ISL71840SEH Datasheet, PDF (23/27 Pages) Intersil Corporation – Radiation Hardened 30V 16-Channel Analog

ISL71840SEH
Post Low Dose Rate Radiation Characteristics (V± = ±12V) Unless otherwise
specified, V± = ±12V, V_CM = 0,V_O = 0V, T_A = +25°C. This data is typical mean test data post radiation exposure at a low dose rate of <10mrad(Si)/s. This
data is intended to show typical parameter shifts due to low dose rate radiation. These are not limits nor are they guaranteed. (Continued)
25
20
BIASED
15
10
5
0
GROUNDED
-5
-10
0
10
20
30
40
50
60
LOW DOSE RATE RADIATION (krad(Si))
FIGURE 77. t_ENABLE SHIFT vs LDR RADIATION
300
BIASED
250
200
GROUNDED
150
100
50
0
0
10
20
30
40
50
60
LOW DOSE RATE RADIATION (krad(Si))
FIGURE 78. t_DISABLE SHIFT vs LDR RADIATION
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 ISL71840SEH 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 ISL71840SEH. 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 5V on V_REF,
the switching point is set to around 1.4V. This switching point
allows for both 5V and 3.3V logic control.
ISL71840SEH vs ISL71841SEH
There is a 32-channel version of the ISL71840SEH available in a
48 Ld CQFP. 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).
ISL71840SEH
A/EN
VREF
400kΩ
TO DECODER
200kΩ
FIGURE 79. SIMPLIFIED VREF CIRCUITRY
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FN8734.3
June 9, 2016