TL F 5009
DS8627DS8628
130225
MHz
Low
Power
Prescalers
June 1986
DS8627 DS8628 130 225 MHz Low Power Prescalers
General Description
The DS8627 and DS8628 are low power fixed ratio prescal-
ers which divide by 24 and 20 respectively The inputs can
be driven either single or double-ended and they are buff-
ered 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 pre-
scale 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
Input frequency 130 MHz (-4 -3) 225 mHz (-2 std)
Y
Low power 10 mA (-4 -2) 7 mA (-3 std)
Y
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
RRD-B30M115 Printed in U S A
Absolute Maximum Ratings
(Note 1)
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
V
CC
Supply Voltage
7V
V
IN
Input Voltage
k
V
CC
Open-Collector Output Voltage
7V
Operating Free Air Temperature Range
b
30 C to
a
70 C
Storage Temperature Range
b
65 C to
a
150 C
Recommended Operating Conditions
DS8627-4
DS8627-3
DS8627-2
DS8627
Symbol
Parameter
Conditions
DS8628-4
DS8628-3
DS8628-2
DS8628
Units
Min
Max
Min
Max
Min
Max
Min
Max
V
CC
Supply Voltage
4 5
5 5
4 5
5 5
4 5
5 5
4 5
5 5
V
f
MAX
Toggle Frequency
V
IN
e
100 mVrms
20
130
20
130
20
225
20
225
MHz
V
IN
Input Signal Amplitude
100
300
100
300
40
300
40
300
mVrms
V
SLW
Slew Rate
20
20
20
20
V ms
I
OL
Low Level Output Current
3
3
3
mA
DC Electrical Characteristics
(Notes 2 and 3)
DS8627-4
DS8627-3
DS8627-2
DS8627
Symbol
Parameter
Conditions
DS8628-4
DS8628-3
DS8628-2
DS8628
Units
Min
Max
Min
Max
Min
Max
Min
Max
I
CEX
Open-Collector High Level Output
Output
e
5 5V
100
100
100
100
m
A
V
OL
Low Level Output Voltage
V
CC
e
4 5V
0 4
0 4
0 4
0 4
V
I
OL
e
3 mA
I
CC
Supply Current
V
CC
e
5 5V
10
7
10
7
mA
AC Electrical Characteristics
V
CC
e
5V
g
10% T
A
e b
30 C to
a
70 C
Symbol
Parameter
Conditions
Min
Max
Units
R
IN
AC Input Resistance
V
IN
e
100 MHz and 50 mVrms
1 0
kX
C
IN
Input Capacitance
3
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
OPERATING NOTES
The signal source is usually capacitively coupled to the in-
put At higher frequencies a 0 001 mF input capacitor is usu-
ally sufficient with larger values used at the lower frequen-
cies 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-
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
Schematic Diagrams
TL F 5009 4
TL F 5009 5
Typical Application
TL F 5009 6
3
DS8627DS8628
130225
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
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failure to perform when properly used in accordance
support device or system or to affect its safety or
with instructions for use provided in the labeling can
effectiveness
be reasonably expected to result in a significant injury
to the user
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