2005. 9. 9
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SEMICONDUCTOR
TECHNICAL DATA
KAC3301QN
Analog CMOS Integrated Circuits
Revision No : 0
1X/1. 5X Fractional Charge Pump for
White LED Driver with Dimming Control
The KAC3301 is low noise constant frequency charge pump DC/DC
converter specially designed to drive up to four white LEDs with constant
current from Li-ion cell. Dual (1x/1.5x) Modes and low dropout voltage of
LED driver maximize efficiency for the white LED application over full Li-ion
battery input range. The LED current is set by the external resistor. PWM(Pulse
Width Modulation) signal can be used to control LED brightness over wide
frequency range. Various kinds of protection circuits protect your system from
every undesirable output condition.
Features
1x/1.5x dual charge pump modes with auto detection.
Excellent Power Efficiency. (more than 92% of P
MAX
)
LED current matching of 2%.
Power-down current below 1uA.(max.)
Up to 30mA/LED current capability. [V
IN
> 3.1V]
Up to 20mA/LED current capability. [V
IN
> 2.7V]
Strong to ESD. [MM:>200V, HBM:>2000V]
Low input ripple and EMI.
PWM or Analog dimming control.
2.7V to 5.5V input voltage range.
Output over-voltage protection.
Thermal shutdown protection.
Output over-current protection.
Soft start limits Inrush current.
Automatic soft-start protects IC from output short.
1MHz switching frequency.
QFN-16 package.
Applications
Cellular phones, Smart Phones, PDA, Digital Cameras, Camcorders.
MP3 player and other handheld devices with color displays operating circuit.
4.00 0.05
1
4
5
8
9
13
16
0.33 0.05
2.40 0.05
2.30 0.05
0.9 0.1
0.203 0.008
0.55 0.05
0.650BSC
0.45 0.05
R0.030 Max
0.05 Max
Pin 1
Top View
Bottom View
Side View
QFN16
MILLIMETERS
C
C
E
E
F
F
J
J
K
K
I
I
G
G
H
H
D
D
A
A
A
B
B
DIM
+
_
+
_
+
_
+
_
+
_
+
_
+
_
+
_
8
7
6
5
4
3
2
1
16
15
14
13
12
11
10
9
V
IN
R
SET
C1P V
IN
V
OUT
I
SET
NC
NC
DIM
EN
D4
D3
D2
D1
GND
C2P
C2N
C1N
H:ON L:OFF
H:ON L:OFF
1
1
1
1
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
D4
D3
D2
D1
GND
C2P
C2N
C1N
C1P
V
IN
V
OUT
I
SET
NC
NC
DIM
EN
QFN-16
TOP VIEW
Typical operating Circuit
Pin Configuration
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KAC3301QN
Revision No : 0
Soft-Start
Current Limit
Min. Vol.
Selector
Thermal Protect
Mode
Controller
OSC
(1MHz)
OVD
V
REF
(1.24V)
sw
sw
sw sw sw sw
C1P
C1N
C2P
C2N
V
OUT
LED1
LED2
LED3
LED4
GND
I
SET
DIM
EN
V
IN
+
Current Setter
Charge Pump (1 /1.5 )
Block Diagram
Pin Descriptions
Pin
Name
Function
1
EN
Chip enable input.(Shutdown at Low state)
2
DIM
PWM Dimming control input
3
NC
4
NC
5
I
SET
Reference current set.(Connecting a resistor to gorund)
Analog Dimming Control
6
V
OUT
Charge pump output
7
V
IN
Power Supply Voltage Input
8
C1P
Positive terminal of switched capacitor1
9
C1N
Negative terminal of switched capacitor1
10
C2N
Negative terminal of switched capacitor2
11
C2P
Positive terminal of switched capacitor2
12
GND
Ground
13
D1
Sinking current input for LED1
14
D2
Sinking current input for LED2
15
D3
Sinking current input for LED3
16
D4
Sinking current input for LED4
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KAC3301QN
Revision No : 0
Electrical Characteristics
(Ta=-40 to 85 , 2.7V< V
IN
< 5.5V,C1 = C2 = 1.0 . unless otherwise noted.) (note 1)
Parameter
Symbol
Conditions
Min
Typ
Max
Units
Input Supply Voltage
V
IN
2.7
-
5.5
V
Maximum LED sink current
I
LED
2.7V V
IN
(I
SET
=50 )
-
20
-
mA
3.1V V
IN
(I
SET
=75 )
-
30
-
mA
Set bias Voltage
V
SET
1.178
1.24
1.302
V
Current Ratio
I
LED
/I
SET
-
400
-
Quiescent current
I
Q
No load(V
DIM
=High).
