33874 Datasheet, PDF (28/37 Pages) Freescale Semiconductor, Inc – Quad High-Side Switch (Quad 35 mΩ)

TYPICAL APPLICATION
INTRODUCTION
TYPICAL APPLICATION
INTRODUCTION
The 33874 can be configured in several applications. The figure below shows the 33874 in a typical lighting application.
V_PWR
V_DD
Voltage regulator
V_DD V_PWR
V_DD
V_DD
10k 10k _100nF
V_DD
I/O
I/O
10k
I/O
Microcontroller
I/O
I/O
10k
10k
10k
SCLK
CS
I/O
10k
10k
10k
SO
10k
SI
A/D
A/D
10µF
1k
R1
V_DD
NC
WAKE
FS
IN0
IN1
IN2
IN3
SCLK
CS
RST
SI
SO
TEMP
CSNS
FSI
33874
GND
V_PWR
V_PWR
100nF
HS0
LOAD 0
21W 5 W
HS1
LOAD 1
21W 5 W
HS2
LOAD 2
21W 5 W
HS3
LOAD 3
21W 5 W
Automotive lamps do not tolerate high voltages very well. Tests of a few lamps indicate that failures can occur when
18V is applied for a few seconds. Consequently, PWM switching reduces the effective RMS voltage in order to drive
bulbs safety.
For example, to maintain the power dissipation associated with a 13V battery at 100% duty cycle, the duty cycle
would be adjusted to (13/18)², or 52%, when the battery is at 18V.
The loads must be chosen in order to guarantee the device normal operating condition as junction temperature
from -40 to 150 °C. In case of permanent short-circuit conditions, the duration and number of activation cycles must
be limited with a dedicated MCU fault management using the fault reporting through SPI.
33874
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Analog Integrated Circuit Device Data
Freescale Semiconductor