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STK12C68-5C55M датащи(PDF) 8 Page - List of Unclassifed Manufacturers |
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STK12C68-5C55M датащи(HTML) 8 Page - List of Unclassifed Manufacturers |
8 / 10 page STK12C68-M 4-60 EEPROM cells. The nonvolatile data can be recalled an unlimited number of times. AUTOMATIC RECALL During power up, or after any low power condition (V CAP < VSWITCH), when VCAP exceeds the sense voltage of V SWITCH, a RECALL cycle will automatically be initiated. After the initiation of this automatic RE- CALL , if V CAP falls below VSWITCH, then another RE- CALL operation will be performed whenever V CAP again rises above V SWITCH. If the STK12C68-M is in a WRITE state at the end of power-up RECALL, the SRAM data will be corrupted. To help avoid this situation, a 10K Ohm resistor should be connected between W and system V CC. HARDWARE PROTECT The STK12C68-M offers hardware protection against inadvertent STORE operation during low voltage conditions. When V CAP < VSWITCH, all externally initiated STORE operations will be inhibited. HSB OPERATION The Hardware Store Busy pin (HSB) is an open drain circuit acting as both input and output to perform two different functions. When driven low by the internal chip circuitry it indicates that a STORE operation (initi- ated via any means) is in progress within the chip. When driven low by external circuitry for longer than t ASSERT, the chip will conditionally initiate a STORE operation after t DELAY. READ and WRITE operations that are in progress when HSB is driven low (either by internal or external cir- cuitry) will be allowed to complete before the STORE operation is performed, in the following manner. After HSB goes low, the part will continue normal SRAM operations for t DELAY. During tDELAY, a transition on any address or control signal will terminate SRAM operation and cause the STORE to commence. Note that if an SRAM write is attempted after HSB has been forced low, the write will not occur and the STORE operation will begin immediately. Hardware-Store-Busy (HSB) is a high speed, low drive capability bi-directional control line. In order to allow a bank of STK12C68-Ms to perform synchronized STORE functions, the HSB pin from a number of chips may be connected together. Each chip contains a small inter- nal current source to pull HSB HIGH when it is not being driven low. To decrease the sensitivity of this signal to noise generated on the PC board, it may optionally be pulled to V CCX via an external resistor with a value such that the combined load of the resistor and all parallel chip connections does not exceed I HSB_OL at V OL. Do not connect this or any other pull-up to the V CAP node. If HSB is to be connected to external circuits other than other STK12C68-Ms, an external pull-up resistor should be used. During any STORE operation, regardless of how it was initiated, the STK12C68-M will continue to drive the HSB pin low, releasing it only when the STORE is complete. Upon completion of a STORE operation, the part will be disabled until HSB actually goes HIGH. AUTOMATIC STORE OPERATION During normal operation, the STK12C68-M will draw current from V CCX to charge up a capacitor connected to the V CAP pin. This stored charge will be used by the chip to perform a single STORE operation. After power up, when the voltage on the V CAP pin drops below V SWITCH, the part will automatically disconnect the V CAP pin from VCCX and initiate a STORE operation. Figure 1 shows the proper connection of capacitors for automatic store operation. The charge storage capaci- tor should have a capacity of at least 100 µF (± 20%) at 6V. Each STK12C68-M must have its own 100 µF capacitor. Each STK12C68-M must have a high quality, high frequency bypass capacitor of 0.1 µF connected between V CAP and VSS, using leads and traces that are as short as possible. If the AutoStore™ function is not required, then V CAP should be tied directly to the power supply and V CCX should be tied to ground. In this mode, STORE opera- tions may be triggered through software control or the HSB pin. In either event, V CAP (Pin 1) must always have a proper bypass capacitor connected to it. In order to prevent unneeded STORE operations, auto- matic STOREs as well as those initiated by externally driving HSB LOW will be ignored unless at least one |
Аналогичный номер детали - STK12C68-5C55M |
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Аналогичное описание - STK12C68-5C55M |
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