Datasheets»National Semiconductor (acquired by TI (Texas Instruments))»LM3528TMEV Datasheet

LM3528TMEV Datasheet

Download or read online National Semiconductor LM3528TMEV BOARD EVAL FOR LM3528 12MCRSMD pdf datasheet.
Also see for LM3528TMEV: Datasheet #2 (8 pages)



Page
1 of 32
next
LM3528
High Efficiency, Multi Display LED Driver with 128
Exponential Dimming Steps and Integrated OLED Power
Supply in a 1.2mm × 1.6mm µSMD Package
General Description
The LM3528 current mode boost converter offers two sepa-
rate outputs. The first output (MAIN) is a constant current sink
for driving series white LED’s. The second output (SUB/FB)
is configurable as a constant current sink for series white LED
bias, or as a feedback pin to set a constant output voltage for
powering OLED panels.
As a dual output white LED bias supply, the LM3528 adap-
tively regulates the supply voltage of the LED strings to max-
imize efficiency and insure the current sinks remain in
regulation. The maximum current per output is set via a single
external low power resistor. An I
2
C compatible interface al-
lows for independent adjustment of the LED current in either
output from 0 to max current in 128 exponential steps. When
configured as a white LED + OLED bias supply the LM3528
can independently and simultaneously drive a string of up to
6 white LED’s and deliver a constant output voltage of up to
21V for OLED panels.
Output over-voltage protection shuts down the device if
V
rises above 22V allowing for the use of small sized low
OUT
voltage output capacitors. Other features include a dedicated
general purpose I/O (GPIO) and a multi-function pin (HWEN/
PGEN/GPIO) which can be configured as a 32 bit pattern
generator, a hardware enable input, or as a GPIO. When
configured as a pattern generator, an arbitrary pattern is pro-
grammed via the I
2
C compatible interface and output at
HWEN/PGEN/GPIO for indicator LED flashing or for external
logic control. The LM3528 is offered in a tiny 12-bump µSMD
package and operates over the -40°C to +85°C temperature
range.
Typical Application Circuit
© 2008 National Semiconductor Corporation
Features
128 Exponential Dimming Steps
Programmable Auto-Dimming Function
Up to 90% Efficient
Low Profile 12 Bump µ-SMD Package (1.2mm x 1.6mm x
0.6mm)
Integrated OLED Display Power Supply and LED Driver
Programmable Pattern Generator Output for LED
Indicator Function
Drives up to 12 LED’s at 20mA
Drives up to 5 LED’s at 20mA and delivers 18V at 40mA
1% Accurate Current Matching Between Strings
Internal Soft-Start Limits Inrush Current
True Shutdown Isolation for LED’s
Wide 2.5V to 5.5V Input Voltage Range
22V Over-Voltage Protection
1.25MHz Fixed Frequency Operation
Dedicated Programmable General Purpose I/O
Active Low Hardware Reset
Applications
Dual Display LCD Backlighting for Portable Applications
Large Format LCD Backlighting
OLED Panel Power Supply
Display Backlighting with Indicator Light
30020501
300205
August 3, 2008
30020563
Typical PCB Layout
www.national.com
Specifications of National Semiconductor LM3528TMEV
Current - Output / Channel:
20mA
Features:
Dimmable, I²C Interface
Outputs And Type:
2, Non-Isolated
Series:
-
Utilized Ic / Part:
LM3528
Voltage - Input:
2.5 ~ 5.5V
Voltage - Output:
21V

Summary of Contents

Page 1

... HWEN/PGEN/GPIO for indicator LED flashing or for external logic control. The LM3528 is offered in a tiny 12-bump µSMD package and operates over the -40°C to 85°C temperature range. Typical Application Circuit © 2008 National Semiconductor Corporation Features 128 Exponential Dimming Steps ...

Page 2

Connection Diagram Ordering Information Order Number Package Type LM3528TME 12-Bump µSMD LM3528TMX 12-Bump µSMD Pin Descriptions/Functions Pin Name A1 OVP Over-Voltage Protection Sense Connection. Connect OVP to the positive terminal of the output capacitor. A2 MAIN Main Current Sink Input. ...

