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Electronic Components Datasheet Search |
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MF4 Datasheet(PDF) 2 Page - National Semiconductor (TI) |
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MF4 Datasheet(HTML) 2 Page - National Semiconductor (TI) |
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Block Diagram (Continued) Pin Descriptions Pin Pin Function # Name 1 CLK IN A CMOS Schmitt-trigger input to be used with an external CMOS logic level clock. Also used for self clocking Schmitt-trigger oscillator (see section 1.1). 2 CLK R A TTL logic level clock input when in split supply operation (±2.5V to ±7V) with L. Sh tied to system ground. This pin becomes a low impedance output when L. Sh is tied to V −. Also used in conjunction with the CLK IN pin for a self clocking Schmitt-trigger oscillator (see section 1.1). The TTL input signal must not exceed the supply voltages by more than 0.2V. 3 L. Sh Level shift pin; selects the logic threshold levels for the clock. When tied to V − it enables an internal tri-state buffer stage between the Schmitt trigger and the internal clock level shift stage thus enabling the CLK IN Schmitt-trigger input and making the CLK R pin a low impedance output. When the voltage level at this input exceeds 25% (V + −V−)+V− the internal tri-state buffer is disabled allowing the CLK R pin to become the clock input for the internal clock level-shift stage. The CLK R threshold level is now 2V above the voltage on the L. Sh pin. The CLK R pin will be compatible with TTL logic levels when the MF4 is operated on split supplies with the L. Sh pin connected to system ground. 5 FILTER OUT The output of the low-pass filter. It will typically sink 0.9 mA and source 3 mA and swing to within 1V of each supply rail. 6 AGND The analog ground pin. This pin sets the DC bias level for the filter section and must be tied to the system ground for split supply operation or to mid-supply for single supply operation (see section 1.2). When tied to mid-supply this pin should be well bypassed. 7, 4 V +,V− The positive and negative supply pins. The total power supply range is 5V to 14V. Decoupling these pins with 0.1 µF capacitors is highly recommended. Pin Pin Function # Name 8 FILTER IN The input to the low-pass filter. To minimize gain errors the source impedance that drives this input should be less than 2K (see section 1.3 of the Application Hints). For single supply operation the input signal must be biased to mid-supply or AC coupled through a capacitor. www.national.com 2 |
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