DS8627/DS8628 130/225 MHz Low Power Prescalers General Description The DS8627 and DS8628 are low power fixed ratio prescalers which divide by 24 and 20, respectively. The inputs can be driven either single or double-ended and they are buffered, providing 40/100 mVrms input sensitivity. The output provided is open-collector and is capable of interfacing with TTL and CMOS. The device can be used in phase-locked loop applications such as FM radio or other communications bands to prescale the input frequency down to a more usable level. A digital frequency display system can also be derived separately or in conjunction with a phase-locked loop, and it can extend the useful range of many inexpensive frequency counters to 225 MHz. Features Y Y Y Input frequency: 130 MHz (-4, -3); 225 mHz (-2, std) Low power: 10 mA (-4, -2); 7 mA (-3, std) Input sensitivity: 100 mVrms (-4, -3); 40 mVrms (-2, std) Logic and Connection Diagrams DS8627 ( d 24) TL/F/5009 – 1 DS8628 ( d 20) TL/F/5009 – 2 Dual-In-Line Package TL/F/5009 – 3 Top View Order Number DS8627N or DS8628N (-4, -3, -2) See NS Package Number N08E C1995 National Semiconductor Corporation TL/F/5009 RRD-B30M115/Printed in U. S. A. DS8627/DS8628 130/225 MHz Low Power Prescalers June 1986 Absolute Maximum Ratings (Note 1) Open-Collector Output Voltage If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. VCC Supply Voltage Storage Temperature Range 7V k VCC VIN Input Voltage 7V Operating Free Air Temperature Range b 30§ C to a 70§ C b 65§ C to a 150§ C Recommended Operating Conditions Symbol Parameter DS8627-4 DS8628-4 Conditions Min DS8627-3 DS8628-3 Max Min 4.5 5.5 20 130 300 VCC Supply Voltage fMAX Toggle Frequency VIN Input Signal Amplitude 100 VSLW Slew Rate 20 IOL Low Level Output Current VIN e 100 mVrms DS8627-2 DS8628-2 Max Min 4.5 5.5 20 130 100 300 20 DS8627 DS8628 Units Max Min 4.5 5.5 4.5 5.5 V 20 225 20 225 MHz 40 300 40 300 mVrms 20 Max 20 3 3 DS8627-4 DS8628-4 DS8627-3 DS8628-3 DS8627-2 DS8628-2 Min Min Min V/ms 3 mA DC Electrical Characteristics (Notes 2 and 3) Symbol Parameter Conditions Max Max DS8627 DS8628 Max Min Units Max ICEX Open-Collector High Level Output Output e 5.5V 100 100 100 100 mA VOL Low Level Output Voltage VCC e 4.5V, IOL e 3 mA 0.4 0.4 0.4 0.4 V ICC Supply Current VCC e 5.5V 10 7 10 7 mA AC Electrical Characteristics VCC e 5V g 10%, TA e b30§ C to a 70§ C Parameter Conditions Min RIN Symbol AC Input Resistance VIN e 100 MHz and 50 mVrms 1.0 CIN Input Capacitance 3 Max Units kX 10 pF Note 1: ‘‘Absolute Maximum Ratings’’ are those values beyond which the safety of the device cannot be guaranteed. Except for ‘‘Operating Temperature Range’’ they are not meant to imply that the devices should be operated at these limits. The table of ‘‘Electrical Characteristics’’ provides conditions for actual device operation. Note 2: Unless otherwise specified min/max limits apply across the b 30§ C to a 70§ C temperature range. Note 3: All currents into device pins are shown as positive, out of device pins as negative, all voltages referenced to ground unless otherwise noted. All values shown as max or min on absolute value basis. 2 Application Hints tions under no signal (open circuit) conditions. In addition, in the single ended mode, a capacitor of 0.001 mF should be connected between the unused input and the ground plane to provide a good high frequency bypass. The capacitor should be made larger for lower frequencies. The input waveform may be sinusoidal, but below about 20 MHz the operation of the circuit becomes dependent on the slew rate of the input rather than amplitude. A square wave input with a slew rate of greater than 20 V/ms will permit correct operation down to lower frequencies, provided the proper input coupling capacitor is provided. OPERATING NOTES The signal source is usually capacitively coupled to the input. At higher frequencies a 0.001 mF input capacitor is usually sufficient, with larger values used at the lower frequencies. If the input signal is likely to be interrupted, it may be desirable to connect a 100 kX resistor between one input and ground to stabilize the device. In the single-ended mode, it is preferable to connect the resistor to the unused input. In the differential mode, the resistor can be connected to either input. The addition of the 100 kX pull-down resistor causes a loss of input sensitivity, but prevents circuit oscilla- Schematic Diagrams TL/F/5009 – 5 TL/F/5009 – 4 Typical Application TL/F/5009 – 6 3 DS8627/DS8628 130/225 MHz Low Power Prescalers Physical Dimensions inches (millimeters) Molded Dual-In-Line Package (N) Order Number DS8627N or DS8628N (-4, -3, -2) NS Package Number N08E LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 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