LM2791LD-L/NOPB National Semiconductor, LM2791LD-L/NOPB Datasheet

IC LED DRIVR WHITE BCKLGT 10-LLP

LM2791LD-L/NOPB

Manufacturer Part Number
LM2791LD-L/NOPB
Description
IC LED DRIVR WHITE BCKLGT 10-LLP
Manufacturer
National Semiconductor
Type
Backlight, White LEDr
Datasheet

Specifications of LM2791LD-L/NOPB

Constant Current
Yes
Topology
PWM, Switched Capacitor (Charge Pump)
Number Of Outputs
2
Internal Driver
Yes
Type - Primary
Backlight
Type - Secondary
White LED
Frequency
450kHz ~ 850kHz
Voltage - Supply
3 V ~ 5.8 V
Mounting Type
Surface Mount
Package / Case
10-LLP
Operating Temperature
-30°C ~ 85°C
Current - Output / Channel
36mA
Internal Switch(s)
Yes
Operating Supply Voltage (typ)
3.3/5V
Number Of Segments
2
Operating Temperature (min)
-30C
Operating Temperature (max)
85C
Operating Temperature Classification
Commercial
Package Type
LLP EP
Pin Count
10
Mounting
Surface Mount
Power Dissipation
400mW
Operating Supply Voltage (min)
3V
Operating Supply Voltage (max)
5.8V
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Voltage - Output
-
Efficiency
-
Lead Free Status / Rohs Status
Compliant
Other names
LM2791LD-L
LM2791LD-LTR

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LM2791LD-L/NOPB
Manufacturer:
BOSCH
Quantity:
6 222
© 2002 National Semiconductor Corporation
LM2791
Current Regulated Switched Capacitor LED Driver with
Analog Brightness Control
General Description
The LM2791 is a CMOS charge-pump voltage doubler and
regulator that provides two regulated current sources. The
LM2791 is designed to drive two white (or blue) LEDs with
matched currents (within
sources for display backlights. They accept an input voltage
range from 3V to 5.8V and maintain a constant current
determined by an external set resistor.
The LM2791 delivers up to 36mA of load current to accom-
modate two high forward voltage (typically white) LEDs. The
switching frequency is 450kHz (min.) to keep the conducted
noise spectrum away from sensitive frequencies within por-
table RF devices.
In the LM2791, brightness is controlled by applying a voltage
between GND and 3.0V to the BRGT pin. The LM2791 is
available in active high or low shutdown versions. The shut-
down pin reduces the operating current to 1µA (max.).
The LM2791 is available in a 10 pin leadless leadframe
(LLP) CSP package.
Basic Application Circuit
±
0.3%) to produce balanced light
DS200183
Features
n Output matching of
n Drives up to two LED’s
n 3V to 5.8V Input Voltage
n Up to 36mA output current
n Soft start limits inrush current
n Analog brightness control
n Separate shutdown input
n Very small solution size - no inductor
n 0.7mA typical operating current
n 1µA (max.) shutdown current
n 450kHz switching frequency (min.)
n Linear regulation generates predictable noise spectrum
n LLP-10 package: 3mm X 3mm X 0.8mm
Applications
n White LED Display Backlights
n White LED Keypad Backlights
n 1-Cell Li-Ion battery-operated equipment including
n Flat Panel Dispalys
PDAs, hand-held PCs, cellular phones
±
20018301
0.3%
www.national.com
July 2002

Related parts for LM2791LD-L/NOPB

LM2791LD-L/NOPB Summary of contents

Page 1

... The shut- down pin reduces the operating current to 1µA (max.). The LM2791 is available pin leadless leadframe (LLP) CSP package. Basic Application Circuit © 2002 National Semiconductor Corporation Features n Output matching of n Drives up to two LED’ 5.8V Input Voltage ...

Page 2

... Connection Diagram Ordering Information Order Number Shutdown Polarity LM2791LD-L Active Low LM2791LDX-L Active Low LM2791LD-H Active High LM2791LDX-H Active High www.national.com 20018303 Top View 10-Lead LLP NSC Package Package Drawing Marking LLP-10 SNB LLP-10 SNB LLP-10 SLB LLP-10 SLB 2 Supplied As 1000 Units, Tape and Reel ...

Page 3

Pin Description Pin Name 1 BRGT Variable voltage input controls output current Charge pump output. OUT 3 C1− Connect this pin to the negative terminal of C1. 4 C1+ Connect this pin to the positive terminal of C1. ...

Page 4

... Note 4: The output switches operate at one half of the oscillator frequency, f Note 5: The interanl thresholds of the shutdown bar are set at about 40 Note 6: This electrical specification is guaranteed by design. Note 7: For more inforamtion regarding the LLP package, please refer to National Semiconductor Application note AN1187 www.national.com (Note 1) ...

Page 5

Typical Performance Characteristics V = 3.6V, BRGT pin =0V 330Ω DIODE SET Supply Current at No Load SD-Threshold Diode Current vs. Temperature Unless otherwise specified Supply Current vs Supply Voltage 20018305 20018308 20018320 5 , ...

Page 6

Typical Performance Characteristics V = 3.6V, BRGT pin =0V, R DIODE SET I vs BRGT DIODE Switching Frequency vs Supply Voltage Start Up Time @ www.national.com Unless otherwise specified 330Ω (Continued) 20018313 Switching Frequency vs. Temperature ...

Page 7

Typical Performance Characteristics V = 3.6V, BRGT pin =0V 330Ω (Continued) DIODE SET Start Up Time @ 4.2 V Unless otherwise specified 20018316 1uF 3.6V, IN HOLD IN ...

Page 8

Circuit Description The LM2791 provides two matched current sources for driv- ing high forward voltage drop LEDs from Li-Ion battery sources. The device has on-chip current regulators which are composed of current mirrors with ratio. The ...

Page 9

Application Information turning-on its own parasitic diode and potentially latching-up result important to select a schottky diode that will carry at least 200mA or higher current to charge the output capacitor during start-up. A schottky diode ...

Page 10

... National highly recommends a 1:1 ratio between the pack- age and the PCB thermal land. To further enhance thermal conductivity, the PCB thermal land may include vias to a ground plane. For more detailed instructions on mounting LLP packages, please refer to National Semiconductor Ap- plication Note AN-1187 ...

Page 11

... NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant ...

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