sp646 Solid State Optronic, sp646 Datasheet - Page 3

• Manufacturer Part Number: sp646
• Description: 1 Form A Solid State Relay
• Manufacturer: Solid State Optronic

ZERO-VOLT SWITCHING
Figure 1 shows the sequence of zero-volt switching operation. At Stage 1, an input signal is applied to the relay. The relay will not turn on
until the threshold voltage of 5V is reached. Once this point is reached (Stage 2), SCR #1 (designated as the SCR which controls positive
AC voltage) turns on. However, SCR #1 only conducts for an instant, as the cycle quickly crosses zero. At this point (Stage 3), SCR #1 will
turn off and SCR #2 (negative AC voltage) turns on. Likewise, at the next zero cross (Stage 4), SCR #2 will turn off and SCR #1 conducts
again. Even though the input signal is terminated at Stage 5, the relay will continue to conduct (typical SCR behavior) until Stage 6, when
SCR #1 crosses zero and ceases to conduct. Please note that turn on can likewise begin on the negative phase of the AC cycle with a -5V
threshold, though only the positive phase is shown here.
PERFORMANCE DATA
This solid state relay has been designed with a driver circuit that controls the operation of two back-to-back silicon controlled rectifiers
(SCRs), each responsible for one half of the AC cycle. If an AC signal is examined, the turn on, turn off and zero-volt switching can be seen.
Figure 1 shows a typical 60 Hz, 120Vac signal with a corresponding relay input signal:
© 2004 Solid State Optronics • San José, CA
www.ssousa.com • +1.408.293.4600
1500
1000
500
0
Threshold
Maximum Load Current vs. Temperature
-40
Input Signal
5 V
-20
Tem perature (C)
0
SP646
20
40
1
3
Relay Input Signal is
Turned On.
SCR #1 Turns Off,
SCR #2 Turns On
at Zero Volts.
60
80
2
Page 3 of 5
SCR #1 Turns On when
5V threshold is reached.
60
50
40
30
20
10
0
425 450 475 500 525 550 575 600
4
N = 100, Ambient Temperature = 25°C
Typical Blocking Voltage Distribution
SCR #2 Turns Off,
SCR #1 Turns On
at Zero Volts.
Blocking Voltage (V)
5
SP646
Relay Input Signal is
Turned Off.
6
SCR #1 and Relay Turn
Off at Zero Volts.
SP646
Solid State Relay
rev 1.40 (10/25/2004)
1 Form A
SP646