SP8660 Plessey Semiconductors, SP8660 Datasheet - Page 4

• Manufacturer Part Number: SP8660
• Description: Low Power ECL Counter
• Manufacturer: Plessey Semiconductors

OPERATING NOTES
1.The clock inputs (pins 1 and 8) should be capacitively coupled
to the signal source. When driven single ended, the input signal
path is completed by a capacitor from the unused input to ground.
2. In the absence of a signal the devices will self-oscillate. This can
be prevented by connecting a 39k
ground. If the device is driven single ended, it is recommended
that the pull-down resistor be connected to the decoupled unused
input. There will be a loss in sensitivity of approximately 200mV.
3. The device will operate down to DC but input slew rate must be
better than 100V/ s.
4. The open collector output will drive three TTL loads, and
therefore requires a a suitable resistor to V
immunity. In order to maintain noise immunity on transitions, this
TO SAMPLING
INPUT
GENERATOR
39k
SCOPE
FROM
1n
1n
Fig. 7. Interfacing to TTL. Load not to exceed 3 TTL unit loads
resistor from either input to
1
8
Fig. 6. Typical application circuit showing interfacing
CC
1·6k
to maintain noise
1n
SP8660
1n
2
1
8
10n
Fig. 5 Test circuit
1n
1·6k
4
DUT
BIAS
2
5
V
CC
DIVIDE BY
5
2
2·2k
resistor should not exceed 4·7k . For interfacing to CMOS, the
open collector may be restored to a 110V line via a 3·3k resistor.
The output sink current must not exceed 10mA and the use of too
low a value of resistor may lead to a loss of noise immunity,
especially at low temperatures.
5. Input impedance varies as a function of frequency; see Fig. 4.
6. The rise time of the open collector output waveform is directly
proportional to the load capacitance and load resistor value.
Therefore, the load capacitance should be minimised and the
load resistor kept to a minimum compatible with system power
requirements.
approximately 20ns and the fall time is typically 10ns.
15V
4
10
In the test configuration of Fig. 5, the output rise time is
3·3k
110V
TTL
7p
1k
15V
100n
4
15V/110V
SAMPLING
3·3k
SCOPE
CMOS SUPPLY VOLTAGE)
INPUT
(DEPENDING ON
CMOS
SP8660
3