LM3500TL-16EV National Semiconductor, LM3500TL-16EV Datasheet

BOARD EVALUATION LM3500TL-16

LM3500TL-16EV

Manufacturer Part Number
LM3500TL-16EV
Description
BOARD EVALUATION LM3500TL-16
Manufacturer
National Semiconductor
Series
PowerWise®r
Datasheets
1.LM3500TL-21NOPB.pdf (20 pages)
2.LM3500TL-16EV.pdf (2 pages)

Specifications of LM3500TL-16EV

Current - Output / Channel
20mA
Outputs And Type
1, Non-Isolated
Voltage - Output
14V
Features
Shutdown
Voltage - Input
2.7 ~ 5.5 V
Utilized Ic / Part
LM3500
Core Chip
LM3500
Topology
Buck
No. Of Outputs
1
Output Voltage
16V
Input Voltage
2.7V To 7V
Kit Contents
Board
Development Tool Type
Hardware - Eval/Demo Board
Lead Free Status / RoHS Status
Not applicable / Not applicable
© 2007 National Semiconductor Corporation
LM3500
Synchronous Step-up DC/DC Converter for White LED
Applications
General Description
The LM3500 is a fixed-frequency step-up DC/DC converter
that is ideal for driving white LEDs for display backlighting and
other lighting functions. With fully intergrated synchronous
switching (no external schottky diode required) and a low
feedback voltage (500mV), power efficiency of the LM3500
circuit has been optimized for lighting applications in wireless
phones and other portable products (single cell Li-Ion or 3-
cell NiMH battery supplies). The LM3500 operates with a fixed
1MHz switching frequency. When used with ceramic input
and output capacitors, the LM3500 provides a small, low-
noise, low-cost solution.
Two LM3500 options are available with different output volt-
age capabilities. The LM3500-21 has a maximum output
voltage of 21V and is typically suited for driving 4 or 5 white
LEDs in series. The LM3500-16 has a maximum output volt-
age of 16V and is typically suited for driving 3 or 4 white LEDs
in series (maximum number of series LEDs dependent on
LED forward voltage). If the primary white LED network
should be disconnected, the LM3500 uses internal protection
circuitry on the output to prevent a destructive over-voltage
event.
A single external resistor is used to set the maximum LED
current in LED-drive applications. The LED current can easily
be adjusted using a pulse width modulated (PWM) signal on
the shutdown pin. In shutdown, the LM3500 completely dis-
connects the input from output, creating total isolation and
preventing any leakage currents from trickling into the LEDs.
Typical Application Circuit
200657
Features
■
■
■
■
■
■
■
■
■
■
■
Applications
■
■
■
■
■
Synchronous rectification, high efficiency and no external
schottky diode required
Uses small surface mount components
Can drive 2-5 white LEDs in series
2.7V to 7V input range
Internal output over-voltage protection (OVP) circuitry,
with no external zener diode required
True shutdown isolation
Input undervoltage lockout
Requires only small ceramic capacitors at the input and
output
Thermal Shutdown
0.1µA shutdown current
Small 8-bump thin micro SMD package
LCD Bias Supplies
White LED Backlighting
Handheld Devices
Digital Cameras
Portable Applications
(may function with more low-V
LM3500-16: 15.5V OVP; LM3500-21: 20.5V OVP.
20065701
F
LEDs)
February 2005
www.national.com

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LM3500TL-16EV Summary of contents

Page 1

... In shutdown, the LM3500 completely dis- connects the input from output, creating total isolation and preventing any leakage currents from trickling into the LEDs. Typical Application Circuit © 2007 National Semiconductor Corporation Features ■ Synchronous rectification, high efficiency and no external schottky diode required ■ ...

Page 2

... Connection Diagram Ordering Information Maximum Order Number Output Voltage 16V LM3500TL-16 16V LM3500TLX-16 21V LM3500TL-21 21V LM3500TLX-21 Pin Description/Functions Pin Name A1 AGND Analog ground Analog and Power supply input PMOS source connection for synchronous rectification. OUT C2 V Switch pin. Drain connections of both NMOS and PMOS power devices. ...

