Diodes AP3156 - Manual

AP3156
HIGH EFFICIENCY 1X/1.5X/2X CHARGE PUMP
FOR WHITE LED APPLICATIONS
AP3156 Rev. 1 1 of 15 SEPTEMBER 2009
www.diodes.com © Diodes Incorporated
• V
IN
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 I
Q
(50µA) for Low Current Mode
• Tri-Mode 1X, 1.5X, and 2X Charge Pump for Maximum
Efficiency and V
F
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
• I
Q
<1µA in Shutdown
•
Thermally-Enhanced QFN4040-16 Package: Available
in “Green” Molding Compound (No Br, Sb)
• Lead Free Finish / RoHS Compliant (Note 1)
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 V
IN
and V
OUT
) 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
V
OUT
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 V
IN
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.
Applications
• Color (RGB) Lighting
•
Programmable Current Sinks
• White LED Backlighting
• White Photo Flash for Digital Still Cameras
Typical Application Circuit
V
IN
1uF
C
IN
AP3156
C2
P
C2
N
C1
N
V
OUT
D4
D1
D2
D3
GND
SDI SDI
2
10
V
IN
1uF
C
2 8
5
1uF
C
1 7
6
C1
P
9,11
4
15
D6
LED
14
D5
LED
13
D4
LED
12
D3
LED
1uF
C
OUT
D5
D6
1
16
D2
LED
D1
LED
Features General Description