of the memory. A resistor can be connected from the SCL line to VCC to act as a pull up (see Figure 3). Serial Data (SDA). The SDA pin is bi-directional and is used to transfer data in or out of the memory. It is an open drain output that may be wire-OR’ed with other open drain or open collector signals on the bus. A resistor must be connected from the SDA bus line to VCC to act as pull up (see Figure 3). Chip Enable (E). This chip enable input is used to set one least significant bit (b3) of the device select byte code. This input may be driven dynamically or tied to VCC or VSS to establish the device select code. Protect Enable (PRE). The PRE input pin, in ad- dition to the status of the Block Address Pointer bit (b2, location 3FFh as in Figure 7), sets the PRE write protection active. Mode (MODE). The MODE input is available on pin 7 (see also WC feature) and may be driven dynami- cally. It must be at VIL or VIH for the Byte Write mode, VIH for Multibyte Write mode or VIL for Page Write mode. When unconnected, the MODE input is internally read as a VIH (Multibyte Write mode). Write Control (WC). An hardware Write Control (WC) feature is offered only for ST24W08 and ST25W08 versions on pin 7. This feature is usefull to protect the contents of the memory from any erroneous erase/write cycle. The Write Control sig- nal is used to enable (WC = VIH) or disable (WC = VIL) the internal write protection. When uncon- nected, the WC input is internally read as VIL and the memory area is not write protected. 3/16 ST24/25C08, ST24/25W08 |
同様の部品番号 - ST25W08M1TR |
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同様の説明 - ST25W08M1TR |
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