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PDF MAX16834 Data sheet ( Hoja de datos )
| Número de pieza | MAX16834 | |
| Descripción | High-Power LED Driver | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MAX16834 (archivo pdf) en la parte inferior de esta página. Total 23 Páginas | ||
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EVALUATION KIT AVAILABLE
MAX16834
High-Power LED Driver with Integrated
High-Side LED Current Sense and
PWM Dimming MOSFET Driver
General Description
The MAX16834 is a current-mode high-brightness LED
(HB LED) driver for boost, boost-buck, SEPIC, and high-
side buck topologies. In addition to driving an n-channel
power MOSFET switch controlled by the switching con-
troller, it also drives an n-channel PWM dimming switch to
achieve LED PWM dimming. The MAX16834 integrates
all the building blocks necessary to implement a fixed-fre-
quency HB LED driver with wide-range dimming control.
The MAX16834 features constant-frequency peak cur-
rent-mode control with programmable slope compensa-
tion to control the duty cycle of the PWM controller.
A dimming driver designed to drive an external n-chan-
nel MOSFET in series with the LED string provides
wide-range dimming control up to 20kHz. In addition to
PWM dimming, the MAX16834 provides analog dim-
ming using a DC input at REFI. The programmable
switching frequency (100kHz to 1MHz) allows design
optimization for efficiency and board space reduction.
A single resistor from RT/SYNC to ground sets the
switching frequency from 100kHz to 1MHz while an
external clock signal at RT/SYNC disables the internal
oscillator and allows the MAX16834 to synchronize to
an external clock. The MAX16834’s integrated high-
side current-sense amplifier eliminates the need for a
separate high-side LED current-sense amplifier in
boost-buck applications.
The MAX16834 operates over a wide supply range of
4.75V to 28V and includes a 3A sink/source gate driver
for driving a power MOSFET in high-power LED driver
applications. It can also operate at input voltages
greater than 28V in boost configuration with an external
voltage clamp. The MAX16834 is also suitable for DC-
DC converter applications such as boost or boost-
buck. Additional features include external enable/
disable input, an on-chip oscillator, fault indicator out-
put (FLT) for LED open/short or overtemperature condi-
tions, and an overvoltage protection sense input
(OVP+) for true overvoltage protection.
The MAX16834 is available in a thermally enhanced
4mm x 4mm, 20-pin TQFN-EP package and in a thermal-
ly enhanced 20-pin TSSOP-EP package and is specified
over the automotive -40°C to +125°C temperature range.
Applications
• Single-String LED LCD Backlighting
• Automotive Rear and Front Lighting
• Projection System RGB LED Light Sources
• Architectural and Decorative Lighting (MR16, M111)
• Spot and Ambient Lights
• DC-DC Boost/Boost-Buck Converters
Benefits and Features
• Integration Minimizes BOM for High-Brightness LED
Driver with a Wide Dimming Range Saving Space
and Cost
• Constant-Frequency, Peak Current-Mode Control
with Programmable Slope Compensation
• Integrated PWM Dimming MOSFET Driver
• 3000:1 PWM Dimming/Analog Dimming
• Integrated High-Side Current-Sense Amplifier for
LED Current Sense in Boost-Buck Converter
• Internal 7V Low-Dropout Regulator
• Simple Optimization for Efficiency, Board Space and
Input Operating Range
• Supports Boost, Buck-Boost, SEPIC, and High-
Side Buck Topologies
• 100kHz to 1MHz Programmable High-Frequency
Operation
• External Clock Synchronization Input
• Wide Input Operating Voltage Range (4.75V to 28V)
• Works for Input Voltage > 28V with External
Voltage Clamp on VIN for Boost Converter
• 20-Pin TQFN-EP and TSSOP-EP Packages
• Protection Features Increase System Reliability
• Programmable UVLO
• Programmable True Differential Overvoltage
Protection
• Fault Output (FLT) for Overvoltage, Overcurrent,
and Thermal-Warning Faults
Simplified Application Circuit
VIN BOOST LED DRIVER
LED+
ON
OFF
ANALOG
DIM
IN NDRV
MAX16834
PWMDIM
REFI
CS
DIMOUT
PGND
SENSE+
LEDs
LED-
Ordering Information and Pin Configurations appear at end
of data sheet.
