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PDF MAX16833B Data sheet ( Hoja de datos )
| Número de pieza | MAX16833B | |
| Descripción | High-Voltage HB LED Drivers | |
| Fabricantes | Maxim Integrated Products | |
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19-5187; Rev 0; 6/10
EVAALVUAAILTAIOBNLEKIT
www.DataSheet4U.com
High-Voltage HB LED Drivers with
Integrated High-Side Current Sense
General Description
The MAX16833/MAX16833B are peak current-mode-
controlled LED drivers for boost, buck-boost, SEPIC,
flyback, and high-side buck topologies. A dimming driver
designed to drive an external p-channel in series with the
LED string provides wide-range dimming control. This
feature provides extremely fast PWM current switching to
the LEDs with no transient overvoltage or undervoltage
conditions. In addition to PWM dimming, the MAX16833/
MAX16833B provide analog dimming using a DC input at
ICTRL. The MAX16833/MAX16833B sense the LED cur-
rent at the high side of the LED string.
A single resistor from RT/SYNC to ground sets the
switching frequency from 100kHz to 1MHz, while an
external clock signal capacitively coupled to RT/SYNC
allows the MAX16833 or MAX16833B to synchronize
to an external clock. In the MAX16833, the switching
frequency can be dithered for spread-spectrum applica-
tions. The MAX16833B instead provides a 1.64V refer-
ence voltage with a 2% tolerance.
The MAX16833/MAX16833B operate over a wide 5V to
65V supply range and include a 3A sink/source gate
driver for driving a power MOSFET in high-power LED
driver applications. Additional features include a fault-
indicator output (FLT) for short or overtemperature con-
ditions and an overvoltage-protection sense input (OVP)
for overvoltage protection. High-side current sensing
combined with a p-channel dimming MOSFET allow the
positive terminal of the LED string to be shorted to the
positive input terminal or to the negative input terminal
without any damage. This is a unique feature of the
MAX16833/MAX16833B.
Applications
Automotive Exterior Lighting:
High-Beam/Low-Beam/Signal/Position Lights
Daytime Running Lights (DRLs)
Fog Light and Adaptive Front Light Assemblies
Commercial, Industrial, and Architectural
Lighting
Ordering Information
PART
TEMP
RANGE
PIN-
PACKAGE
FUNCTIONALITY
MAX16833AUE+
-40NC to 16 TSSOP-
+125NC
EP*
Frequency
Dithering
Ordering Information continued at end of data sheet.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Features
S Boost, SEPIC, and Buck-Boost Single-Channel
LED Drivers
S +5V to +65V Wide Input Voltage Range with a
Maximum 65V Boost Output
S Integrated High-Side Current-Sense Amplifier
S ICTRL Pin for Analog Dimming
S Integrated High-Side pMOS Dimming MOSFET
Driver (Allows Single-Wire Connection to LEDs)
S Programmable Operating Frequency (100kHz to
1MHz) with Synchronization Capability
S Frequency Dithering for Spread-Spectrum
Applications (MAX16833)
S 2% Accurate 1.64V Reference (MAX16833B)
S Full-Scale, High-Side, Current-Sense Voltage of
200mV
S Short-Circuit, Overvoltage, and Thermal
Protection
S Fault Indicator Output
S -40NC to + 125NC Operating Temperature Range
S Thermally Enhanced 5mm x 4.4mm, 16-Pin TSSOP
Package with Exposed Pad
Simplified Operating Circuit
6V TO 18V WITH
LOAD DUMP
UP TO 70V
PWMDIM
IN
PWMDIM
NDRV
CS
OVP
ISENSE+
ISENSE-
DIMOUT
MAX16833
PGND
LED+
LED-
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1 page  
www.DataSheet4U.com
High-Voltage HB LED Drivers with
Integrated High-Side Current Sense
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 12V, RRT = 12.4kI, CIN = CVCC = 1µF, CLFRAMP/CREF = 0.1µF, NDRV = COMP = DIMOUT = PWMDIM = FLT = unconnected,
VOVP = VCS = VPGND = VSGND = 0V, VISENSE+ = VISENSE- = 45V, VICTRL = 1.40V, TA = TJ = -40NC to +125NC, unless otherwise
noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX UNITS
OPEN-DRAIN FAULT (FLT)
Output Voltage Low
Output Leakage Current
THERMAL SHUTDOWN
Thermal-Shutdown Temperature
Thermal-Shutdown Hysteresis
VOL-FLT
VIN = 4.75V, VOVP = 2V, and ISINK = 5mA
VFLT = 5V
Temperature rising
40
+160
10
200
1
mV
FA
NC
NC
Note 2: All devices are 100% tested at TA = +25NC. Limits over temperature are guaranteed by design.
Typical Operating Characteristics
(VIN = +12V, CVIN = CVCC = 1FF, CLFRAMP/CREF = 0.1FF, TA = +25NC, unless otherwise noted.)
