lm27965sqx-m National Semiconductor Corporation, lm27965sqx-m Datasheet

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lm27965sqx-m

Manufacturer Part Number
lm27965sqx-m
Description
Dual Display White Led Driver With I2c Compatible Brightness Control
Manufacturer
National Semiconductor Corporation
Datasheet
© 2007 National Semiconductor Corporation
LM27965
Dual Display White LED Driver with I2C Compatible
Brightness Control
General Description
The LM27965 is a highly integrated charge-pump-based du-
al-display LED driver. The device can drive up to 9 LEDs in
parallel with a total output current of 180mA. Regulated inter-
nal current sinks deliver excellent current and brightness
matching in all LEDs.
The LED driver current sinks are split into three independently
controlled groups. The primary group can beconfigurabled
with 4 or 5 LEDs, for backlighting a larger main display and
the second group can be configured with 2 or 3 LEDs, for
backlighing a smaller secondary display. An additional, inde-
pendently controlled led driver is provided for driving an indi-
cator or general purpose LED. The LM27965 has an I
compatible interface that allows the user to independently
control the brightness on each bank of LEDs.
The device provides excellent efficiency without the use of an
inductor by operating the charge pump in a gain of 3/2, or in
Pass-Mode. The proper gain for maintaining current regula-
tion is chosen based on LED forward voltage, so that effi-
ciency is maximized over the input voltage range.
The LM27965 is available in National's small 24-pin Leadless
Leadframe Package (LLP-24).
Typical Application Circuit
201550
2
C
Features
Applications
91% Peak LED Drive Efficiency
No Inductor Required
0.3% Current Matching
Drives LEDs with up to 30mA per LED
180mA of total drive current
I
Adaptive 1× - 3/2× Charge Pump
Resistor-Programmable Current Settings
External Chip RESET Pin
Extended Li-Ion Input: 2.7V to 5.5V
Small low profile industry standard leadless package, LLP
24 : (4mm x 4mm x 0.8mm)
25mm
Two I
LM27965SQ and 0x38 for LM27965SQ-M
Mobile Phone Display Lighting
PDA Backlighting
General LED Lighting
2
C Compatible Brightness Control Interface
2
2
C Compatible Chip Address Options: 0x36 for
total solution size
20155001
www.national.com
October 2007

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lm27965sqx-m Summary of contents

Page 1

... LED forward voltage, so that effi- ciency is maximized over the input voltage range. The LM27965 is available in National's small 24-pin Leadless Leadframe Package (LLP-24). Typical Application Circuit © 2007 National Semiconductor Corporation Features ■ 91% Peak LED Drive Efficiency ■ No Inductor Required ■ ...

Page 2

... NC Ordering Information Order Information Compatible Chip Address LM27965SQ LM27965SQX LM27965SQ-M LM27965SQX-M www.national.com 24 Pin Quad LLP Package NS Package Number SQA24A Pin Descriptions Input voltage. Input range: 2.7V to 5.5V. Charge Pump Output Voltage Flying Capacitor Connections LED Drivers - GroupA LED Drivers - GroupB LED Driver - Indicator LED ...

Page 3

Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. V pin voltage IN SCL, SDIO, VIO, RESET pin voltages I Pin Voltages Dxx Continuous Power Dissipation (Note 3) ...

Page 4

Symbol Parameter V Reset Voltage Thresholds RESET Compatible Interface Voltage Specifications (SCL, SDIO, VIO) V Serial Bus Voltage Level IO V Input Logic Low "0" Input Logic High "1" Output Logic Low "0" ...

Page 5

AVG and (AVG-MIN)/AVG. The largest number of the two (worst case) is considered the matching figure for the bank. The matching figure for a given part is considered to be the highest matching figure of the two banks. The typical ...

Page 6

Typical Performance Characteristics 3.6V; R LEDxA LEDxB LED1C SET LED Drive Efficiency vs Input Voltage BankA Current Regulation vs Input Voltage BankC Current Regulation vs Input Voltage www.national.com Unless otherwise specified 16.9kΩ; ...

Page 7

BankB Current Matching vs Input Voltage BankB Diode Current vs Brightness Register Code BankA Diode Current vs Brightness Register Code 20155032 20155027 7 20155026 www.national.com ...

Page 8

Circuit Description OVERVIEW The LM27965 is a white LED driver system based upon an adaptive 3/2× - 1× CMOS charge pump capable of supplying up to 180mA of total output current. With three separately controlled banks of constant current sinks, ...

Page 9

The third byte contains data to write to the selected register. ack = acknowledge (SDIO pulled down by either master or slave chip address, 36h for LM27965 or ...

Page 10

Brightness Level Control Table (BankA and BankB) Brightness Code (hex ...

Page 11

The statement above is a simple example of the LED drive capabilities of the LM27965. The statement contains the key application parameters that are required to validate an LED- drive design using the LM27965: LED current (I of active LEDs ...

Page 12

V is the nominal LED forward voltage the number of LED LEDs and I is the programmed LED current. LED DISS IN LEDA P = (GAIN × V × I DISS ...

Page 13

Physical Dimensions inches (millimeters) unless otherwise noted SQA24: 24 Lead LLP X1 = 4.0mm X2 = 4.0mm X3 = 0.8mm 13 www.national.com ...

Page 14

... National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. ...

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