Page 3

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications (LM3500-16)(Note 2) OUT V (LM3500-21)(Note 2) OUT V (Note 2) SW FB, SHDN, and NC Voltages Maximum Junction Temperature Lead Temperature (Note 3) ESD Ratings (Note 4) Human Body Model ...

Page 4

Symbol Parameter OVP Output Overvoltage Protection (LM3500-16) Output Overvoltage Protection (LM3500-21 Bias Current Vout OUT (LM3500-16) V Bias Current OUT (LM3500-21) I PMOS Switch Leakage VL Current (LM3500-16) PMOS Switch Leakage Current (LM3500-21) SHDN SHDN Low Threshold SHDN ...

Page 5

... IN OUT Note 3: For more detailed soldering information and specifications, please refer to National Semiconductor Application Note 1112: Micro SMD Wafer Level Chip Scale Package (AN-1112), available at www.national.com. Note 4: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF capacitor discharged directly into each pin ...

Page 6

LED Efficiency vs LED Current L = Coilcraft DT1608C-223, Efficiency = 100*( LED Efficiency vs LED Current L = Coilcraft DT1608C-223, Efficiency = 100*( LED Efficiency vs LED Current L = Coilcraft DT1608C-223, Efficiency = ...

Page 7

LED Efficiency Coilcraft DT1608C-223, Efficiency = 100*(P /( LED LED 20065769 4 LED Efficiency Coilcraft DT1608C-223, Efficiency = 100*(P /( LED LED 20065773 ...

Page 8

Switch Current Limit vs V Switch Current Limit vs Temperature LM3500-16, V OUT Switch Current Limit vs Temperature LM3500-21, V www.national.com : LM3500-16 IN 20065762 =12V 20065776 =8V OUT 20065792 8 Switch Current Limit vs Temperature LM3500-16, V =8V OUT ...

Page 9

Switch Current Limit vs Temperature LM3500-21, V =18V OUT 20065794 V DC Bias vs V Voltage: LM3500-16 OUT OUT 20065765 FB Voltage vs Temperature 20065766 Oscillator Frequency Bias vs V Voltage: LM3500-21 OUT OUT FB Voltage ...

Page 10

NMOS R DSON (I = 300mA) SW Typical V Ripple IN = 22Ω, V LM3500-16, 3 LEDs 3.0V LED IN 1) SW, 10V/div 100mA/div 100mV/div ...

Page 11

Typical V Ripple, OVP Functioning: LM3500-16 OUT V open circuit and equals approximately 15V DC, V OUT 200mV/div, AC OUT T = 1ms/div Typical V OUT 20065782 V open circuit and equals approximately 20V DC ...

Page 12

Operation The LM3500 utilizes a synchronous Current Mode PWM con- trol scheme to regulate the feedback voltage over almost all load conditions. The DC/DC controller acts as a controlled current source ideal for white LED applications. The LM3500 is internally ...

Page 13

Application Information ADJUSTING LED CURRENT The White LED current is set using the following equation: The LED current can be controlled using a PWM signal on the SHDN pin with frequencies in the range of 100Hz (greater than visible frequency ...

Page 14

Typical Peak Inductor Currents (mA) # LEDs LED Current (V) series 2 100 134 3 118 138 190 4 142 174 244 5 191 232 319 3 ...

Page 15

FIGURE 2. Evaluation Board Layout (2X Magnification) Top Layer FIGURE 3. Evaluation Board Layout (2X Magnification) Bottom Layer (as viewed from the top) 15 20065777 20065778 www.national.com ...

Page 16

FIGURE 4. 2 White LED Application FIGURE 5. Multiple 2 LED String Application 16 20065709 20065754 ...

Page 17

FIGURE 6. Multiple 3 LED String Application FIGURE 7. LM3500-21 5 LED Application 17 20065783 20065790 www.national.com ...

Page 18

www.national.com 18 ...

Page 19

Physical Dimensions inches (millimeters) unless otherwise noted For Ordering, Refer to Ordering Information Table X1 = 1.92mm (±0.03mm 1.92mm (±0.03mm 0.6mm (±0.075mm) 8-Bump Micro SMD Package (TL) NS Package Number TLA08SSA 19 www.national.com ...

Page 20

... 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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