SI8220 SILABS [Silicon Laboratories], SI8220 Datasheet - Page 17

• Manufacturer Part Number: SI8220
• Description: 0.5 AND 2.5 AMP ISODRIVERS WITH OPTO INPUT (2.5, 3.75, AND 5.0 KVRMS)
• Manufacturer: SILABS [Silicon Laboratories]

6.5. Parametric Differences between Si8220/21 and
The Si8220/21 is designed to directly replace HCPL-3120 and similar opto drivers. Parametric differences are
summarized in Table 10 below.
6.5.1. Supply Voltage and UVLO
The supply voltage of the Si8220/21 is limited to 24 V, and the UVLO voltage thresholds are scaled accordingly.
This will not be an issue for opto replacement applications operating with supply voltages of 24 V and below.
6.5.2. Input Diode Differences
The Si8220/21 input circuit requires less current and has twice the off-state noise margin compared to opto drivers.
However, high CMR opto driver designs that overdrive the LED (see Figure 14) may require increasing the value of
R1 to limit input current to 10 mA max. In addition, there is no benefit in driving the Si8220/21 input diode into
reverse bias when in the off state. Consequently, opto driver circuits using this technique should either leave the
negative bias circuitry unpopulated or modify the circuitry (e.g. add a clamp diode) to ensure that the anode pin of
the Si8220/21 is no more than -0.8 V with respect to the cathode when reverse-biased.
HCPL-0302 and HCPL-3120 Opto Drivers
Max supply voltage
ON state forward input current
OFF state input voltage
Max reverse input voltage
UVLO threshold (rising)
UVLO threshold (falling)
UVLO hysteresis
Rise/fall time into 10  in series with 10 nF
Max supply voltage
ON state forward input current
OFF state input voltage
Max reverse input voltage
UVLO threshold (rising)
UVLO threshold (falling)
UVLO hysteresis
Rise/fall time into 10  in series with 10 nF
Table 10. Parametric Differences of Si8220 vs. HCPL-3120
Table 11. Parametric Differences of Si8221 vs. HCPL-0302
Parameter
Parameter
Rev. 0.22
–0.6 to +1.6
–0.6 to +1.6
5.8 to 13.8
5.5 to 12.8
5.8 to 13.8
5.5 to 12.8
0.28 to 1
0.28 to 1
Si8220
Si8221
5 to 20
5 to 20
0.5
0.5
24
20
24
20
–0.3 to +0.8
–0.3 to +0.8
HCPL-3120
11.0 to 13.5
HCPL-0302
11.0 to 13.5
9.7 to 12.0
9.7 to 12.0
7 to 16
7 to 16
100
100
1.6
1.6
30
–5
30
–5
Si8220/21
Units
Units
mA
mA
ns
ns
V
V
V
V
V
V
V
V
V
V
V
V
17