Page 3

... Junction to Ambient Thermal -65°C to 150°C Resistance (θ ESD Caution Notice 300°C National Semiconductor recommends that all integrated cir- 2.5kV cuits be handled with appropriate ESD precautions. Failure to observe proper ESD handling techniques can result in dam- age to the device. 25°C and those in boldface type apply over the Operating Temperature Range ...

Page 4

... For guaranteed specifications and test conditions, see the Electrical Characteristics. Note 2: All voltages are with respect to the potential at the GND pin. Note 3: For detailed soldering specifications and information, please refer to National Semiconductor Application Note 1112: Micro SMD Wafer LEvel Chip Scale Package (AN-1112). ...

Page 5

Timing Diagram FIGURE Timing 5 30020503 www.national.com ...

Page 6

Typical Performance Characteristics Mode 2.2µF (OLED Mode), C OUT 25°C unless otherwise specified. SUB MAIN A 2x6 LED Efficiency Strings of 6LEDs) 2x4 LED Efficiency Strings ...

Page 7

LED Efficiency vs I LED (2 Strings of 2LEDs) 30020512 18V OLED Efficiency vs I OUT 30020514 LED Efficiency TDK VLF3012AT-100MR92 40mA) 12V OLED Efficiency 0.36Ω ...

Page 8

LED Line Regulation (UNI '0') OLED Line Regulation I 60mA OLED www.national.com OLED Line Regulation I OLED 30020516 OLED Load Regulation V OLED 30020518 8 60mA 30020517 18V 30020519 ...

Page 9

OLED Load Regulation V 12V OLED 30020520 Over Voltage Limit vs 30020522 Peak Current Limit vs. V Switch On-Resistance vs 30020521 IN 30020523 www.national.com ...

Page 10

Switching Frequency vs. V Shutdown Current vs. V www.national.com Maximum Duty Cycle vs 30020524 Switching Supply Current vs 30020526 10 IN 30020525 IN 30020527 ...

Page 11

LED Current Matching vs. CODE (Note 11) (UNI '1 12kΩ -40°C to 85°C) SET A LED Current vs CODE ( 12kΩ±0.05%) MAIN SUB IDEAL SET LED Current Accuracy ...

Page 12

Start-Up Waveform (LED Mode) (2 × 5 LEDs, 20mA per string) Channel 2: SDA (5V/div) Channel 1: V (10V/div) OUT Channel 3: I (20mA/div) LED Channel 4: I (200mA/div) IN Time Base: 400µs/div Load Step (OLED Mode 18V, ...

Page 13

Line Step (OLED Mode 18V 2.2µF, V OUT OUT IN Channel 2: VOUT (AC Coupled, 100mV/div) Channel 3: VIN (AC Coupled, 500mV/div) Time Base: 200µs/div GPIO1 Functionality (GPIO1 Configured as OUTPUT, f Channel 2: GPIO (2V/div) ...

Page 14

Block Diagram Operation Description The LM3528 Current Mode PWM boost converter operates from a 2.7V to 5.5V input and provides two regulated outputs for White LED and OLED display biasing. The first output, MAIN, provides a constant current of up ...

Page 15

FB room at the input to the current sinks for proper current regulation. In the instance when there are unequal numbers of LEDs or unequal currents from string to string, the ...

Page 16

Figures 12 - 15). Figure 16 details an example bit pat- tern at a specific programmed duty cycle and frequency. A 1 written to the PGEN_ registers forces HWEN/PGEN/GPIO low. A 0 causes HWEN/PGEN/GPIO to go open ...

Page 17

COMPATIBLE INTERFACE The LM3528 is controlled via compatible interface. 2 START and STOP conditions classify the beginning and the end of the session. A START condition is defined as SDA transitioning ...

