WD3124DC
WD3124DC
1000mA Buck/Boost
Charge Pump Flash LED Driver
Description
The WD3124DC is a 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
WD3124DC
automatically
switches
modes
VIN
1
Http//:www.sh-willsemi.com
DFN3x3-10L
10
VOUT
C1
2
9
PGND
between step-up and step-down ensuring that LED
current does not depend on the forward voltage. It
switches at 2.2MHz, 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 WD3124DC also features a very low shutdown
current, an automatic soft-start mode to limit inrush
current, as well as over current, over voltage and
over-Thermal shutdown control.
A low current sense reference voltage (50mV) allows
the use of small 0603 current sensing resistors.
The WD3124DC is available in Green DFN3×3-10L
package and is specified over an ambient temperature
range of -40
℃
to +85℃.
C2
3
8
SGND
FLASH
4
7
FB
EN
5
GND
6
RSET
Pin configuration (Top view)
WD3124DC
3124DC = Device code
Y
W
= Year code
= Week code
Marking
Features
● Output Current up to 1000mA
● Up to 95% Efficiency in Torch Mode
● Adjustable FLASH Mode Current
● Automatic Buck/Boost Mode Switchover
● Wide Input Voltage Range: 2.7V to 5.5V
● Minimum External Components: No Inductors
● High Frequency Operation: 2.2MHz
● Low 50mV Reference for Low Loss Sensing
● PWM Dimming Control
● Automatic Soft Start Limits Inrush Current
● Low Ripple and EMI
Will Semiconductor Ltd.
1
Order Information
Device
Function
Package
Shipping
WD3124DC-10/TR
With timeout
DFN3x3-10L
3000/Reel&Tape
Applications
Cellphones
PADs
Dec, 2014 - Rev. 1.1
WD3124DC
Pin configuration (Top view)
Pin descriptions
Symbol
VIN
C1
C2
DFN3x3-10L
1
2
3
Descriptions
Input voltage for the charge pump. Decouple with 4.7μF or 10μF ceramic
capacitor close to the pins of the IC.
Positive input for the external flying capacitor. Connect a ceramic 1μF
capacitor close to the pins of the IC.
Negative input for the external flying capacitor. Connect a ceramic 1μF
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
FLASH
4
mode FB reference voltage can be adjusted by changing the resistor from
R
SET
pin to ground. Choose the external current sense resistor (R
SENSE
) based
on desired current in TORCH mode and Flash mode.
Shutdown control input. Connect to VIN for normal operation, connect to
EN
5
ground for shutdown. For normal operation, suggest connecting to VIN only
after the VIN has settled if the VIN ramping up is slow.
Connect a resistor from this pin to ground. When in FLASH mode (FLASH =
R
SET
6
High) this resistor sets the current regulation point according to the following:
VFB =(1.38V / R
SET
)x10.2kΩ
FB
SGND
PGND
VOUT
7
8
9
10
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
1μF is recommended. If Higher value capacitor is used, output ripple is
smaller.
Will Semiconductor Ltd.
2
Dec, 2014 - Rev. 1.1
WD3124DC
Typical applications
Figure1. Single LED flash circuit @ 700mA flash current
Figure 2. Multiple LED flash circuit @1000mA flash current
Figure 3. Two LED flash circuit @ 1000mA flash current
Will Semiconductor Ltd.
3
Dec, 2014 - Rev. 1.1
WD3124DC
Block diagram
Absolute maximum ratings
Parameter
VIN,VOUT pin voltage range
EN, FB pin voltage range
Output Current Pulse(Flash)
Output Current Continuous(Torch)
Power Dissipation (Note 1)
Junction to Ambient Thermal Resistance (Note 1)
Symbol
V
-
I
O(Flash)
I
O(Torch)
R
θJA
T
J
T
L
Topr
Tstg
HBM
MM
Value
-0.3½6
-0.3½5.5
1.5
0.4
3
57
150
260
-40 ~ 85
-55 ~ 150
8000
400
Unit
V
V
A
A
W
o
C/W
o
o
o
o
Junction temperature
Lead temperature(Soldering, 10s)
Operating ambient temperature
Storage temperature
ESD Ratings
C
C
C
C
V
V
These are stress ratings only. Stresses exceeding the range specified under “Absolute Maximum Ratings” may cause
substantial damage to the device. Functional operation of this device at other conditions beyond those listed in the
specification is not implied and prolonged exposure to extreme conditions may affect device reliability.
Note 1:
Surface mounted on FR-4 Board using 1 square inch pad size, dual side, 1oz copper
Will Semiconductor Ltd.
4
Dec, 2014 - Rev. 1.1
WD3124DC
Electronics Characteristics
(Full= -40
℃
to +85
℃
，V
IN
= 3.6V, C
IN
= 4.7uF, C
F
= C
OUT
= 1uF, V
EN
= V
IN
,
otherwise noted)
Parameter
Input Voltage Range
Quiescent Current
Shutdown Supply Current
Feedback
Voltage
FB Pin Current
Oscillator Frequency
Charge Pump Equivalent
Resistance (1× mode)
Charge Pump Equivalent
Resistance (2× mode)
EN, FLASH Logic Low
EN, FLASH Logic High
EN, FLASH Pin Current
V
OUT
Turn-on Time
Thermal Shutdown
Temperature
Maximum Flash ON time
T
SHDN
V
IN
= 3.6V
0.8
V
EN,FLASH H
V
EN,FLASH L
I
EN,FLASH
V
IN
= 3.6V, FB within 90% of
regulation
250
150
1.2
1.6
1.3
1
reference
Symbol
V
IN
I
Q
I
Q
I
SHDN
V
FB
I
FB
f
OSC
V
IN
= 3.6V
V
IN
=2.7V-5.5V FLASH=GND,
1X Mode I
LOAD
=100uA
FLASH = High, 2x mode
V
EN
= 0V, V
IN
=5.5V
FLASH = V
IN
, R
SET
= 68kΩ
FLASH = GND
V
FB
= 0.3V
2.2
0.5
3
0.4
0.7
187
45
207
50
Conditions
Min.
2.7
0.3
2
1
227
55
1
Typ.
Max.
5.5
Units
V
mA
mA
uA
mV
mV
uA
MHz
Ω
Ω
V
V
uA
us
o
typical values at +25℃，unless
C
S
Will Semiconductor Ltd.
5
Dec, 2014 - Rev. 1.1
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