s Overview
The AN8353UB is a dimmer IC to control illumination of the car dashboard at high efficiency and high performance by pul width control. It outputs puls at a duty proprotional to an input voltage.
s Features
•Low power consumption by pul control
鬼的英文•External ON/OFF control by the standby pin •Pul frequency range : 50Hz to 10kHz
•Built-in overvoltage protective circuit approx. 20V
•Wide operating ambient temperature range : –40˚C to+100˚C •All products temperature cycle, high reliability by normal
and high temperature checks reliability equivalent to the air bags requested in U.S.
AN8353UBthrice
High Efficiency Car Dashboard Dimmer IC
s Block Diagram
Pin No.Pin name
s Pin Descriptions
Description
1Output pin Outputs an intermittent source current at a duty proportional to an input voltage
2GND GND开车转弯技巧
3Input pin
Applies a control voltage.
4Noi eliminating capacity connection pin 1Connect a capacitor to eliminator a noi.
7Noi eliminating capacity connection pin 2Connect a capacitor to eliminator a noi.wangzhi
9
V CC
Supply Voltage
5Square wave output pin 6Triangular wave output pin 8Standby pin Output a triangular wave, which rves as a reference for the PWM signal, to the Pin6 by connecting the resistor R T between the Pins5 and6, and capacity C T between the Pin6 and GND.
Output a triangular wave, which rves as a reference for the PWM signal, to this pin by connecting the resistor R T between the Pins6 and 5, and capasity C T between the Pin6 and GND.Forces to shut off an output current if a voltage higher than a threshold voltage of 1.1V is applied to the Pin8.V CC P D T opr T stg
Supply voltage Power dissipation Storage temperature
Operating ambient temperature
V mW ˚C ˚C
Parameter
Symbol Rating Unit s Absolute Maximum Ratings (Ta=25˚C)
22550–40 to +100–50 to +150
medusa
Parameter
国庆节英语怎么说Symbol Range s Recommended Operating Range (Ta=25˚C)
Operating supply voltage range
V CC
aobi8 to 18V
Parameter
Symbol Condition
min
typ max s Electrical Characteristics (Ta=25˚C)
Supply current I CC 11mA 7.5Eliminate C T and R T Oscillation frequency f osc Hz 115C T =0.027µF 0% duty input voltage V IN – 03V 2.5C T =0.027µF 100% duty input voltage V IN– 100V C T =0.027µF Center duty (V CC =12V)D 12V %45C T =0.027µF %C T =0.027µF Center duty (V CC =8V)DD 8V %0C T =0.027µF 10Center duty (V CC =18V)DD 18V %50C T =0.027µF Output duty gain D G V Output voltage at ON V ON µA 0C T =2100pF Leakage current at OFF I L V 20C T =2100pF 221.65
4551.210.5140551118450.6
49029.535–1–1Over voltage detection voltage V OV C T =2100pF V
1.1
C T =2100pF
Standby threshold voltage
V STH
00.90.55Unit
• Bipolar Transister Output
• MOS FET Output
s Application Circuit
s Supplementary Description
• System Operational Principle
The following describes the operational principle of the system using the AN8353UB.
As shown in the block diagram in Fig. 1, a battery voltage is divided by the VR and input to the input Pin3 in accord-ance with rotation amount. The voltage at the output Pin1 is controlled by the AN8353UB so that the duty of the ON/OFF period of the external output transistor will be proportional to the input voltage, thus controlling a current flowing to the lamps of the dashboard, etc. to adjust their brightness. Since the output transistors are saturated at ON time and no current flows at OFF time, power consumption is low.
The PWM method is ud to control the output transistors. This method, as shown in Fig. 2 I/O Characteristic Chart (III), generates the triangular wave V 6 as a reference signal
平面设计学徒
to generate puls and input them to one end (Pin6) of the PWM comparator. The triangular wave frequency f OSC can be freely t from 50Hz to 10kHz, depending on the resistance value R T connected between the square wave output Pin5 and triangular wave output Pin6, and capacity valu
e C T connected between the triangular wave output Pin6 and ground Pin2. The approximating expression for the then PWM frequency f OSC is ;
1/f OSC =1.705C T R T ······················································(1) For your refence, Fig. 3 shows the relations among C T , R T , and oscillation frequency f OSC . The voltage V 4, who voltage level is made matching the amplitude of the triangular wave by the control voltage converter, is given to the other input (Pin4) of the PWM comparator. That is, in Fig. 2 (II), the input voltage V 3 is linearly converted into V 4 by the control voltage converter so that the amplitude of the triangular wave will be about 20% to 80% of the input voltage input range (axis of abscissas in Fig. 2 (II)).北京留学网
Then, a current is supplied from the output Pin1 to turn on the output transistors during the period (T ON ) when the inverted input voltage is larger than the triangular wave. (Fig. 2 (II), (IV)) To the contra
ry, while the converted input voltage is smaller than the triangular wave, no current is supplied from the output Pin1 and the output transistors are turned off. The output pul duty is expresd as follows.
Duty=T ON · f OSC ······················································(2) For the duty control characteristic of the output puls to the input voltage V 3, the duty of the output puls is controlled from 0% to 100% at high-precision linearity while the “input voltage V 3/supply voltage V 9” is between about
Fig. 1 AN8353UB Block Diagram
0.2 (B-point) and 0.8 (C-point). The A-point in the figure shows the I/O characteristics when the “input voltage V 3/sup-ply voltage V 9” is 0.7. And, when V 3/V 9 is from 0.05V to about 0.2V (B-point), the duty is controlled to 0%, and when V 3/V 9 is from 0.8V (C-point) to t.0V, the duty is controlled to 100%.
The standby Pin8 can forcibly turn off the output transistors by applying a voltage of about 1.1V or more to this pin. When it is not necessary to forcibly turn off the output tran-sistors, Leave the standby Pin8 open.
• System Operational Principle (cont.)
• Over voltage Detecting Voltage vs. Output
s Supplementary Description (cont.)
D V 9–2
V OV
50%
0%
• Standby Threshold Voltage vs. Output
• Duty D 1 vs. Input Voltage V IN
D 8–2
V STH
50%
D V IN
V V Fig. 2 I/O Characteristic Chart
Fig. 3 Relations between Oscillation Frequency and C T and R T
IN–0
IN–100
D · Output voltage at ON V ON · Leakage current at OFF
V ON =V CC –V 1–2
I L =V 1–2
IM Ω
0%Resistance R T (Ω)
1M
O s c i l l a t i o n F r e q u e n c y f O S C (H z )
100k
10k
1k
100
10emb
