MC33193D Просмотр технического описания (PDF) - Motorola => Freescale
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MC33193D Datasheet PDF : 8 Pages
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Freescale SMeCm3i3c1o93nductor, Inc.
Figure 1. Normal Operation Oscillator
Timing Diagram
Figure 2. One Defective Lamp Oscillator
Timing Diagram
0
– 1.0
– 2.0
– 3.0
– 4.0
t1
“On” “Off”
tn
Fn = 1/tn
0
– 1.0
– 2.0
“On” “Off”
– 3.0
– 4.0
tf
Ft = 1/tf
TIME
TIME
INTRODUCTION
The MC33193 is designed to drive the direction indicator
flasher relay. It is a new generation industry standard
UAA1041 “Flasher”. It consists of the following functions:
• Supply and Protections
• On–Chip Relay Driver
• Oscillator
• Starter Functions
• Lamp Fault Detector with Internal RF Filter
• Standby Mode
Supply and Protection Systems
Pin 1 is connected to ground via resistor R3 which limits
the current in the event of any high voltage transients. Pin 2
(VCC) is the positive supply and may be connected directly to
the vehicle’s battery voltage.
Overvoltage and Double Battery Protection: When the
applied VCC to VSS voltage is greater than 22 V, the
overvoltage detector circuit turns the relay driver off. Both the
device and the lamps are protected if two 12 V batteries are
connected in series and used to jump start the vehicle.
Load Dump Overvoltage Protection: A 29 V overvoltage
detector protects the circuits against high voltage transients
due to load dumps and other low energy spikes. The relay
driver is automatically turned on whenever the VCC to VSS
voltage is greater than 34 V.
Overvoltage Protection, High Voltage Transients: The
Enable and the Starter pins are protected against positive
and negative transients by internal on–chip diodes.
On–Chip Relay Driver
The device directly drives the flasher relay. The output
structure is an Emitter of an NPN transistor. It contains the
free wheeling diode circuitry necessary to protect the device
whenever the relay is switched off.
Oscillator
The device uses a sawtooth oscillator (Figure 1).
The frequency is determined by the external components
C1 and R1. In the normal operating mode, the flashing
frequency is: Fn = 1/R1*C1*Kn. With a defective (open) 21 W
lamp (Figure 2), the flashing frequency changes to: Fn =
2.2*Fn.
The typical first flash delay (the time between the moment
when the indicator switch is closed and the first lamp flash
occurs) is: t1 = K1*R1*C1
The fault detection delay is from the time relay R1 is on
and fault detection is enabled. Where a 21 W lamp opens, the
delay is expressed as: t2 = K2*R1*C1
Starter
Pin 8 is connected through a 3.3 kΩ resistor to the flashing
lamp. Pin 8 is the input to the Starter function and senses the
use of S1 by sensing ground through the lamp (Figures 9 and
10).
Lamp Fault Detector with Internal RF Filter
A Lamp defect is sensed by the lamp fault detector’s
monitoring of the voltage developed across the external
shunt resistor RS via the RF filter. The RS voltage drop is
compared to a Vbat dependent internal reference voltage
(Vref) to validate the comparison over the full battery voltage
range. A detected fault causes the oscillator to change
frequency (Figure 2).
Standby Mode
When the ignition key and warning switches are open;
Enable is in a low state and the internal switches, SW1 and
SW2, are open and no current passes through the circuit. In
this condition, the device’s current consumption is zero
(ICC = 0). When ignition key and warning switches are
closed; Enable is in a high state with SW1 and SW2 being
closed and the circuit is powered on.
MOTOROLA ANALOG IC DEVICEFDoArTAMore Information On This Product,
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