VT1536A Isolated Digital Input/Output SCP 7
Input and Output Characteristics
This section describes the electrical characteristics of the SCP's input and
output sections, as well as the operation of the input debounce timers. Figure
4 shows a simplified schematic of one VT1536A channel.
Input Characteristics The input section drives an opto-isolator through a res istor thr eshold setting
network. Your system must provide at least 1 mA of current to drive the
opto-isolator. The threshold setting network contr ol s this drive current for
various input voltages ranging from 5 to 48 Volts (see Table 1 on page 5).
Your input voltage must be polarized positive to the Hnn terminal, and
negative to the Lnn terminal.
Output Characteristics The opto-isolated output provides a Solid-State relay and relay protection
voltage clamping diode. The solid state relay is non-polarized. The voltage
clamping diode limits voltage at the relay output to 80 VPEAK (begins to
conduct at about 60 VPEAK). The SS relay's on-resistance is 10 Ω,
off-resistance is at least 1010Ω. The relay's turn-on time is 3 milliseconds.
Figure 3 Recommended Connections and Voltage Limits