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OCP8138A
High Efficiency Synchronous Boost Converter
For 2.0A WLED Flash
General Description
The OCP8138A is a 2MHz fixed frequency
synchronous boost converter, optimized for maximum
2.0A camera flash application and maximum 800mA
movie mode applications using high-current white
LEDs in all single cell Li-ion powered products. An
adaptive regulation method ensures the current for
each LED remains in regulation and maximizes
efficiency.
Two simple logic control inputs (ENM and ENF)
enable and disable flash and movie mode operation of
the OCP8138A. Movie-mode and Flash-mode current
levels are independently fixed by two separate
resistors (RM and RF). For Flash mode, a default timer
can be used either to terminate a flash event or as a
safety flash timer. One or two LEDs can be connected
to the OCP8138A; in the case of two LEDs the output
current is matched between each diode.
Thermal regulation is integrated in Flash mode to
limit the ICs temperature and continuously provide the
maximum allowed output current.
The OCP8138A contain a thermal management
system to protect the device; a internal over-voltage
protection (OVP) circuitry prevents damaged to the
OCP8138A from open LED or open circuit conditions;
and a cycle-by-cycle current limit prevents damage to
the OCP8138A. Built-in circuitry prevents excessive
inrush current during start-up. The shutdown feature
reduces quiescent current to less than 1.0μA.
The 2MHz switching frequency allow for the use of
tiny, low profile (1uH or 2.2uH) inductors and 4.7uF
ceramic capacitors. The device is available in 14-pin
2mmX3mm DFN package and is rated over the -40°C
to 85°C.
Features
Input Voltage Range : 2.7V to 4.8V
Dual Channel Output
Drives up to 2.0A Regulated Output Current
(1.0A per Channel)
High Efficiency PWM Boost Converter
2.0MHz Fixed Switching Frequency
Up to 97% Efficiency with Small Inductor 1uH
Integrated Soft-Start Eliminates Inrush Current
Under Voltage Lock-Out
Over-Temperature Protection
Thermal Sensing and Current Scale Back
Over Voltage (Open LED) Protection
LED Short Circuit Protection
Movie Mode Dimming via Maximum 10KHz
PWM Control
800mS Flash Timer Control
Cycle by Cycle Current Limit
Separate Hardware Flash and Movie Enable
Independently Set Flash/Movie Currents
Flash Mode Current Up to 2.0A
Movie Mode Current Up to 800mA
Two Resistors Set Flash and Movie Current
Independently
Small Solution Size
Less than 1uA Shutdown Current
RoHS and Green Compliant
14-pin, 2mm X 3mm DFN Packages
-40to +85 Temperature Range
Applications
Camera Flashes and Movies
Cell Phones or Smart Phones
PDAs and Digital Camera
White LED Biasing
Mobil Handsets
Tablet PCs and Laptops/Netbooks
Camcorder Video Light (Movie Light)
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Pin Configuration
DFN2030-14L (Top View)
OCP8138A
Figure 1, Pin Assignments of OCP8138A
Pin
Name
Pin No.
DFN2030-
14L
I/O
Pin Function
Movie mode current setting input. A 34kΩ resistor from RM to GND sets the
RM
1
I/O
desired movie current available at LED1 and LED2 up to 400mA total current.
Each LED1 and LED2 channel will conduct 50% of the maximum
programmed current.
Flash mode current setting input. A 6.8kΩ resistor from RF to GND sets the
RF
2
I/O
maximum flash current available at LED1 and LED2 up to 2.0A total current.
Each LED1 and LED2 channel will conduct 50% of the maximum
programmed current.
AGND
3
P Analog Ground and flash ground.
VIN
4
P
Power input. Connect VIN to the input power supply voltage. Connect a 4.7uF
ceramic capacitor from VIN to GND as close as possible to OCP8138A.
SW 5 O Drain connection for internal NMOS and Synchronous PMOS Switches.
SW 6 O Drain connection for internal NMOS and Synchronous PMOS Switches.
PGND
7
P
Boost power ground pin. Connect PGND to GND and FGND at a single point
as close as possible to OCP8138A.
OUT
8, 9
Power output of the boost converter. Connect a 4.7uF ceramic capacitor from
O OUT to PGND as close as possible to the OCP8138A. Connect OUT to the
anodes of the Flash LEDs.
ENF
10
Flash mode enable pin. A low to high transition on the ENF pin initiates flash
I mode current level set by RF resistor. ENF is a active high control input with a
internal 300kΩ resistance to GND.
ENM
11
Movie mode enable pin. A low to high transition on the ENM pin initiates
I movie mode current level set by RM resistor. ENM is a active high control
input with a internal 300kΩ resistance to GND.
LED1
12
Channel 1 flash LED pin. Connect cathode of a flash LED to FGND. For a
O
single flash LED, connect LED1 and LED2 together. For two flash LEDs,
each output will conduct of 50% of the total flash current. LED1 is high
impedance during shutdown.
AGND
13
P Analog Ground and flash ground.
LED2
14
Channel 2 flash LED pin. Connect cathode of a flash LED to FGND. For a
O
single flash LED, connect LED1 and LED2 together. For two flash LEDs,
each output will conduct of 50% of the total flash current. LED2 is high
impedance during shutdown.
GND EP P Exposed paddle (bottom). Connect EP to PGND as close as possible.
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Typical Application Circuit
OCP8138A
Figure 2A, Typical Application Circuit of OCP8138A
Figure 2B, Typical Application Circuit of OCP8138A (One Channel)
Figure 2C, Typical Application Circuit of OCP8138A (One Channel)
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Ordering Information
OCP8138A
Part Number
OCP8138AVAD
Driver
Capability
2.0A or
2*1.0A
Package Type
DFN2030-14L
Package Qty
Temperature
7-in reel 3000pcs/reel -4085
Eco
Plan
Green
Lead
Cu
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Ver. 1.1 Feb .27, 2018
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