LM3492MHX/NOPB National Semiconductor, LM3492MHX/NOPB Datasheet

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LM3492MHX/NOPB

Manufacturer Part Number
LM3492MHX/NOPB
Description
IC LED DRIVER DIMMING 20TSSOP
Manufacturer
National Semiconductor
Datasheet

Specifications of LM3492MHX/NOPB

Internal Driver
Yes
Type - Primary
Automotive, Backlight
Type - Secondary
High Brightness LED (HBLED)
Mounting Type
Surface Mount
Topology
Step-Up (Boost)
Number Of Outputs
2
Frequency
200kHz ~ 1MHz
Voltage - Supply
4.5 V ~ 65 V
Package / Case
20-TSSOP (0.173", 4.40mm Width) Exposed Pad
Operating Temperature
-40°C ~ 125°C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Voltage - Output
-

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LM3492MHX/NOPB
Manufacturer:
TI/德州仪器
Quantity:
20 000
Part Number:
LM3492MHX/NOPB
0
© 2010 National Semiconductor Corporation
Two-Channel Individual Dimmable LED Driver with Boost
Converter and Fast Current Regulator
General Description
The LM3492 integrates a boost converter and a two-channel
current regulator to implement a high efficient and cost effec-
tive LED driver for driving two individually dimmable LED
strings with a maximum power of 15W and an output voltage
of up to 65V. The boost converter employs a proprietary Pro-
jected-On-Time control method to give a fast transient re-
sponse with no compensation required, and a nearly constant
switching frequency programmable from 200 kHz to 1 MHz.
The application circuit is stable with ceramic capacitors and
produces no audible noise on dimming. The programmable
peak current limit and soft-start features reduce current
surges at startup, and an integrated 190 mΩ, 3.9A N-Channel
MOSFET switch minimizes the solution size. The fast slew
rate current regulator allows high frequency and narrow pulse
width dimming signals to achieve a very high contrast ratio of
1000:1 at a dimming frequency of more than 3 kHz. The LED
current is programmable from 50 mA to 200 mA by a single
resistor.
To maximize the efficiency, Dynamic Headroom Control
(DHC) automatically adjusts the output voltage to a minimum.
DHC also facilitates a single BOM for different number of LED
in a string, which is required for backlight panels of different
size, thereby reducing overall development time and cost.
The LM3492 comes with a versatile COMM pin which serves
as a bi-directional I/O pin interfacing with an external MCU for
the following functions: power-good, over-temperature, IOUT
over- and under-voltage indications, switching frequency tun-
ing, and channel 1 disabling. Other supervisory functions of
the LM3492 include precise enable, VCC under-voltage lock-
out, current regulator over-power protection, and thermal
shutdown protection. The LM3492 is available in the thermally
enhanced eTSSOP-20 package.
301161
LM3492/LM3492Q
Features
Boost Converter:
Current Regulators:
Supervisory Functions:
Applications
LM3492Q is an Automotive Grade Product that is AEC
Q100 grade 1 qualified
Very wide input voltage ranged from 4.5V-65V
Programmable soft-start
No loop compensation required
Stable with ceramic and other low ESR capacitors with no
audible noise
Nearly constant switching frequency programmable from
200 kHz to 1 MHz
Programmable LED current from 50 mA to 200 mA
1000:1 contrast ratio at a dimming frequency of more than
3 kHz, minimum LED current pulse width is 300 ns
Two individual dimmable LED strings up to 65V, total 15W
(typically 28 LEDs @ 150 mA)
Dynamic Headroom Control maximizes efficiency
Over-Power protection
±3% current accuracy
Precision enable
COMM I/O pin for diagnostic and commands
Thermal shutdown protection
Thermally enhanced eTSSOP-20 package
Ultra-high contrast ratio 6.5”-10” LCD display backlight up
to 28 LEDs
Automotive or marine GPS display
October 15, 2010
www.national.com

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LM3492MHX/NOPB Summary of contents

Page 1

... Other supervisory functions of the LM3492 include precise enable, VCC under-voltage lock- out, current regulator over-power protection, and thermal shutdown protection. The LM3492 is available in the thermally enhanced eTSSOP-20 package. © 2010 National Semiconductor Corporation LM3492/LM3492Q Features Boost Converter: ■ ...

Page 2

Typical Application Connection Diagram Ordering Information Order Number Package Type LM3492MH Exposed Pad TSSOP-20 LM3492MHX LM3492QMH LM3492QMHX *Automotive Grade (Q) product incorporates enhanced manufacturing and support processes for the automotive market, including defect detection methodologies. Reliability qualification is compliant with ...

Page 3

Pin Descriptions Pin Name Description 1 EN Enable 2 VIN Input Supply Voltage Switch Node 5 VOUT Output Voltage Sense 6 RT Frequency Control 7 FB Output Voltage Feedback 8 GND Analog Ground 9 IOUT2 Current Regulator ...

Page 4

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VIN, RT, VOUT to GND SW to GND SW to GND (Transient) ILIM to GND FB to GND COMM, DIM1, DIM2, to GND Electrical Characteristics apply over the full Operating Junction Temperature (T statistical correlation ...

Page 5

Symbol Parameter Boost Converter I CDHC pin source current CDHC-SRC I CDHC pin sink current CDHC-SINK I CDHC pin leakage current CDHC-LEAKAGE I Integrated MOSFET peak current limit CL-MAX threshold I Half integrated MOSFET peak current limit CL-HALF threshold R ...

Page 6

Typical Performance Characteristics Unless otherwise specified the following conditions apply 200 mA shown in this datasheet. LED Quiescent Current Regulation vs Temperature LED www.national.com = 25° 12V with configuration ...

Page 7

Efficiency 0.2A) IN LED 30116117 Power 0.2A) LED 30116119 Steady State Operation (I = 0.2A) LED 30116121 I Regulation vs V LED ( = 0.2A) ILED Enable Transient (I LED LED 50% Dimming ...

Page 8

LED Dimming (I = 0.2A, Dimming frequency = 200Hz) LED Simplified Functional Block Diagram www.national.com 300 ns LED Dimming Pulse Width (I = 0.2A, Dimming frequency = 3.33 kHz) LED 30116123 8 30116124 30116103 ...

Page 9

Overview The LM3492 integrates a boost converter and a two-channel current regulator to implement a high efficient and cost effec- tive LED driver for driving two individually dimmable LED strings with a maximum power of 15W and an output voltage ...

Page 10

Current Limit The current limit I of the integrated MOSFET of the LM3492 CL provides a cycle-by-cycle current limit for protection. It ...

Page 11

If the voltage on the IOUTn ( pin is over 24V when channel n is on, the regulated current of channel n will be reduced linearly if the voltage further increases (as shown in Figure 5). The ...

Page 12

CDHC pin reaches its maximum, and these conditions last for 508 consecutively dimming signals applied on the DIMn pin. This means that the current of the LED string n does not reach its regulated value. ...

Page 13

As a result 1.98A. A standard value of 47 µH is L1(PEAK) selected for L , and its saturation current is larger than 1.98A The selection of the boost diode tors. The ...

Page 14

Physical Dimensions www.national.com inches (millimeters) unless otherwise noted 20-Lead Plastic eTSSOP Package NS Package Number MXA20A 14 ...

Page 15

Notes 15 www.national.com ...

Page 16

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