2007. 8. 22 1/6Revision No : 1
SEMICONDUCTOR
TECHNICAL DATA
KAC3305DN
Analog CMOS Integrated Circuits
700mA White LED Regulating Charge Pump for
Camera Flashes and Movie Lights
The KAC3305DN is charge pumps drive white LEDs, including camera
strobes, with regulated current up to 700mA. The very low open-loop
output resistance allows high flash brightness, even from a low battery
input voltage. The adaptive 1×/2×regulating charge pump operation
provides high efficiency while in movie mode or backlighting. Fast
switching allows the use of tiny external components. The KAC3305DN
use an external resistor to set the full-scale LED current.
Features
·Up to 700mA Output Drive Capability
·Current Regulation for Flash
·2.7V to 5.5V Supply voltage Range
·PWM Dimming Control
·Soft-Start Limits Inrush current
·Over Voltage Protection on Output
·Low Shutdown Current
·Thermal Shutdown Protection
8
Top View Bottom View
Side View
TDFN-8
MILLIMETERS
C
C
E
E
F
F
J
I
I
J
G
G
H
H
D
D
A
B
A
A
B
DIM
1.950 Ref
0.3 0.05
+
_
0.4 0.05
+
_
1.6 0.05
+
_
0.65
3.0 0.1
+
_
2.3 0.05
+
_
0.203 0.008
+
_
0.0 ~ 0.05
0.75 0.05
+
_
1
5
4
EN1
EN2 GND
CP FB
CN VIN
VOUT
8
1
45
TDFN-8
TOP VIEW
GND
FB
EN
CP Rs
CN
4.7
µ
F
10
µ
F
2.7V to 5.5V
KAC3305DN
VOUT
1
µ
F
VIN
OFF ON
Typical operating Circuit
Pin Configuration
Applications
·White LED Flashes Strobes, and Movie Lights LCD Backlighting
·Camera Phones, Cell Phones, and Smart Phones, PDAs, Digital Cameras, and camcorders
·Generic Lighting Flash, and Strobo applications
2007. 8. 22 2/6Revision No : 1
KAC3305DN
CP CN
VOUT
EN1
EN2
GND
FB
VIN Charge Pump ( 1, 2)
Soft Start
OSC
(1MHz) TSD
OVP
+
REFERENCE
CONTROL
3
2
6
7
8
1
4
5
Block Diagram
Pin Descriptions
Pin Name Function
1EN1 Current and Shutdown Control Input
2CP Positive terminal of switched capacitor
3CN Negative terminal of switched capacitor
4EN2 Current and Shutdown Control Input
5GND Ground.
6VIN Power supply voltage Input
7FB Feedback Input for the Current Control
8VOUT Output of the charge pump
2007. 8. 22 3/6Revision No : 1
KAC3305DN
Electrical Characteristics
(VIN = 3.6V, CIN=10μF, C=1μF, COUT=4.7μF, Ta= 25℃, unless otherwise noted.)
Parameter Symbol Conditions Min Typ Max Units
Input Supply voltage VIN 2.7 - 5.5 V
Supply Current IIN no load - 1 2 mA
Shutdown Supply Current ISHUT EN1=EN2=GND - - 1 μA
Soft Start time tsoft - 0.3 - ms
OUT Overvoltage Protection VOVP - 5.3 - V
FB Regulation Voltage (VOUT-VFB) VReg(FB) EN1=EN2=VIN 270 300 330 mV
Maximum OUT Current IOUT VLED=3.8V 500 700 - mA
Open Loop OUT Resistance ROUT
×1 mode - 1 - Ω
×2 mode - 4.5 - Ω
OUT Internal Pulldown in Shutdown EN1=EN2=GND - 5 - kΩ
Switching Frequency FOSC - 1 - MHz
EN Logic High Voltage VEN_IH VIN=2.7V to 5.5V 1.4 - - V
EN Logic Low Voltage VEN_IL VIN=2.7V to 5.5V - - 0.4 V
Logic Input Current IEN VEN=0V to 5.5V - - 1 μA
Thermal Shutdown Threshold TSD - 150 - ℃
Characteristics Symbol Rating Units
Input supply voltage VIN -0.3 to +6.0 V
Input pin EN1, EN2 -0.3 to (VIN +0.2) V
Maximum Power Dissipation, (＠Ta=25℃)PD1.6 W
Thermal Resistance ΘJA 62.43 ℃/W
Operating Ambient Ta -40 to +85 ℃
Junction Temperature Range Tj150 ℃
Storage Temperature Range Tstg -65 to +150 ℃
Lead Temperature TLEAD 300 ℃
Absolute Maximum Ratings
2007. 8. 22 4/6Revision No : 1
KAC3305DN
Application Information
•Output Current
The KAC3305DN is designed to deliver 200mA of continuos
current and up to 700mA of pulsed current(about 500ms).
The charge pump switching frequency is approximately
1MHz, enabilng the use of small external flying capacitor.
