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OCP8111
1.0A Buck/Boost Charge Pump LED Driver
„ General Description
The OCP8111 is current-regulated charge pump
ideal for powering high brightness LEDs for camera
flash applications. The charge pump can be set to
regulate two current levels for FLASH and TORCH
modes.
The OCP8111 automatically switches modes
between step-up and step-down ensuring that LED
current does not depend on the forward voltage. It
switches at 1.8MHz, allowing the use of tiny
components. The supply voltage ranges from 2.7V to
5.5V and is ideally suited for all applications powered by
a single Li_Ion battery cell or three to four NiCd, NiMH,
or Alkaline battery cells.
The OCP8111 also features a very low shutdown
current (less than 1uA), an automatic soft-start mode to
limit inrush current, as well as over current, over voltage
and over temperature shutdown control.
A Low current sense reference voltage (50mV)
allows the user of small 0603 current sensing resistors.
The OCP8111 is offered in Green 10-pin DFN
package and is specified over an ambient temperature
range of -40˚C to 85˚C.
„ Features
z Output Current up to 1.0A at VIN=4.2V
z Up to 94% Efficiency in Torch Mode
z Adjustable FLASH Mode Current
z Minimum External Components: No Inductors
z Automatic Buck/Boost Mode Switchover
z Wide VIN Range: 2.7V to 5.5V
z High Frequency Operation: 1.8MHz
z 50mV Reference for low Loss Sensing
z ISD < 1μA in Shutdown
z PWM Dimming Control
z Automatic Soft Start Limits Inrush Current
z Over Voltage Protection on Output
z Over Current Protection
z Over Temperature Protection
z Low Input and Output Ripple and Low EMI
z Ultra-low Dropout Voltage in Buck Mode
z Space Saving RoHS Compliant, Lead Free
Package: 10-pin 3mm x 3mm DFN
„ Applications
z White LED Torch/Flash for Cell Phones, DSCs,
and Camcorders
z White LED Backlighting
z Generic Lighting/Flash/Strobe Applications
z General Purpose High Current Boost
„ Pin Configuration
DFN3030-10L (Top View)
Figure 1, Pin Assignments of OCP8111
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OCP8111
1.0A Buck/Boost Charge Pump LED Driver
Pin
Name
VIN
C1
C2
FLASH
EN
RSET
FB
SGND
PGND
VOUT
GND
Pin No.
DFN3030-10
1
2
3
4
5
6
7
8
9
10
Pin Function
Input Voltage for the charge pump. Decouple with 4.7µF or 10uF ceramic capacitor
close to the pins of the IC.
Positive input for the external flying capacitor. Connect a ceramic 1 µF capacitor
close to the pins of the IC.
Negative input for the external flying capacitor. Connect a ceramic 1 µF capacitor
close to the pins of the IC.
Logic input to toggle operation between FLASH and TORCH mode. In TORCH
mode FB is regulated to the internal 50mV reference. In FLASH mode FB
reference voltage can be adjusted by changing the resistor from RSET pin to
ground. Choose the external current sense resistor (RSENSE) based on desired
current in TORCH mode. This pin does not have an internal pull-up/pull- down; do
not leave this pin floating.
Shutdown control input. Connect to VIN for normal operation, connect to ground for
shutdown. Don’t leave this pin floating.
Connect a resistor from this pin to ground. When in FLASH mode (FLASH = High)
this resistor sets the current regulation point according to the following:
VFB
= 14uA * RSET
5
(Flash Mode)
Feedback input for the current control loop. Connect directly to the current sense
resistor.
Internal ground pin. Control circuitry returns current to this pin.
Power ground pin. Flying capacitor current returns through this pin.
Charge Pump Output Voltage. Decouple with an external capacitor. At least 1 µF is
recommended. Higher capacitor values reduce output ripple
Exposed Pad Exposed pad should be soldered to PCB board and connected to GND.
„ Typical Application Circuit
Figure 2, Typical Application Circuit of OCP8111
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„ Block Diagram
OCP8111
1.0A Buck/Boost Charge Pump LED Driver
Figure 3, Block Diagram of OCP8111
„ Absolute Maximum Ratings1 (TA=25°C unless otherwise noted)
Parameter
Symbol
Input Voltage
VEN ,ISET,VOUT Voltage
Storage Temperature Range
Operating Junction Temperature Range
VIN
TS
TJ
Maximum Power Dissipation
PD
Maximum Thermal Resistance
ESD (HBM)
θJA
ESD
Output Current Pulse (Flash)
Output Current Continuous (Torch)
IOUT
IOUT
Rating
-0.3 to 6
-0.3 to VIN
-55 to +150
-40 to 150
1.9
51
4K
1.6
0.4
„ Recommended Operating Conditions (TA=25°C unless otherwise noted)
Parameter
Symbol
Conditions
Rating
Supply Voltage
VIN Operating
2.7 ~ 5.5
Operating Temperature Range
TA Operating
-40 ~ +85
Unit
V
V
W
/W
V
A
A
Unit
V
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OCP8111
1.0A Buck/Boost Charge Pump LED Driver
„ Electrical Characteristics
(Unless otherwise notedtypical values are at TA=25, VIN=3.6V, CFC=1uF, COUT=10uF)
Symbol
Parameter
Conditions
Min.
Input Power Supply
VIN Input Voltage range
ISD Shutdown Current
IQ Quiescent Current
EN=0V,Shutdown mode
VIN = 2.7 - 5.5V, FLASH = GND,
1X Mode, ILOAD =100μA
FLASH = HIGH, 2X Mode
2.7
-
-
-
VFB FB Reference voltage
FLASH = GND
45
FLASH = High, RSET = 53.6 k138
VFBR FB Reference Voltage Range
IFB FB Pin Current
Charge Pump Section
R2X
Charge Pump Equivalent
Resistance (x2 mode)
FLASH = High. Guaranteed by
design.
VFB= 0.3V
VFB = 0.0V, VIN= 3.6V
100
-
-
R1X
Charge Pump Equivalent
Resistance (x1 mode)
VIN= 3.6V
-
TSS VOUT Turn-on Time
VIN= 3.6V, FB within 90% of
regulation
-
FOSC
VOUT
TSD
Switching Frequency
Over-voltage Limit
Shutdown Temperature
LED unconnected, VIN =4.2V
Temperature rising
-
-
-
TRT Recovery Temperature
Temperature falling
-
ENABLE
VENL
VENH
ILK
TFLASH
Enable Threshold Low
Enable Threshold High
EN, FLASH Pin Current
Maximum Flash ON time
FLASH = High
-
1.4
-
1.2
Typ.
-
0.1
0.34
1.75
50
150
-
-
4
0.4
140
1.8
5.1
145
135
-
-
-
-
Max.
5.5
1
2
-
55
162
400
1
Unit
V
μA
mA
mA
mV
mV
mV
μA
-Ω
0.7 Ω
250 μs
- MHz
-V
-
-
0.4 V
-V
1 μA
3.8 s
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OCP8111
1.0A Buck/Boost Charge Pump LED Driver
„ Typical Performance Characteristics:
(Unless otherwise notedTA=25, VIN=3.6V, CIN=10uF, CFC=1uF, COUT=10uF)
Figure 4, Output Current vs. Supply Voltage
Figure 5, VFB vs. RSET Resistance
Figure 6, Flash 700mA Output Current vs. VIN
Figure 7, Torch Output Current vs. VIN
Figure 8, Torch in 1X to Flash in 1X, VIN=4.2V
Figure 9, Torch in 1X to Flash in 2X, VIN=3.6V
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Ver. 1.4 Feb.04, 2013