Rainbow Electronics MAX13362 - Manual (Page 13)

Any switch position change (if the switch is interrupt-
enabled) is signaled through the active-low open-drain
INT output. The INT output is cleared when CS goes
low.
Shutdown Mode
In shutdown mode, all switch inputs are high imped-
ance and the external switches are no longer moni-
tored, reducing current consumption on VS to 6µA
(typ). The IC resets upon entering shutdown mode and
the contents of the command registers are lost.
Therefore, any setting other than power-on-reset
defaults needs to be reprogrammed after exiting from
the shutdown mode.
Applications Information
Overtemperature Protection
If the IC junction temperature exceeds +165°C, an
interrupt signal is generated and the wetting currents
are disabled to reduce the on-chip power dissipation.
During an overtemperature event, the last switch status
is retained in internal memory and the switch status is
not updated. The interrupt output is cleared when
CS
goes high, but the overtemperature bit T in the output
word remains for as long as the overtemperature condi-
tion persists. When the junction temperature drops by
15°C, the wetting currents are re-enabled and there is a
1ms blanking time before the switches can be polled.
Reverse-Battery Tolerance
The IN0–IN23 switch inputs withstand up to -15V DC
voltage without damage. A reverse-battery diode is
needed to protect VS as shown in the
Typical
Application Circuit . SD can be controlled from a bat-
tery-level source but should be protected against
reverse battery in the application.
Wetting Current and Power Dissipation
The maximum power dissipation happens when all
switch inputs configured with 15mA continuous wetting
current are all closed. Assuming the battery voltage is
14V, the corresponding power dissipated by the IC is
24 x 14V x 15mA = 5040mW. This exceeds the
absolute maximum power dissipation of 2963mW. In
polling mode, the wetting currents are pulsed at the
programmed polling time to reduce the total power dis-
sipated in the IC.
ISO 7637 Pulse Immunity
VS, SD, and IN0–IN23 are potentially exposed to ISO
7637 pulses. Bypass VS with a 0.1µF and a 47µF
capacitor. The VS and
SD voltage must be limited
below 40V during load dump. Bypass IN0–IN23 with at
least 0.047µF capacitors at the ECU connector. When
IN0–IN3 or IN23 inputs are used with battery-connected
switches, a 100Ω series resistor is needed. These
external components allow VS,
SD, and IN0–IN23 to
withstand ISO 7637 pulses in the application circuit.
Mechanical Switch Characteristics
The MAX13362 is designed to operate with switches
that have the following characteristics:
1) Minimum resistance value with switch open (due to
leakage): 10kΩ.
2) Maximum resistance value with switch closed:
100Ω.
Chip Information
PROCESS: BiCMOS
MAX13362
24-Channel Automotive Switch Monitor
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