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PDF MAQ3203 Data sheet ( Hoja de datos )
| Número de pieza | MAQ3203 | |
| Descripción | High-Brightness LED Driver Controller | |
| Fabricantes | Micrel Semiconductor | |
| Logotipo |  |
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MAQ3203
High-Brightness LED Driver Controller
with High-Side Current Sense
General Description
The MAQ3203 is a hysteretic, step-down, constant-
current, High-Brightness LED (HB LED) driver. It provides
an ideal solution for interior/exterior lighting, architectural
and ambient lighting, LED bulbs, and other general
illumination applications.
The MAQ3203 is well suited for lighting applications
requiring a wide-input voltage range. The hysteretic control
gives good supply rejection and fast response during load
transients and PWM dimming. The high-side current
sensing and on-chip current-sense amplifier delivers LED
current with ±5% accuracy. An external high-side current-
sense resistor is used to set the output current.
The MAQ3203 offers a dedicated PWM input (DIM) which
enables a wide range of pulsed dimming. A high-frequency
switching operation up to 1.5MHz allows the use of smaller
external components minimizing space and cost. The
MAQ3203 offers frequency dither feature for EMI control.
The MAQ3203 operates over a junction temperature from
−40°C to +125°C and is available in an 8-pin SOIC
package. The MAQ3203 is AEC-Q100 qualified for
automotive applications.
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Features
• AEC-Q100 qualified
• 4.5V to 42V input voltage range
• High efficiency (>90%)
• ±5% LED current accuracy
• Dither enabled for low EMI
• High-side current sense
• Dedicated dimming control input
• Hysteretic control (no compensation!)
• Up to 1.5MHz switching frequency
• Adjustable constant LED current
• Over-temperature protection
• −40°C to +125°C junction temperature range
Applications
• Automotive lighting
• Industrial lighting
Typical Application
MAQ3203 Step-Down LED Driver
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
April 20, 2015
Revision 1.2
1 page  
Micrel, Inc.
Typical Characteristics
Efficiency
vs Input Voltage
100
90
4LED
6LED
80
8LED
10LED
70
60
0
L=150µH
ILED=1A
5 10 15 20 25 30 35 40 45
INPUT VOLTAGE (V)
Efficiency
vs Input Voltage
100
90
80
70
60
0
4LED
6LED
8LED
10LED
L=68µH
ILED=1A
5 10 15 20 25 30 35 40 45
INPUT VOLTAGE (V)
MAQ3203
Normalized LED Currents
vs Input Voltage
1.03
1.02
1.01
4LED 6LED
1LED 2LED
1
10LED
8LED
0.99
0.98
0.97
0
L=150µH
ILED=1A
5 10 15 20 25 30 35 40 45
INPUT VOLTAGE (V)
Normalized LED Currents
vs. Input Voltage
1.03
1.02
L=68µH
ILED=1A
1.01
1
0.99
0.98
1LED
2LED
4LED
6LED 8LED
10LED
0.97
0
5 10 15 20 25 30 35 40 45
INPUT VOLTAGE (V)
Frequency
vs. Input Voltage
350
300 L=150µH
ILED=1A
250
200
4LED
150 2LED
100
50
0
0
1LED
6LED
10LED
8LED
5 10 15 20 25 30 35 40
INPUT VOLTAGE (V)
45
Frequency
vs. Input Voltage
700
600 L=68µH
ILED=1A
500 4LED
400
2LED
300
200 1LED
100
0
0
6LED 8LED 10LED
5 10 15 20 25 30 35 40 45
INPUT VOLTAGE (V)
Duty Cycle
vs. Input Voltage
100
75
1LED
50
2LED
10LED
4LED
8LED
6LED
25
L=150µH
ILED=1A
0
0 5 10 15 20 25 30 35 40 45
INPUT VOLTAGE (V)
Duty Cycle
vs Input Voltage
100
75
1LED
50
2LED
4LED
10LED
8LED
6LED
25
L=68µH
ILED=1A
0
0 5 10 15 20 25 30 35 40 45
INPUT VOLTAGE (V)
Supply Current
vs. Input Voltage
1.4
1.2
1.0 TA = 25°C
ILED = 0A
0.8
0.6
0.4
0.2
0.0
0
5 10 15 20 25 30 35 40 45
INPUT VOLTAGE (V)
April 20, 2015 5 Revision 1.2
5 Page 
Micrel, Inc.
Application Information
The internal block diagram of the MAQ3203 is shown in
the Functional Diagram. The MAQ3203 is composed of a
current-sense comparator, voltage and current reference,
5V regulator and MOSFET driver. Hysteretic mode
control – also called bang-bang control – is a topology
that does not employ an error amplifier, using an error
comparator instead.
The inductor current is controlled within a hysteretic
window. If the inductor current is too small, the power
MOSFET is turned on; if the inductor current is large
enough, the power MOSFET is turned off. It is a simple
control scheme with no oscillator and no loop
compensation. Since the control scheme does not need
loop compensation, it makes a design easy, and avoids
problems of instability.
Transient response to load and line variation is very fast
and only depends on propagation delay. This makes the
control scheme very popular for certain applications.
LED Current and RCS
The main feature in MAQ3203 is to control the LED
current accurately within ±5% of set current. Choosing a
high-side RCS resistor helps for setting constant LED
current irrespective of wide input voltage range. Equation
1 gives the RCS value:
RCS
=
1
2
x( VCS(MAX) + VCS(MIN)
ILED
)
Eq. 1
Table 1. RCS for LED Current
RCS (Ω)
ILED (A)
1.33 0.15
0.56 0.35
0.4 0.5
0.28 0.7
0.2 1.0
0.13 1.5
0.1 2.0
0.08 2.5
0.068
3.0
I2R (W)
0.03
0.07
0.1
0.137
0.2
0.3
0.4
0.5
0.6
Size (SMD)
0603
0805
0805
0805
1206
1206
2010
2010
2010
For VCS(MAX) and VCS(MIN), refer to the Electrical
Characteristics section.
MAQ3203
Frequency of Operation
Refer to Equation 2 to calculate the frequency spread
across input supply.
VL
=L
ΔIL
Δt
Eq. 2
L is the inductance; ∆IL is fixed (the value of the
hysteresis):
∆IL
=
VCS(MAX) - VCS(MIN)
R CS
Eq. 3
VL is the voltage across inductor L which varies by
supply.
For current rising (MOSFET is ON):
tr
=L
∆IL
VL _ RISE
Eq. 4
where:
VL_RISE = VIN − ILED × RCS − VLED
For current falling (MOSFET is OFF):
tf
= L ∆IL
VL _ FALL
Eq. 5
where:
VL_FALL = VD + ILED × RCS + VLED
1
T = tr + tf , FSW = T
FSW
=
(VD
+ ILED × RCS + VLED ) × (VIN - ILED × RCS
L × ΔIL × (VD + VIN)
- VLED )
where :
• VD is Schottky diode forward drop
• VLED is total LEDs voltage drop
• VIN is input voltage
• ILED is average LED current
April 20, 2015 11 Revision 1.2
11 Page | ||
| Páginas | Total 23 Páginas | |
| PDF Descargar | [ Datasheet MAQ3203.PDF ] | |
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