Page 18

REGISTER DESCRIPTIONS There are 4, 8 bit registers within the LM3528 as detailed in Table 1. TABLE 1. LM3528 Register Descriptions Register Name General Purpose (GP) Brightness Main (BMAIN) Brightness Sub (BSUB) HWEN/PGEN/GPIO Control (HPG) General Purpose I/O Control (GPIO) ...

Page 19

TABLE 3. Operational Truth Table UNI OLED ENM ENM ,ENS, or OLED high enables analog ...

Page 20

TABLE 4. I vs. Brightness Register Data LED BMAIN BMAIN or BSUB I BSUB LED_MAX Brightness Brightness Data Data 0000000 0.000% 0100000 0000001 0.166% 0100001 0000010 0.175% 0100010 0000011 0.184% 0100011 0000100 0.194% 0100100 0000101 0.204% 0100101 ...

Page 21

BRIGHTNESS RATE OF CHANGE DESCRIPTION RMP0 and RMP1 control the rate of change of the LED cur- rent I and I in response to changes in BMAIN and/ MAIN SUB/FB or BSUB. There are 4 user programmable LED current rates ...

Page 22

TABLE 6. HPG Register Function Bits 7 6 Bits (PGEN Bit 2 (GPIO (PGEN Bit Enable/Disable Period) and Duty Cycle Selection 1.6µs/ 001 100% X bit (625kHz) 010 1/2 ...

Page 23

GPIO Register Function Bits GPIO Data Data (Bit 1) Direction (Bit Figures 12 15 detail the Pattern Generator Data Registers. These hold the 32 bit data that is output ...

Page 24

Figure 16 shows a write sequence to the pattern generator programmed to output the waveform in Figure 17. In this ex- ample HPG register bits <7:6> (for 26ms/bit) and bits <5:3> 010 (for 1/2 duty cycle). The ...

Page 25

SHUTDOWN AND OUTPUT ISOLATION The LM3528 provides a true shutdown for either MAIN or SUB/FB when configured as a White LED bias supply. Write ENM (bit 1) of the General Purpose register to turn off the MAIN ...

Page 26

Application Information LED CURRENT SETTING/MAXIMUM LED CURRENT Connect a resistor (R ) from SET to GND to program the SET maximum LED current (I ) into MAIN or SUB/FB. The LED_MAX relationship is: SET LED_MAX where SET ...

Page 27

TABLE 7. Recommended Output Capacitors Manufacturer Part Number TDK C1608X5R1E105M Murata GRM39X5R105K25D539 TDK C2012X5R1E225M Murata GRM219R61E225KA12 INDUCTOR SELECTION The LM3528 is designed for use with a 10µH inductor, how- ever 22µH are suitable providing the output capacitor is in- creased ...

Page 28

TABLE 9. Recommended Schottky Diodes Manufacturer Part Number On Semiconductor NSR0230P2T5G On Semicondcuctor NSR0230M2T5G On Semiconductor RB521S30T1 Diodes Inc. SDM20U30 Diodes Inc. B05030WS Philips BAT760 OUTPUT CURRENT RANGE (OLED MODE) The maximum output current the LM3528 can deliver in OLED ...

Page 29

APPLICATION CIRCUITS FIGURE 19. LED Backlight OLED Power Supply LAYOUT CONSIDERATIONS Refer to AN-1112 for µSMD package soldering The high switching frequencies and large peak currents in the LM3528 make the PCB layout a critical part of the design. ...

Page 30

Physical Dimensions X1 1.215mm (±0.1mm 1.615mm (±0.1mm 0.6mm www.national.com inches (millimeters) unless otherwise noted 12 Bump µSMD For Ordering, Refer to Ordering Information Table NS Package Number TMD12 30 ...

Page 31

Notes 31 www.national.com ...

Page 32

... For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Amplifiers www.national.com/amplifiers Audio www.national.com/audio Clock Conditioners www.national.com/timing Data Converters www.national.com/adc Displays www.national.com/displays Ethernet www.national.com/ethernet Interface www.national.com/interface LVDS www.national.com/lvds Power Management www.national.com/power Switching Regulators www.national.com/switchers LDOs www ...

Comments to this Datasheet