LM3501 Datasheet, PDF (1/27 Pages) National Semiconductor (TI) – Synchronous Step-up DC/DC Converter for White LED Applications

LM3501
www.ti.com
SNVS230C – DECEMBER 2003 – REVISED MAY 2013
LM3501 Synchronous Step-up DC/DC Converter for White LED Applications
Check for Samples: LM3501
FEATURES
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•2 Synchronous Rectification, High Efficiency
and no External Schottky Diode required
• Uses Small Surface Mount Components
• Can Drive 2-5 White LEDs in Series (May
Function with More Low V_F LEDs)
• 2.7V to 7V Input Range
• True Shutdown Isolation, no LED Leakage
Current
• DC Voltage LED Current Control
• Input Undervoltage Lockout
• Internal Output Over-Voltage Protection (OVP)
Circuitry, with no External Zener Diode
Required LM3501-16: 15.5V OVP; LM3501-21:
20.5V OVP.
• Requires Only a Small 16V (LM3501-16) or 25V
(LM3501-21) Ceramic Capacitor at the Input
and Output
• Thermal Shutdown
• 0.1µA shutdown Current
• Small 8-Bump Thin DSBGA Package
APPLICATIONS
• LCD Bias Supplies
• White LED Back-Lighting
• Handheld Devices
• Digital Cameras
• Portable Applications
DESCRIPTION
The LM3501 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 integrated synchronous switching (no external
schottky diode required) and a low feedback voltage
(515 mV), power efficiency of the LM3501 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 LM3501
operates with a fixed 1 MHz switching frequency.
When used with ceramic input and output capacitors,
the LM3501 provides a small, low-noise, low-cost
solution.
Typical Application Circuit
VIN
2.7V - 5.5V
Voltage
Control
CIN
1PF
Ceramic
>1.1V
<0.3V
L
22 PH
B1
VIN
C2
VSW
A3
CNTRL
LM3501-16
VOUT
C1
A2 _SHDN
FB ^B3
AGND GND
A1 C3
COUT
1PF
Ceramic
R2
24:
Figure 1. Typical 3 LED Application
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PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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