Microchip MIC2299-15YML Bedienungsanleitung


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MIC2299 Evaluation Board
3.5A I
SWMIN
, 2MHz, High Power LED
Driver w/ 3 Preset LED Current Settings
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
September 2007 M9999-092707-A
General Description
This board enables the evaluation of the 3.5A switch, High
Power white LED driver MIC2299. The board includes
components necessary to set the LED current to 20%,
50% and 100% of the nominal LED current (1A). The
external inputs also allow this to be programmed either
with additional resistors or voltages on the DIM or BRT
pins. A load disconnect switch prevents leakage and
protects the battery against short circuits while in
shutdown mode.
The evaluation board includes a push button switch which
sends a one shot pulse of 300ms to the enable pin to
prevent overheating when testing high power LEDs. Also
the enable pin can be driven to force the part into low Iq
mode.
The MIC2299, 2 MHz, Integrated Step-Up current
regulator, allows the use of small and very few external
components to create a compact boosted supply up to
13.5V with a core component footprint of just 0.25in
2
(1.61cm
2
). The evaluation board has been configured with
3 fixed current settings chosen using JP1 and all externally
programmable inputs are accessible via board pins.
Requirements
The MIC2299 evaluation board requires an input power
source that is able to deliver at least 5A over the desired
input voltage range. For the load, an electronic load (E-
Load) capable of constant voltage testing is required or a
high power LED mounted on a fan cooled heat sink. Note
that stability measurements must be carried out on an LED
load as E-Loads do not have the same dynamic
characteristics of a high power LED.
Precautions
The evaluation board does not have reverse polarity
protection. Applying a negative voltage to the VIN (J1)
terminal may damage the device.
The load current is only regulated if connected between
VOUT and FB terminals, the GND terminal close to the
VOUT terminal is provided for voltage measurements only.
The MIC2299 has a maximum input voltage rating of 10V
therefore the supply voltage should never exceed this
value.
Getting Started
1. Connect the input supply to the input terminals.
Take note of the polarity to prevent damage. An
ammeter can be used in-line with the VIN terminal
to measure input current. The Input voltage should
be measured at the input terminals to account for
any drops in test leads and amp meter.
2. Ensuring the jumper JP1 is at the left position
(50% load), connect the load to the output
terminals: +VO connects to the positive E-Load
input or Anode of the test LEDs, FB connects to
the negative E-Load input or the Cathode of the
test LEDs.
A low impedance ammeter can be connected in-
line with the +VO terminal for current
measurements. The output voltage should be
measured between the evaluation board terminals
+VO and GND (to measure converter efficiency) or
+VO and FB (to measure the voltage of the LED
load).
3. Switch on the E-Load (if using), then the input
supply. Measurements can now be taken of
efficiency, switching waveform and output current
regulation. When testing 1A load (JP1 open),
ensure that these are pulse tests only to prevent
damage to the LED. LED manufacturers
recommend <10% duty cycle and 3s period.
Ordering Information
Part Number Description
MIC2299-15YML EV Evaluation Board with MIC2299YML
15V OVP Device
Micrel, Inc. MIC2299 Evaluation Board
September 2007
2 M9999-092707-A
Evaluation Board
Board Description
By default, the board is set to give 500mA nominal current
into 2 series connected Power LEDs (JP1 at pre-FLSH
position). If the load is not present, the over voltage
protection (OVP) will limit V
OUT
to prevent damage to
output devices. JP1 can be removed to set the load
current higher to 1A (Flash) or moved to pins 1-2 to set a
lower 200mA current (Torch). Care should be taken as
removing the jumper sets the maximum current of 1A.
The push button switch is set to give a nominal 300ms
pulse to the load to prevent damage to external LEDs. For
testing continuous loading at lower currents, this mono-
stable can be bypassed by driving the EN terminal with a
voltage source above the enable threshold level.
The external pins can be driven to set any current between
the minimum and maximum values. See table. The
nominal current setting can be reduced by choosing a
larger value for R1 (current sense resistor). The 100%
current level can be set by using the following equation:
I
LED100%
= 0.2/R1
The values in the table will scale with the nominal 100%
current setting. So for example, if the 100% current is set
to 500mA, 0Ω on BRT will set LED current to 100mA,
50kΩ to 250mA etc.
DIM Voltage LED Current
RBRT = Open 40mA to 1A
0V to 200mV RBRT = GND 0 to 200mA
RBRT Voltage LED Current
0V to 1V 200mA to 1A
RBRT Resistance LED Current
0Ω to 100kΩ 200mA to 1A
Board Performance
High Power White LED Driver
50
60
70
80
90
100
2.5 3 3.5 4 4.5 5 5.5 6 6.5
SUPPLY VOLTAGE (V)
Efficiency VLED = 9V
I
LED
- 0.4A
I
LED
- 0.2A
-50
-40
-30
-20
-10
0
10
20
30
40
50
1 10 100 1000
FREQUENCY (kHz)
Bode Plot 2.2µH
(1A LED Load)
-180
-144
-108
-72
-36
36
72
108
144
180
Gain (3V
IN
)
Gain (4.2V
IN
)
Phase (3V
IN
)
Phase (4.2V
IN
)
Efficiency Stability 2.2µH Inductor
Micrel, Inc. MIC2299 Evaluation Board
September 2007
3 M9999-092707-A
0
100
200
300
400
500
600
700
800
900
1000
1100
DIM VOLTAGE (mV)
LED Current
vs. DIM Voltage
0 40 80 120 160 200
0
100
200
300
400
500
600
700
800
900
1000
1100
0 20 40 60 80 100 120 140
LED Current
vs. RBRT
V
IN
= 3.6V
LED Current Programming (VDIM) LED Current Programming (RBRT)
Switching Waveforms (BRT – GND) PWM Programming
0
50
100
150
200
250
0 20 40 60 80 100
DC (%)
LED Current
vs. DC (on EN Pin)
0
200
400
600
800
1000
1200
0 5 10 15 20 25 30 35
DC (%)
LED Current
vs. DC (on BRT Pin)
LED Current Programming
(100Hz PWM on Enable)
LED Current Programming
(1kHz PWM on BRT)


Produktspezifikationen

Marke: Microchip
Kategorie: Nicht kategorisiert
Modell: MIC2299-15YML

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