LM2707MF/NOPB National Semiconductor, LM2707MF/NOPB Datasheet

IC LED DRVR WHITE BCKLGT SOT23-8

LM2707MF/NOPB

Manufacturer Part Number
LM2707MF/NOPB
Description
IC LED DRVR WHITE BCKLGT SOT23-8
Manufacturer
National Semiconductor
Type
Backlight, White LEDr
Datasheet

Specifications of LM2707MF/NOPB

Topology
PWM, Step-Up (Boost)
Number Of Outputs
1
Internal Driver
Yes
Type - Primary
Backlight, Flash/Torch
Type - Secondary
White LED
Frequency
50kHz
Voltage - Supply
2.3 V ~ 7 V
Voltage - Output
18V
Mounting Type
Surface Mount
Package / Case
SOT-23-8
Operating Temperature
-30°C ~ 85°C
Current - Output / Channel
30mA
Internal Switch(s)
Yes
Efficiency
80%
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
LM2707MF
© 2005 National Semiconductor Corporation
LM2707
Inductive-Boost Series LED Driver with Programmable
Oscillator Frequency
General Description
The LM2707 is a magnetic boost regulator specifically de-
signed for white LED drive applications. Tightly regulated
LED currents, exceptional LED brightness uniformity, and
very high LED-drive power efficiency (
achieved by stacking the LEDs in series between the
LM2707 output and the low-voltage feedback pin (0.515V).
The LM2707 requires only a few small external components.
A small inductor with a low saturation current rating can
safely be used because the tightly controlled current limit
circuit prevents large inductor current spikes, even at start-
up. The output capacitor can also be small due to the tightly
controlled output over-voltage protection circuit.
The LM2707 is an excellent choice for display backlighting
and other general-purpose lighting functions in battery pow-
ered applications. The 2.3V-to-7V input voltage range of the
device easily accommodates single-cell Lithium-Ion batter-
ies and battery chargers.
The LM2707 features 18V output capability, PFM regulation,
and a high-current switching transistor (400mA peak). These
characteristics allow the part to drive a series string of 2-to-4
LEDs with forward currents between 0 and 40mA. LED
brightness can be adjusted dynamically simply by applying a
PWM signal to the enable (EN) pin. The PWM signal can be
as fast as 50kHz because the LM2707 has a fast turn-on
time.
In addition to LED-drive applications, the LM2707 can also
be used as a general purpose DC-DC voltage regulator in
boost converter applications.
The LM2707 is available in a SOT23-8 surface mount pack-
age.
Typical Application Circuit
DS200992
>
80%) can all be
Features
n Excellent LED Drive Capability:
n Very High LED Drive Efficiency:
n Low Feedback Voltage: 515mV
n Low-Resistance NMOS Power Switch: 0.6Ω
n High-Speed PWM Brightness Control Capability
n Over-Voltage Protection (18V min, 19V typ, 20V max)
n Inrush and Inductor Current Limiting
n 2.3V - 7V Input Voltage Range
n Requires Only a Few External Components
n No External Compensation Needed
n Programmable Oscillator Frequency
n ON/OFF Pin
n Small SOT23-8 Package
Applications
n White LED Drive for Display Backlights
n LED Flashlights
n General Purpose LED Lighting
n Step-up DC/DC Voltage Conversion
3 LED String: 30mA
4 LED String: 20 mA
6 LEDs (2 strings of 3): 15 mA
20099225
>
80%
February 2005
www.national.com

Related parts for LM2707MF/NOPB

LM2707MF/NOPB Summary of contents

Page 1

... In addition to LED-drive applications, the LM2707 can also be used as a general purpose DC-DC voltage regulator in boost converter applications. The LM2707 is available in a SOT23-8 surface mount pack- age. Typical Application Circuit © 2005 National Semiconductor Corporation Features n Excellent LED Drive Capability: 3 LED String: 30mA 4 LED String > ...

Page 2

... LM2707 is ON when V(EN) is above 1.2V LM2707 is Shutdown when V(EN) is below 0.3V Order Information Order Number Package Marking LM2707MF S0TB LM2707MFX S0TB www.national.com 8-Pin SOT23 Package National Semiconductor Package Number MF08A Package Supplied as: SOT23-8 Tape and Reel, 1000 Units/Reel (MF08A) Tape and Reel, 3500 Units/Reel 2 20099226 ...