19-4235; Rev 5; 1/15
1 page  
MAX16834
High-Power LED Driver with Integrated
High-Side LED Current Sense and
PWM Dimming MOSFET Driver
Typical Operating Characteristics
(VIN = VHV = 12V, VUVEN = 5V, VLV = VPWMDIM = VSGND, CVCC = 4.7μF, CLCV = 100nF, CREF = 100nF, RSENSE+ = 0.1Ω,
RRT = 10kΩ, TA = +25°C, unless otherwise noted.)
VREF vs. TEMPERATURE
3.74
3.72
3.70
3.68
3.66
3.64
3.62
VIN = 12V
3.60
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
3.80
3.75
3.70
3.65
3.60
3.55
3.50
4
VREF vs. SUPPLY VOLTAGE
8 12 16 20 24
SUPPLY VOLTAGE (V)
28
3.7020
3.7015
VREF vs. IREF
VIN = 12V
3.7010
3.7005
3.7000
3.6995
3.6990
3.6985
3.6980
0 1 2 3 4 5 6 7 8 9 10
IREF (mA)
20
18
16
14
12
10
8
6
4
2
0
4
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
PWMDIM = 0
8 12 16 20 24
SUPPLY VOLTAGE (V)
28
SUPPLY CURRENT
vs. TEMPERATURE
10
9
8
7
6
5
4
3
2
1
VIN = 12V
PWMDIM = 0
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
RT vs. SWITCHING FREQUENCY
100
10
VIN = 12V
1
100
SWITCHING FREQUENCY (kHz)
1000
SWITCHING FREQUENCY
vs. TEMPERATURE
605
604
603
602
601
600
599
598
597
596
595
594
593
592
591 VIN = 12V
590
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
7.16
7.14
7.12
7.10
7.08
7.06
7.04
7.02
7.00
6.98
6.96
6.94
6.92
6.90
0
VCC vs. ICC
VIN = 12V
10 20 30 40 50 60 70 80 90 100
ICC (mA)
VCC vs. ICC
7.2
TA = +125°C
VIN = 12V
7.1 TA = +100°C
7.0 TA = +25°C
TA = -40°C
6.9
6.8
0 10 20 30 40 50 60 70 80 90 100
ICC (mA)
www.maximintegrated.com
Maxim Integrated | 5
5 Page 
MAX16834
High-Power LED Driver with Integrated
High-Side LED Current Sense and
PWM Dimming MOSFET Driver
VIN
R1
R2
C1
LV FLT
IN NDRV
UVEN
HV
C2
CS
SC MAX16834
R3 PWMDIM
RT/SYNC
C5
VCC
DIMOUT
C4
REF
SENSE+
OVP+
R6
R5
REFI
CLV
COMP
SGND
PGND
Q1
ON
OFF
L1
D1
R4
LED+
C3
LEDs
LED-
Q2
R8
C7
C6
R7
R9
R10 C8
Figure 2. Boost LED Driver
Programming the LED Current
The LED current is programmed using the voltage on
REFI and the LED current-sense resistor R10 (see
Figure 2). The current is given by:
ILED
=
R10
VREF × R5
× (R6 + R5) ×
9.9
(A)
where VREF is 3.7V and the resistors R5, R6, and R10
are in ohms. The regulation voltage on the LED current-
sense resistor must not exceed 0.3V to prevent activa-
tion of the LED short-circuit protection circuit.
Boost Configuration
In the boost converter (Figure 2), the average inductor
current varies with the line voltage. The maximum aver-
age current occurs at the lowest line voltage. For the
boost converter, the average inductor current is equal
to the input current.
Calculate maximum duty cycle using the below equation.
DMAX
=
VLED + VD − VINMIN
VLED + VD − VFET
where VLED is the forward voltage of the LED string in
volts, VD is the forward drop of the rectifier diode D1 in
volts (approximately 0.6V), VINMIN is the minimum input
supply voltage in volts, and VFET is the average drain to
source voltage of the MOSFET Q1 in volts when it is on.
Use an approximate value of 0.2V initially to calculate
DMAX. A more accurate value of the maximum duty
cycle can be calculated once the power MOSFET is
selected based on the maximum inductor current.
Use the following equations to calculate the maximum
average inductor current ILAVG, peak-to-peak inductor
current ripple ΔIL, and the peak inductor current ILP in
amperes:
www.maximintegrated.com
Maxim Integrated | 11
11 Page | ||
| Páginas | Total 23 Páginas | |
| PDF Descargar | [ Datasheet MAX16834.PDF ] | |
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