••Mode Switching
The KAC3305DN has two modes of operation to control the
output current : the 1×mode and 2×mode. When VIN is
greater than VOUT, the KAC3305DN regulate the current
through Rs. As VIN decreases and detects a dropout condition,
the 2×charge pump starts boosting the output to maintain
the regulation current.
••Shutdown (EN1=EN2=Low)
When voltage of the ENABLE pin goes under 0.4V, the
KAC3305DN enter the shutdown mode. In shutdown mode,
input current of IC go to zero and there are no current
between output capacitors and transfer capacitor.
••Soft-Start
To limit excessive inrush current at turn-on, the KAC3305DN
employs built-in soft-start circuitry. When starting up with an
output voltage that is not near the input voltage, the output
capacitor and flying capacitor are charged directly from the
input until the output voltage approaches the input voltage.
Soft-start is achieved a period of approximately 300μs. If
detects a dropout condition, the KAC3305DN automatically
switches to the 2×mode soft-start.
••Short protection
If output is shorted to ground, output current is limited until
VOUT exceeds 2.3V.
••Overvoltage Protection
The KAC3305DN has over voltage protection. If the output
voltage rises above the 5.3V threshold, the over voltage
protection shuts off all of the output switches to prevent the
output voltage from rising further.
••Thermal Protection
When the temperature of the KAC3305DN rises above 150
℃, the over temperature protection circuitry turns off the
output switches to prevent damage to the device. If the
temperature drops back down below 110℃, the part
automatically recovers.
••Setting the Output Current
The output regulation current is set by Rs by the equation :
Rs=(VOUT-VFB)/IOUT
Where IOUT is the output current and (VOUT-VFB) is the
reference voltage.
The resistor power obtained in the full current would be :
P=(VOUT-VFB)·IOUT＝300ｍV·700ｍA=210ｍW
For this application, the over 210mW resistor is recom-
mended.
••Capacitor Selection
To reduce noise and ripple, it is recommended that low
equivalent series resistance(ESR) ceramic capacitors be used
for both CIN and COUT. Tantalum and aluminum capacitors
are not recommended because of their high ESR. The flying
capacitors control the strength of the charge pump. In order to
achieve the rated output current it is necessary to have at least
1μF of actual capacitance.
Ceramic capacitors with X5R or X7R temperature grade are
recommended for most applications.
••Power Efficiency
To calculate the power efficiency of a white LED driver chip,
the LED power should be compared to the input power. The
difference between these two numbers represents lost power
whether it is in the charge pump or the current sources. The
power efficiency is given by
η= PLED/PIN=(VLED·ILED)/(VIN·2·ILED)≈VLED/2·VIN
••Layout Considerations
Due to its high switching frequency and the transient currents
produced the KAC3305DN, careful board layout is necessary.
The input and output capacitors should be located as close to
the VIN and VOUT as possible to obtain best bypassing. The
flying capacitor should be located as close to the CP and CN
as possible. Connect the exposed pad to GND directly under
the IC and allow sufficient copper area for cooling
2007. 8. 22 5/6Revision No : 1
KAC3305DN
Start Up
[IOUT =700mV]
EN
IOUT : 200mA/div
VOUT : 2V/div
Input and Output Ripples in 1 Mode
Input and Output Ripples in 2 Mode
[IOUT=200mA]
Input and Output Ripples in 2 Mode
[IOUT=700mA]
VOUT : 100mV/div
VIN : 100mV/div
VOUT : 100mV/div
1µS/div, AC Coupled
40µS/div
1µS/div, AC Coupled
1µS/div, AC Coupled
VIN : 100mV/div
VOUT : 100mV/div
VIN : 100mV/div
LED Current vs. Temperature
[IOUT=200mA]
190
210
198
196
194
192
208
206
204
202
200
-15 10 35-40 8560
TEMPERATURE
( )
C
Efficiency vs. Supply Voltage
[IOUT = 700mA]
VIN (V)
3.1
20
30
70
80
90
40
60
50
10
03.5 4.3 4.73.92.7 5.55.1
Efficiency (%)
LED CURRENT (mA)
VLED = 3.5V
VLED = 4.3V
2007. 8. 22 6/6Revision No : 1
KAC3305DN
Reference Voltage vs. Temperature
295
301
303
305
299
297
-15 10 35 60-40 85
LED Current vs. Supply Voltage
[IOUT=700mA]
V
IN
(V)
V
IN
(V)
3.1
400
100
800
500
600
700
200
0
300
3.5 4.3 4.73.92.7 5.55.1
IOUT (mV)
VLED=3.5V
VLED=4.3V
R
S
(Ω)
0.5
400
100
800
500
600
700
200
0
300
1.0 2.0 2.51.50.0 3.0
LED CURRENT (mA)
VLED=3.5V
VLED=4.3V
LED Current vs. RS
Battery Current vs. Supply Voltage
[IOUT=700mA]
3.1
400
1600
800
1200
600
1400
200
0
1000
3.5 4.3 4.73.92.7 5.55.1
IIN (mV)
TEMPERATURE
( )
C
REFERENCE VOLTAGE (mV)