IN RISING/FALLING UVLO THRESHOLD
vs. TEMPERATURE
4.8
4.7
VIN RISING
4.6
4.5
4.4
4.3 VIN FALLING
4.2
-40 -15 10 35 60 85 110 125
TEMPERATURE (°C)
VCC vs. IVCC
7.00
6.95
6.90
6.85
6.80
6.75
0
5 10 15 20 25 30 35 40 45 50
IVCC (mA)
QUIESCENT CURRENT
vs. TEMPERATURE
4
VPWMDIM = 0V
3
2
1
0
-40 -15 10 35 60 85 110 125
TEMPERATURE (°C)
VCC vs. TEMPERATURE
7.10
7.05
7.00
6.95
6.90
6.85
6.80
6.75
-40 -15
10 35 60 85 110 125
TEMPERATURE (°C)
QUIESCENT CURRENT vs. VIN
2.5
VPWMDIM = 0V
2.0 VIN ~ 4.6V
1.5
1.0
0.5
0
1 10 100
VIN (V)
DIMOUT (WITH RESPECT TO ISENSE+)
vs. TEMPERATURE
-6.2
-6.7
-7.2
-7.7
-8.2
-8.7
-40 -15
10 35 60 85 110 125
TEMPERATURE (°C)
_______________________________________________________________________________________ 5
5 Page 
www.DataSheet4U.com
High-Voltage HB LED Drivers with
Integrated High-Side Current Sense
Detailed Description
The MAX16833/MAX16833B are peak current-mode-
controlled LED drivers for boost, buck-boost, SEPIC,
flyback, and high-side buck topologies. A low-side gate
driver capable of sinking and sourcing 3A can drive a
power MOSFET in the 100kHz to 1MHz frequency range.
Constant-frequency peak current-mode control is used
to control the duty cycle of the PWM controller that drives
the power MOSFET. Externally programmable slope
compensation prevents subharmonic oscillations for
duty cycles exceeding 50% when the inductor is operat-
ing in continuous conduction mode. Most of the power
for the internal control circuitry inside the MAX16833/
MAX16833B is provided from an internal 5V regulator.
The gate drive for the low-side switching MOSFET is
provided by a separate VCC regulator. A dimming driver
designed to drive an external p-channel in series with
the LED string provides wide-range dimming control.
This dimming driver is powered by a separate floating
reference -7V regulator. This feature provides extremely
fast PWM current switching to the LEDs with no transient
overvoltage or undervoltage conditions. In addition to
PWM dimming, the MAX16833/MAX16833B provide ana-
log dimming using a DC input at the ICTRL input.
A single resistor from RT/SYNC to ground sets the
switching frequency from 100kHz to 1MHz, while an
external clock signal capacitively coupled to RT/SYNC
allows the MAX16833/MAX16833B to synchronize to an
external clock. The switching frequency can be dithered
for spread-spectrum applications by connecting the
LFRAMP output to RT/SYNC through an external resis-
tor in the MAX16833. In the MAX16833B, the LFRAMP
output is replaced by a REF output, which provides a
regulated 1.64V, 2% accurate reference that can be
used with a resistive divider from REF to ICTRL to set the
LED current. The maximum current from the REF output
cannot exceed 80FA.
Additional features include a fault-indicator output (FLT)
for short, overvoltage, or overtemperature conditions
and an overvoltage-protection (OVP) sense input for
overvoltage protection. In case of LED string short, for
a buck-boost configuration, the short-circuit current is
equal to the programmed LED current. In the case of
boost configuration, the MAX16833/MAX16833B enter
hiccup mode with automatic recovery from short circuit.
UVLO
The MAX16833/MAX16833B feature undervoltage lock-
out (UVLO) using the positive power-supply input (IN).
The MAX16833/MAX16833B are enabled when VIN
exceeds the 4.6V (typ) threshold and are disabled when
VIN drops below the 4.35V (typ) threshold. The UVLO
is internally fixed and cannot be adjusted. There is a
startup delay of 1024 clock cycles on power-up after the
UVLO threshold is crossed. There is a 3.3Fs delay on
power-down on the falling edge of the UVLO.
Dimming MOSFET Driver (DIMOUT)
The MAX16833/MAX16833B require an external p-chan-
nel MOSFET for PWM dimming. For normal operation,
connect the gate of the MOSFET to the output of the
dimming driver (DIMOUT). The dimming driver can sink
up to 25mA or source up to 50mA of peak current for
fast charging and discharging of the p-MOSFET gate.
When the PWMDIM signal is high, this driver pulls the
p-MOSFET gate to 7V below the ISENSE+ pin to com-
pletely turn on the p-channel dimming MOSFET.
n-Channel MOSFET Switch Driver (NDRV)
The MAX16833/MAX16833B drive an external n-channel
switching MOSFET. NDRV swings between VCC and
PGND. NDRV can sink/source 3A of peak current, allow-
ing the MAX16833/MAX16833B to switch MOSFETs in
high-power applications. The average current demand-
ed from the supply to drive the external MOSFET
depends on the total gate charge (QG) and the operat-
ing frequency of the converter, fSW. Use the following
equation to calculate the driver supply current INDRV
required for the switching MOSFET:
INDRV = QG x fSW
Pulse-Dimming Input (PWMDIM)
The MAX16833/MAX16833B offer a dimming input
(PWMDIM) for pulse-width modulating the output current.
PWM dimming can be achieved by driving PWMDIM with
a pulsating voltage source. When the voltage at PWMDIM
is greater than 1.23V, the PWM dimming p-channel
MOSFET turns on and the gate drive to the n-channel
switching MOSFET is also enabled. When the voltage on
PWMDIM drops 70mV below 1.23V, the PWM dimming
MOSFET turns off and the n-channel switching MOSFET
is also turned off. The COMP capacitor is also discon-
nected from the internal transconductance amplifier when
PWMDIM is low. When left unconnected, a weak internal
pullup resistor sets this input to logic-high.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 22 Páginas | |
| PDF Descargar | [ Datasheet MAX16833B.PDF ] | |
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