I
SET
=12.5
-
1.0
2.0
mA
Power-down Current
I
PD
V
EN
=GND, Ta=25
-
0.1
1
I
LED
Accuracy
I
LED
_A
CC
2mA I
LED
30mA
-
5
-
%
I
LED
Matching between any other I
LED
I
LED_MAT
(Note 2)
2mA I
LED
30mA
-
2
-
%
LED regulation Voltage
V
LED
50
120
200
mV
Maximum Output Current
I
OUT
V
IN
3.1V, V
OUT
3.8V
120
140
-
mA
V
IN
2.7V, V
OUT
3.5V
80
90
-
mA
Input Current Limit
I
LIMIT
Short Condition in V
OUT
Without Softstart. (Note 3)
160
-
850
mA
Thermal Shutdown Threshold
T
SD
40
Hysteresis
-
150
-
Over-Voltage Protect
V
OVP
-
5.5
6.0
V
Hysteresis of V
OVP
V
HTY_OVP
-
0.4
-
V
Switching frequency
F
SW
-
1
-
MHz
Input Logic High
V
IH
1.3
-
-
V
Input Logic Low
V
IL
-
-
0.4
V
Note 1 : Specifications to -40
are guaranteed by design and not production tested.
I
MAX
- I
MIN
Note 2 : I
LEAD _ MAT
[%]=
100
I
MAX
+I
MIN
Note 3 : This is occurred when Pin of LED is shorted to GND, or there are ohmic short V
OUT
to GND
Maximum Ratings
Characteristics
Symbol
Rating
Units
Input supply Voltage
V
IN
-0.3 to +6.0
V
Input Pin
DIM,EN
-0.3 to (V
IN
+0.2)
V
Maximum Power Dissipation. (@Ta=25 )
P
D
2.6
W
Thermal Resistance
JA
48.22
/W
Operating Ambient
Ta
-40 to + 85
Junction Temperature
Tj
-40 to + 150
Storage Temperature
T
stg
-65 to + 150
Lead Temperature
T
LEAD
300
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KAC3301QN
Revision No : 0
Dimming :
Application Information
Output Regulation
KAC3301 maintains constant LED brightness even at very low battery voltage. For example, at 2.7V of the battery voltage KAC3301 can
maintain constant LED bright above 20mA. For better efficiency KAC3301 will be kept in 1x mode unless lowest voltage of the LED1~LED4
goes under the 50mV. Constant switching frequency & optimized duty make low input and output ripple at the 1.5x mode. Ofcourse, KAC3301
has almost no output ripple at the 1x mode.
LED Current Control
The LED current is a multiple of the current flowing out of the I
SET
pin. Set the LED current as follows:
1.24V
I
LED
= K
, K =380
R
SET
Internal high reference voltage (1.24V) helps you to choice R
SET
value of K takes low current through R
SET
. Values of R
SET
for a fixed LED
current are given in the table below.
