Datenblatt-Suchmaschine für elektronische Bauteile |
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FM33256 Datenblatt(PDF) 2 Page - Ramtron International Corporation |
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FM33256 Datenblatt(HTML) 2 Page - Ramtron International Corporation |
2 / 28 page FM33256/FM3316 SPI Companion w/ FRAM Rev. 2.0 Feb. 2009 Page 2 of 28 Pin Configuration Pin Name Function /CS Chip Select SCK Serial Clock SI Serial Data Input SO Serial Data Output PFI Power Fail Input PFO Power Fail Output (NMI) CNT Event Counter Input ACS Alarm/Calibration/SqWave /RST Reset Input/Output X1, X2 Crystal Connections VDD Supply Voltage VBAK Battery-Backup Supply VSS Ground Pin Descriptions Pin Name Type Pin Description /CS Input Chip Select: This active low input activates the device. When high, the device enters low- power standby mode, ignores the SCK and SI inputs, and the SO output is tri-stated. When low, the device internally activates the SCK signal. A falling edge on /CS must occur prior to every op-code. SCK Input Serial Clock: All I/O activity is synchronized to the serial clock. Inputs are latched on the rising edge and outputs occur on the falling edge. Since the device is static, the clock frequency may be any value between 0 and 16 MHz and may be interrupted at any time. SI Input Serial Input: All data is input to the device on this pin. The pin is sampled on the rising edge of SCK and is ignored at other times. It should always be driven to a valid logic level to meet IDD specifications. The SI pin may be connected to SO for a single pin data interface. SO Output Serial Output: This is the data output pin. It is driven during a read and remains tri-stated at all other times. Data transitions are driven on the falling edge of the serial clock. The SO pin may be connected to SI for a single pin data interface. CNT Input Event Counter Input: This input increments the counter when an edge is detected on this pin. The polarity is programmable and the counter value is nonvolatile or battery-backed, depending on the mode. This pin should be tied to ground if unused. ACS Output Alarm/Calibration/SquareWave: This is an open-drain output that requires an external pullup resistor. In normal operation, this pin acts as the active-low alarm output. In Calibration mode, a 512 Hz square-wave is driven out. In SquareWave mode, the user may select a frequency of 1, 512, 4096, or 32768 Hz to be used as a continuous output. The SquareWave mode is entered by clearing the AL/SW and CAL bits in register 18h. X1, X2 I/O 32.768 kHz crystal connection. When using an external oscillator, apply the clock to X1 and a DC mid-level to X2 (see Crystal Type section for suggestions). /RST I/O Reset: This active-low output is open drain with weak pull-up. It is also an input when used as a manual reset. This pin should be left floating if unused. PFI Input Early Power-fail Input: Typically connected to an unregulated power supply to detect an early power failure. This pin must be tied to ground if unused. PFO Output Early Power-fail Output: This pin is the early power-fail output and is typically used to drive a microcontroller NMI pin. PFO drives low when the PFI voltage is <1.5V. VBAK Supply Backup supply voltage: A 3V battery or a large value capacitor. If no backup supply is used, this pin should be tied to VSS and the VBC bit should be cleared. The trickle charger is UL recognized and ensures no excessive current when using a lithium battery. VDD Supply Supply Voltage. VSS Supply Ground VDD PFI ACS SCK PFO SI RST VSS X1 VBAK CNT 1 2 3 4 5 6 7 14 13 12 11 10 9 8 X2 SO CS |
Ähnliche Teilenummer - FM33256_09 |
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Ähnliche Beschreibung - FM33256_09 |
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