Page 3

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications FB, and EN pins IN SW and V pins OVP Continuous Power Dissipation Switch Peak Current Junction Temperature (T ) J-MAX Storage Temperature Range Maximum Lead Temperature ...

Page 4

... Electrical Characteristics tables. Note 2: All voltages are with respect to the potential at the GND pin. Note 3: For detailed soldering specifications and information, please consult the National Semiconductor Application Note titled: "Mounting of Surface Mount Components". Note 4: The Human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin. (MIL-STD-883 3015.7) The machine model is a 200pF capacitor discharged directly into each pin ...

Page 5

Typical Performance Characteristics (Coilcraft DT1608C-223 MBR0520L (Vishay), C Oscillator Frequency vs. Temperature C = 10pF X Oscillator Period vs. Cx Capacitance Maximum Duty Cycle vs. Temperature C = 10pF X Unless otherwise specified 1.0µ ...

Page 6

Typical Performance Characteristics (Coilcraft DT1608C-223 MBR0520L (Vishay), C Feedback Trip Point vs. Supply Voltage Switch Resistance (R ) vs. Switch Current DS-ON Pin 1-2 Resistance vs. Temperature www.national.com Unless otherwise specified 1.0µ 2x1µF, C ...

Page 7

Typical Performance Characteristics (Coilcraft DT1608C-223 MBR0520L (Vishay), C Shutdown Supply Current vs. Supply Voltage Supply Current vs. EN Input Voltage EN Threshold vs. Supply Voltage Unless otherwise specified 1.0µ 2x1µ 68pF, T ...

Page 8

Typical Performance Characteristics (Coilcraft DT1608C-223 MBR0520L (Vishay), C LED Drive Efficiency vs. Supply Voltage 2 LEDs (Note 11) LED Drive Efficiency vs. Supply Voltage 4 LEDs (Note 11) * 20mA, 4-LED operation requires increasing the current limit. A ...

Page 9

Block Diagram FIGURE 1. LM2707 Block Diagram 9 20099227 www.national.com ...

Page 10

Simplified Switching Circuit Product Description OVERVIEW The LM2707 is a magnetic switch-mode boost converter that has been designed specifically for driving white LEDs. The device is an asynchronous boost regulator that uses a low- resistance internal NFET power transistor and ...

Page 11

Product Description (Continued) An example with C = 68pF 26.3MHz / (15 + 68) = 317kHz. OSC The minimum recommended C capacitance is 10pF. X The rise time ( the C signal is 2.2x longer ...

Page 12

Product Description Figure 5 graphs the relationship between inductor current and current limit. Figure 6 plots ideal inductor current wave- forms to illustrate inductor current behavior. Figure 7 gives peak inductor current versus input voltage and shows the two regions ...

Page 13

Product Description (Continued Internal Resistance Betwen Rearranging the equation above allows for easy calculation of an external resistance to obtain a desired peak inductor current: OUTPUT OVER-VOLTAGE PROTECTION The LM2707 contains an over-voltage protection circuit ...

Page 14

Components and Connectivity (Continued These capacitors have tight capacitance tolerance (as OUT good as +/-10%) and hold their value over temperature (X7R: +/-15% over –55˚C to 125˚C; X5R: +/-15% over –55˚C to 85˚C). Capacitors with a Y5V or ...

Page 15

Application Information Table 1. Time-Averaged LED Current vs. PWM Frequency and Duty Cycle PWM Frequency D = 10% 200 Hz 2.3 1 kHz 3.7 10 kHz 2.6 20 kHz 1.0 40 kHz OFF 50 kHz OFF V = 3.6V, 4 ...

Page 16

Application Information FIGURE 11. LM2707 LED-Drive Circuit with 2-Bit Digital Logic Brightness Control Application Circuits LM2707 DRIVING 6 LEDs www.national.com (Continued) 16 20099236 20099237 ...

Page 17

Application Circuits (Continued) LM2707 DRIVING 3 LEDs LM2707 DRIVING 2 LEDs 20099238 20099239 17 www.national.com ...

Page 18

Application Circuits LM2707 DC-DC VOLTAGE CONVERTER CIRCUIT Curves for V = 12V 126kΩ, R OUT FB1 2x1µ 68pF OUT X A accomodate load currents above of 15mA. Output Voltage vs. ...

Page 19

... BANNED SUBSTANCE COMPLIANCE National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. ...

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