AP3156 Datasheet, PDF (1/15 Pages) Diodes Incorporated – HIGH EFFICIENCY 1X/1.5X/2X CHARGE PUMP FOR WHITE LED APPLICATIONS

AP3156
HIGH EFFICIENCY 1X/1.5X/2X CHARGE PUMP
FOR WHITE LED APPLICATIONS
Features
• VIN Range: 2.7V to 5.5V
• Fully Programmable Current with Single Wire
• 32-Step Logarithmic Scale
• 20/25mA Max Current per Channel
• Four Low Current Settings Down to 50µA
• Low IQ (50µA) for Low Current Mode
• Tri-Mode 1X, 1.5X, and 2X Charge Pump for Maximum
Efficiency and VF Coverage
• Drives up to Six Channels of LEDs
• Individual Main/Sub-Group Control
• No Inductors, Low Noise Operation
• 0.5/1/2MHz Constant Switching Frequency
• Small Application Circuit
• Built-In Thermal Protection
• Built-In Auto-Disable For Open Circuit
• Automatic Soft Start
• IQ <1µA in Shutdown
• Thermally-Enhanced QFN4040-16 Package: Available
in “Green” Molding Compound (No Br, Sb)
• Lead Free Finish / RoHS Compliant (Note 1)
Applications
General Description
The AP3156 is a low noise, constant frequency charge pump
DC/DC converter that uses a tri-mode load switch (1X), fractional
(1.5X), and doubling (2X) conversion to maximize efficiency for
white LED applications. The AP3156 is capable of driving the
LED channels at 120mA maximum from a 2.7V to 5.5V input. The
current sinks may be operated individually or in parallel for driving
higher-current LEDs. A low external parts count (two 1µF flying
capacitors and two small 1µF capacitors at VIN and VOUT) make
this part ideally suited for small, battery-powered applications.
AP3156 serial digital input is used to enable, disable and set
current for each LED with a 32-level logarithmic scale plus four
low-current settings down to 50µA for optimized efficiency, with a
low quiescent current of only 50µA.
Each output of the AP3156 is equipped with built-in protection for
VOUT short circuit and auto-disable for LED failure conditions.
Built-in soft-start circuitry prevents excessive inrush current
during start-up. A low-current shutdown feature disconnects the
load from VIN and reduces quiescent current to less than 1µA.
The AP3156 is available in a lead-free, space-saving, thermally
enhanced 16-pin 4x4mm QFN package.
• Color (RGB) Lighting
• Programmable Current Sinks
• White LED Backlighting
• White Photo Flash for Digital Still Cameras
Typical Application Circuit
V_IN
1uF
C_IN
10 _VIN
C2_P ⁵
1uF
C2_N ⁸
C₂
C1_P ⁶
1uF
C1_N ⁷
C₁
AP3156
V_OUT ⁴
D6
D5
D4
D3
D2
D1
LED LED LED LED LED LED
2
SDI
SDI
1
D6
16
D5
D4 ¹⁵
D3 ¹⁴
D2 ¹³
D1 ¹²
GND
9,11
1uF
C_OUT
AP3156 Rev. 1
1 of 15
www.diodes.com
SEPTEMBER 2009
© Diodes Incorporated