sp8789 ETC-unknow, sp8789 Datasheet - Page 4

• Manufacturer Part Number: sp8789
• Description: 225mhz ? 20/21 Two Modulus Divider
• Manufacturer: ETC-unknow

OPERATING NOTES
1. The clock input (Pin 5) should be capacitively coupled to
the signal source. The input signal path is completed by
coupling a capacitor from the internal bias decoupling, Pin 6 to
ground.
2. The output stage which is normally open collector (Pin 2
open circuit) can be interfaced to CMOS. The open collector
canbereturnedtoa +10Vlineviaa5kresistorbuttheoutput sink
current should not exceed 2mA. If interfacing to TTL is
required then Pins 2 and 7 should be connected together to
give a fan-out = 1. This will increase supply current by
approximately 2mA.
3. The circuit will operate down to DC but a slew rate of better
than 20V/~s is required.
4. The mark space ratio of the output is approximately 1.2:1
at 200MHz.
Figure 5 : Typical impedance. Test conditions: supply voltage 5.2V, ambient temperature 25 C, frequencies in
OUTPUT
CONTROL
INPUT
VCC OF MODULUS
CONTROL DEVICE
MHz, impedance normalised to 50 ohms.
Figure 6 : Toggle frequency test circuit
1
2
3
4
SP8789
8
7
6
5
1n
5. Input impedance is a function of frequency. See Fig.5.
6. If no signal is present the device will self-oscillate. If this is
undesirable it may be prevented by connecting a 150k
between unused input and ground. This reduces the input
sensitivity by typically 50-100mV p-p.
7. The internal regulator has its input connected to Pin 8,
while the internal reference voltage appears at Pin 7 and
should be decoupled. For use from a 5.2V supply, Pins 7 and
8 should be connected together, and 5.2V applied to these
pins. For operation from supply voltages in the range +6.8V to
+9.5V, Pins 7 and 8 should be separately decoupled, and the
supply voltage applied to Pin 8.
100n
1n
V CC 1
MONITOR
SOURCE
SIGNAL
50
50
SP8789