Instrukcja obsługi Microchip MIC4802YME
Microchip
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MIC4802YME
Przeczytaj poniżej 📖 instrukcję obsługi w języku polskim dla Microchip MIC4802YME (4 stron) w kategorii nieskategoryzowany. Ta instrukcja była pomocna dla 6 osób i została oceniona przez 3.5 użytkowników na średnio 4.4 gwiazdek
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MIC4802 Evaluation Board
High Efficiency 800mA Single Channel
Linear WLED Driver with
Ultra Fast PWM™ Control
Ultra Fast PWM is a trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
General Description
The MIC4802 is a high efficiency, single channel, White
LED (WLED) driver. This constant current linear device is
designed to drive a single high power WLED up to 800mA
and features a low dropout of 280mV at 800mA (typical).
Brightness is controlled through an Ultra Fast PWM™
interface which can operate from 1% to 100% duty cycle.
The MIC4802 is available in an 8-pin Epad SOIC leaded
package with a junction temperature range of -40°C to
+125°C
Requirements
The MIC4802 evaluation board requires a power supply
that is capable of delivering at least 1A while providing an
input voltage between 3.0V and 5.5V.
Precautions
The MIC4802 evaluation board is designed for an input
voltage no greater than 6V. This evaluation board does not
have reverse polarity protection; hence, applying a
negative voltage to the VIN terminal may damage the
device.
Getting Started
1. Connect an external supply to V IN. Apply the
desired input voltage across VIN and ground
terminals, J2 and J3, respectively, paying careful
attention to polarity and supply voltage
(3.0VVIN5.5V). An ammeter may be placed
between the input supply and the V IN terminal to
the evaluation board. Ensure that the supply
voltage is monitored at the VIN terminal. The
ammeter and/or power lead resistance can reduce
the voltage supplied to the input. VBAT is
connected to VIN through a 0 resistor, R1.
March 2011 M9999-032111-B
2. Enable/Disable the MIC4802
To enable the device, apply a DC voltage of 1.2V or
greater to the EN pin. This allows for full brightness of
the WLED(s) (100% duty cycle). The EN pin can also
be used for dimming by connecting a PWM signal and
varying its duty cycle (please refer to the Ultra Fast
PWM™ Dimming Interface section in the datasheet).
Pulling EN low for more than 40ms forces the
MIC4802 into a low IQ sleep mode. Do not leave the
EN pin floating as this may cause an indeterminate output
state. A pull up resistor of 10k is placed from EN (JP1)
to VIN to ensure that the WLED is ON when an input signal
is applied.
3. Setting LED current with RSET resistor.
The average LED current may be calculated using the
equation below:
( )
280.0)(
4920
)(
280.0
)(
4920
)(
−Ω
⋅
=
+
⋅
=Ω
kR
D
mAI
mAI
D
kR
SET
LED
LED
SET
D is the duty cycle of the LED current during PWM
dimming; D=1 when device is fully ON. The stock
evaluation board uses an RSET value of 6.19k which
corresponds to ILED of 830mA.
4. Measuring WLED current.
To measure WLED current, simply insert an ammeter
in series with the WLED(s). Keep in mind that a series
ammeter will add a small voltage drop, so the voltage
at the WLED terminal, D1, should be used when
making dropout measurements with a series ammeter.
Ordering Information
Part Number Description
MIC4802YME EV Evaluation board with the Single
Channel MIC4802 device
Specyfikacje produktu
| Marka: | Microchip |
| Kategoria: | nieskategoryzowany |
| Model: | MIC4802YME |
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