24lc21a Microchip Technology Inc., 24lc21a Datasheet
24lc21a
Available stocks
Related parts for 24lc21a
24lc21a Summary of contents
Page 1
... Industrial (I): -40°C to +85°C Description The Microchip Technology Inc. 24LC21A is a 128 x 8-bit dual-mode Electrically Erasable PROM. This device is designed for use in applications requiring storage and serial transmission of configuration and control informa- tion. Two modes of operation have been implemented: Transmit-only mode and Bidirectional mode ...
Page 2
... ELECTRICAL CHARACTERISTICS (†) Absolute Maximum Ratings V .............................................................................................................................................................................7.0V CC All inputs and outputs w.r. .........................................................................................................................................- Storage temperature ...............................................................................................................................- +150 C Ambient temperature with power applied ................................................................................................- +125 C ESD protection on all pins † NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device ...
Page 3
... Schmitt Trigger inputs which provide noise and specification for standard operation. I 24LC21A Units Remarks kHz (Note 1) ns (Note 1) ns After this period the first clock pulse is generated ns Only relevant for repeated ...
Page 4
... FUNCTIONAL DESCRIPTION The 24LC21A is designed to comply to the DDC Standard proposed by VESA (Figure 3-3) with the exception that it is not Access.bus capable. It operates in two modes, the Transmit-only mode and the Bidirectional mode. There is a separate 2-wire protocol to support each mode, each having a separate clock input but sharing a common data line (SDA) ...
Page 5
... Bidirectional mode Clock (SCL), controls access to the bus and generates the Start and Stop conditions, while the 24LC21A acts as the slave. Both master and slave can operate as transmitter or receiver, but the master device determines which mode is activated. In the Bidirectional mode, the 24LC21A only responds to commands for device 1010 000X ...
Page 6
... VESA’s Display Data Channel (DDC) Standard Proposal ver. 2p rev. 0, used by permission of VESA. 2: The dash box and text “The 24LC21A and... inside dash box.” are added by Microchip Technology Inc. 3: Vsync signal is normally used to derive a signal for VCLK pin on the 24LC21A. ...
Page 7
... Note: Once switched into Bidirectional mode, the 24LC21A will remain in that mode until power is removed. Removing power is the only way to reset the 24LC21A into the Transmit-only mode. 3.1.5 ACKNOWLEDGE Each receiving device, when addressed, is obliged to generate an acknowledge after the reception of each byte ...
Page 8
... After generating a Start condition, the bus master transmits the slave address consisting of a 7-bit device code (1010000) for the 24LC21A. The eighth bit of slave address determines whether the master device wants to read or write to the 24LC21A (Figure 3-7). The 24LC21A monitors the bus for its corresponding slave address continuously ...
Page 9
... Page Write The write control byte, word address and the first data byte are transmitted to the 24LC21A in the same way byte write. But instead of generating a Stop condition the master transmits up to eight data bytes to the 24LC21A which are temporarily stored in the on- chip page buffer and will be written into the memory after the master has transmitted a Stop condition ...
Page 10
... FIGURE 4-1: BYTE WRITE BUS ACTIVITY R MASTER T SDA LINE S BUS ACTIVITY VCLK FIGURE 4-2: VCLK WRITE ENABLE TIMING SCL SDA IN VCLK T VHST FIGURE 4-3: PAGE WRITE S T BUS ACTIVITY A CONTROL MASTER R BYTE T SDA LINE BUS ACTIVITY K VCLK DS21160F-page 10 CONTROL WORD BYTE ...
Page 11
... Setting VCLK high allows normal write operations, while setting VCLK low prevents writing to any location in the array. Connecting the VCLK pin to V allow the 24LC21A to operate as a serial ROM, although this configuration would prevent using the device in the Transmit-only mode. DS21160F-page 11 ...
Page 12
... Then the master issues the control byte again but with the R/W bit set to a one. The 24LC21A will then issue an acknowledge and transmits the 8-bit data word. The master will not acknowledge the transfer but does generate a Stop condition and the 24LC21A discontinues transmission (Figure 7-2) ...
Page 13
... K BUS ACTIVITY 2003 Microchip Technology Inc WORD CONTROL R ADDRESS BYTE DATA n+2 DATA n 24LC21A S T DATA DATA n DS21160F-page 13 ...
Page 14
... PIN DESCRIPTIONS 8.1 SDA This pin is used to transfer addresses and data into and out of the device, when the device is in the Bidirectional mode. In the Transmit-only mode, which only allows data to be read from the device, data is also transferred on the SDA pin. This pin is an open drain terminal, ...
Page 15
... APPENDIX A: REVISION HISTORY Revision F Corrections to Section 1.0, Electrical Characteristics. 2003 Microchip Technology Inc. 24LC21A DS21160F-page 15 ...
Page 16
... To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office PART NO. X /XX Device Temperature Package Range Device 24LC21A Dual Mode Serial EEPROM 24LC21AT Dual Mode Serial EEPROM (Tape and Reel) Temperature Range Blank + - +85 C Package P ...
Page 17
... Use of Microchip’s products as critical com- ponents in life support systems is not authorized except with express written approval by Microchip. No licenses are con- veyed, implicitly or otherwise, under any intellectual property rights. 2003 Microchip Technology Inc. Trademarks The Microchip name and logo, the Microchip logo, Accuron, dsPIC ...
Page 18
... Via Quasimodo, 12 20025 Legnano (MI) Milan, Italy Tel: 39-0331-742611 Fax: 39-0331-466781 Netherlands Biesbosch 14 NL-5152 SC Drunen, Netherlands Tel: 31-416-690399 Fax: 31-416-690340 United Kingdom 505 Eskdale Road Winnersh Triangle Wokingham Berkshire, England RG41 5TU Tel: 44-118-921-5869 Fax: 44-118-921-5820 07/28/03 2003 Microchip Technology Inc. ...