I
LED
[mA]
30
20
15
10
5
2
1
0.5
R
SET
[ ]
15.7
23.6
31.4
47.1
94
236
471
942
RADJ
VADJ
V
OUT
VIN
EN
DIM
ISET
GND
LED1
LED2
LED3
LED4
C1P
C2P
C1N
C2N
C1P
C2P
C1N
C2N
R1
R2
RN
EN
DIM
ISET
GND
LED1
LED2
LED3
LED4
3301QN
C1P
C2P
C1N
C2N
PWM Inout
EN
DIM
ISET
GND
LED1
LED2
LED3
LED4
3301QN
3301QN
1
1
1
1
1
1
1
1
1
1
1
1
V
OUT
V
IN
V
OUT
V
IN
Method
External device
Range of "ILED"
Note
Analog
Voltage Source [V
ADJ
]
0.5mA~30mA
R
SET
volume resistor [R
ADJ
]
0.5mA~30mA
PWM
PWM Input
0.5mA~30mA
Recommend Freq.: 100Hz~20KHz.
Digital 2N bit
NMOS Switched parallel resistors
0.5mA~30mA
ANALOG
DIGITAL 2N bit
PWM
Adjustable Voltage Source method ; R
ADJ
is fixed Value (R
SET
)!
Volume resistor method : V
ADJ
is not needed! V
ADJ
=0
In the Both case I
LED
is controlled by the equation as follows;
(V
REF
-V
ADJ
)
I
LED
[ ]=380
R
ADJ
I
LED
[ ]= 0, when(V
ADJ
>V
REF
)
R
SET
= R0//R1//R2//...//RN
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KAC3301QN
Revision No : 0
Shutdown (Enable=Low)
When voltage of the ENABLE pin goes under 0.4V, KAC3301 enter the shutdown mode where input current go to zero and there are no
current between output capacitors and transfer capacitor.
Soft-Start
KAC3301 has its original soft-start function to limit inrush current at turn on. KAC3301 charges transfer capacitors and output capacitor
with a constant input current until output voltage goes to the value of (1.4
V
IN
). If output voltage reached the value of (1.4
V
IN
) or
over-voltage protection circuit is activated, LED current start to flow. But input current remains to zero until output voltage goes down to
usual output operating voltage from the discharge of LED current. At the every turn on the ENABLE and output voltage less than 25% of
the input voltage, soft-start sequence is introduced for the safety.
Short protection (various short mode)
1) short V
OUT
pin to GND pin: If output is shorted to ground, output current is limited by the soft-start which is repeated until V
OUT
remains under 25% of V
IN.
2) short LED pin to GND pin: If this occurs at the soft-start-mode or shutdown state, KAC3301 stays at soft-start-mode. Else this is done
during operating, the output current is limited by the current-limitcircuitry.
3) short V
OUT
pin to LED pin(shorted LED): There are no change but shorted LED doesn t work.
Open protection
If more than one LED is opened, output voltage is limited by over-voltage-protect circuitry. But, other LEDs work continuously without
change of the brightness.
Current limit
There could be variable short mode in the backlight system. For example, V
OUT
pin to GND or LED pin to GND or short of LEDs, etc. In
these case, large current could be flow at the output pin. KAC3301 are protected by the Thermal shutdown circuitry, but external elements
might be damaged without current limit circuitry. Current limit circuitry set you to ease to design safely.
Over-voltage protection
When a LED pin shorted to the ground or LED is opened itself, voltage of the LED terminal could be almost 0V without any concerning to
the other conditions. In this case, output voltage might be raised over IC's maximum ratings. And, then IC may be destroyed! KAC3301
maintains over voltage protection circuitry for the prohibiting output voltage over the maximum ratings.
Thermal shutdown
KAC3301 includes a thermal shutdown circuit which makes IC shutdown at 150 (typ.) and recover after IC cools by
approximately 40 .
Input Ripple
For LED drive ICs in mobile system, input ripple is more important than output ripple, because there are many other components which
have input supply terminal from battery instead of the output terminal. KAC3301 has very excellent input ripple characteristics which is
depends on the supply's impendence. You can get better input ripple characteristics, by minimizing resistance from battery to the V
IN
pin.
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