ISL71841SEH Datasheet, PDF (24/29 Pages) Intersil Corporation – Radiation Hardened 30V 32-Channel Analog

ISL71841SEH
Applications Information
Power-Up Considerations
The circuit is designed to be insensitive to any given power-up
sequence between V⁺, V^- and VREF, however, it is recommended
that all supplies power-up relatively close to each other.
Overvoltage Protection
The ISL71841SEH has overvoltage protection on both the input
as well as the output. On the output, the voltage is limited to a
diode past the rails. Each of the inputs has independent
overvoltage protection that works regardless of the switch being
selected. If a switch experiences an overvoltage condition (3V to
4V past the rail), the switch is turned off. As soon as the voltage
returns within the rails, the switch returns to normal operation.
VREF and Logic Functionality
The VREF pin sets the logic threshold for the ISL71841SEH. The
range for VREF is between 4.5V and 5.5V with a nominal voltage
of 5V. The address pins and enable are compared against
roughly 30% of V_REF voltage (refer to Figure 79). With 5.0V on
V_REF, the switching point is set to around 1.4V. This switching
point allows for both 5V and 3.3V logic control.
ISL71841SEH vs ISL71840SEH
There is a 16-channel version of the ISL71841SEH available in a
28 Ld CDFP. In terms of performance specs, the parts are very
similar in behavior. Apart from the apparent increase in channel
density, the ISL71841SEH does have slightly higher output
leakage compared to the ISL71840SEH due to having more
channels connected to the output. The supply current for the
ISL71841SEH is also a bit higher compared to the ISL71840SEH.
(See Table 1 on page 3.)
A/EN
VREF
ISL71841SEH
400kΩ
TO DECODER
200kΩ
FIGURE 79. SIMPLIFIED V_REF CIRCUITRY
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FN8735.4
June 3, 2016