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6 page 
6 AT60142F/FT 4408A–AERO–02/05 AC Characteristics Temperature Range:................................................ -55 +125 °C Supply Voltage:........................................................ 3.3 +0.3V Input Pulse Levels: .................................................. GND to 3.0V Input Rise and Fall Times: ....................................... 3ns (10 - 90%) Input and Output Timing Reference Levels: ............ 1.5V Output Loading I OL/IOH: ............................................ See Figure 1 Figure 1. AC Test Loads Waveforms Data Retention Mode Atmel CMOS RAM's are designed with battery backup in mind. Data retention voltage and supply current are guaranteed over temperature. The following rules insure data retention: 1. During data retention chip select CS must be held high within V CC to VCC -0.2V. 2. Output Enable (OE) should be held high to keep the RAM outputs high imped- ance, minimizing power dissipation. 3. During power-up and power-down transitions CS and OE must be kept between V CC + 0.3V and 70% of VCC. 4. The RAM can begin operation > t R ns after VCC reaches the minimum operation voltages (3V). Figure 2. Data Retention Timing |
