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PDF MAX17127 Data sheet ( Hoja de datos )
| Número de pieza | MAX17127 | |
| Descripción | Six-String WLED Driver | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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19-5164; Rev 0; 3/10
EVAALVUAAILTAIOBNLEKIT
Six-String WLED Driver with Integrated
Step-Up Converter
General Description
The MAX17127 is a high-efficiency driver for white light-
emitting diodes (LEDs). It is designed for large liquid-
crystal displays (LCDs) that employ an array of LEDs as
the light source. An internal switch current-mode step-up
converter drives the LED array, which can be configured
for up to six strings in parallel and 13 LEDs per string.
Each string is terminated with ballast that achieves Q2%
current-regulation accuracy, ensuring even LED bright-
ness. The MAX17127 has a wide input voltage range
from 5V to 26V, and provides adjustable 10mA to 30mA
full-scale LED current.
The MAX17127 can implement brightness control through
the PWM signal input, and LED current is directly con-
trolled by the external dimming signal’s frequency and
duty cycle.
The MAX17127 has multiple features to protect the con-
troller from fault conditions. Once an open/short string is
detected, the fault string is disabled while other strings
can still operate normally. The controller features cycle-
by-cycle current limit to provide constant operation and
soft-start capability. If the MAX17127 is in current-limit
condition, the step-up converter is latched off after an
internal timer expires. A thermal-shutdown circuit pro-
vides another level of protection. When thermal shut-
down happens, the MAX17127 is latched off.
The MAX17127’s step-up controller features an inter-
nal 0.12I (typ), 48V (max) power MOSFET with local
current-sense amplifier for accurate cycle-by-cycle cur-
rent limit. This architecture greatly simplifies the external
circuitry and saves PCB space. Low-feedback volt-
age at each LED string helps reduce power loss and
improve efficiency. The MAX17127 features resistor-
adjustable switching frequency from 250kHz to 1MHz,
which enables a wide variety of applications that can
trade off component size for operating frequency.
The MAX17127 is available in a thermally enhanced,
lead-free, 20-pin, 4mm x 4mm thin QFN package.
Features
S 5V to 26V Input Supply Voltage
S Up to Six Parallel Strings Multiple Series-
Connected LEDs
S 250kHz to 1MHz Adjustable Switching Frequency
S 0.12I Internal HV Power MOSFET (48V max)
S Low String Feedback Voltage: 480mV at 20mA
LED Current
S Full-Scale LED Current Adjustable from 10mA to
30mA
S Q2% Current-Regulation Accuracy Between
Strings
S 400ns Minimum String On-Time
S 100Hz to 25kHz PWM Input Range
S Open and Short LED Protection
S Output Overvoltage Protection
S Thermal Shutdown
S Small 20-Pin, 4mm x 4mm Thin QFN Package
Ordering Information
PART
MAX17127ETP+
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
20 TQFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Applications
Notebook, Subnotebook, and Tablet Computer
Displays
Automotive Systems
Handy Terminals
Simplified Operating Circuit appears at end of data sheet.
________________________________________________________________ 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  
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Six-String WLED Driver with Integrated
Step-Up Converter
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1. VIN = 12V, CCOMP = 0.51nF, CCOUT = 4.7µF, RCOMP = 82.5kΩ, RISET = 180kΩ, RFSLCT = 100kΩ, L = 10µH,
TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
FB_ Minimum On-Time
FAULT PROTECTION
OVP Threshold Voltage
Rising edge, typical hysteresis = 90mV
FB_ Overvoltage Threshold
FB_ Open Threshold Voltage
FB_ Check LED Source Current
FB_ Check LED Time
Overcurrent Fault Timer
Latch-off timer
PWM CONTROL
PWM Input On-Time
PWM Input Frequency Range
Note 1: Specifications are guaranteed by design, not production tested.
MIN TYP MAX UNITS
400 700 ns
1.23
7
130
0.4
0.7
88
1.27
9
280
1.3
1.3
168
V
V
mV
mA
ms
μs
400 ns
0.1 25 kHz
Typical Operating Characteristics
(Circuit of Figure 1. VIN = 12V, TA = +25NC, unless otherwise noted.)
BOOST CONVERTER EFFICIENCY vs. INPUT VOLTAGE (VS)
(VOUT = 32V, IOUT = 120mA, BRIGHTNESS = 100%)
92
90
88
86
84
82
80
78
5
8 11 14 17 20 23 26
INPUT VOLTAGE (V)
BOOST CONVERTER EFFICIENCY vs. BRIGHTNESS
(VS = 2V, VOUT = 32V, IOUT = 120mA AT 100%)
90
80
70
60
50
0
20 40 60 80
BRIGHTNESS (%)
100
_______________________________________________________________________________________ 5
5 Page 
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Six-String WLED Driver with Integrated
Step-Up Converter
The MAX17127 typical operating circuit is shown as
Figure 1. Table 1 lists some recommended components,
Typical Operating Circuit
and Table 2 lists the contact information for component
suppliers.
VS
5V TO 26V
CIN
4.7µF
VIN
0.1µF
1µF
RISET
180kI
RFSLCT
100kI
3.3V
10kI
FAULT INDICATOR
L1
10µH D1
VIN
VDDIO
ISET
FSLCT
SW
PGND
OVP
COMP
AGND
RCOMP
82.5kI
MAX17127
I.C.
EN
PWM
R_FPWM
FPO
EP
FB1
FB2
FB3
FB4
FB5
FB6
COUT
4.7µF
R1
2.21MI
CCOMP
510pF
R2
71.5kI
Figure 1. Typical Operating Circuit
Table 1. Component List
DESIGNATION
DESCRIPTION
4.7FF Q10%, 25V X5R ceramic capacitor
CIN (1206)
Murata GRM319R61E475KA12D
C1, C2
2.2FF Q20%, 50V X7R ceramic capacitors
(1206)
Murata GRM31CR71H225K
D1
2A, 40V Schottky diode (M-flat)
Toshiba CMS11
DESIGNATION
L1
White LED
DESCRIPTION
10FH, 1.2A power inductor
Sumida CR6D09HPNP-100MC
TDK VLP6810T-100M1R2
3.2V (typ), 3.5V (max) at 20mA
Nichia NSSW008C
______________________________________________________________________________________ 11
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| Páginas | Total 22 Páginas | |
| PDF Descargar | [ Datasheet MAX17127.PDF ] | |
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