Datasheet AIC3643GG6, AIC3643GK6 Datasheet (AiC) [ru]

Ω

AIC3643

Built-in OVP White LED Step-Up Converter

 FEATURES

Built-In Open Circuit Protection



Over Voltage Protection



Efficiency Up to 83% at VIN=4.2V, 3LEDs,



I

=20mA

LED

1.2MHz Fixed Switching Frequency



Drives Up to 5LEDs in series



2.5V to 5.5V Input Voltage



Low Supply Current: 150μA



Matches LED Current



Requires Tiny Inductor and Capacitors



TSOT-23-6, and SOT-23-6 Packages



 DESCRIPTION

AIC3643 is a current-mode pulse-width­modulation (PWM), step-up DC/DC converter
designed to drive white LEDs with a constant
current to provide backlight in hand-held devices.
Series connection of LEDs provides identical
LED currents resulting in uniform brightness.
This configuration eliminates the need of ballast
resistors. The built-in open load protection
prevents the damage resulting from an open
circuit condition. Also low 100mV feedback
voltage minimizes power loss in the current
setting resistor for better efficiency.

 APPLICATIONS

Cellular Phones



PDAs



DSCs



Handheld Devices



White LED Display Backlighting



AIC3643 is a step-up PWM converter, which
includes an internal N-channel MOSFET switch
for high efficiency. The high switching frequency,

1.2MHz, allows the use of tiny external
components.

TYPICAL APPLICATION CIRCUIT



3.0~4.2V

C1
1μF

L1: GTSD31-6R8M, GOTREND
D1: SS0540, PAN JIT
C1: JMK107BJ105KA, TAIYO YUDEN
C2: GRM21BR61C335K, MURATA

L

6.8μH

VIN
SHDN
GND

AIC3643

SW

OVP

FB

Fig. 1 Li-Ion Powered Driver for Three White LEDs

D1

RFB
5

C2

3.3μF

20mA

AIC3643 is available in a space-saving TSOT­23-6, and SOT-23-6 packages.

90

85

80

75

70

Efficiency (%)

65

60

0 5 10 15 20 25 30

VIN=4.2V

LED Current (mA)

VIN=3.6V

VIN=3V

3 LEDs, 6.8μH
L1: GTSD31-6R8M, GOTREND
D1: SS0540, PAN JIT
Test Circuit refer to Fig.1

Analog Integrations Corporation Si-Soft Research Center DS-3643G-01 20090820
3A1, No.1, Li-Hsin Rd. I, Science Park, Hsinchu 300, Taiwan, R.O.C.

TEL: [phone] FAX: [phone] www.analog.com.tw

1

A

AIC3643

ORDERING INFORMATION



IC3643XXX XX

PIN CONFIGURATION

PACKING TYPE
TR: TAPE & REEL
BG: BAG

PACKAGE TYPE
G6: SOT-23-6
K6: TSOT-23-6

G: Green Package

Example: AIC3643GG6TR



in SOT-23-6 Green Package &
Tape & Reel Packing Type

SOT-23-6
TSOT-23-6
FRONT VIEW

OVP

5

2

GNDSW

SHDN

4

3

FB

VIN

6

3643G/3643K

1

Note: Pin1 is determined by orienting

the package marking as shown.

 Marking

Part No. Marking

AIC3643GG6 3643G
AIC3643GK6 3643K

2

AIC3643

ABSOLUTE MAXIMUM RATINGS



Input Voltage (VIN) 6V
SW Voltage
FB Voltage

SHDN

OVP Voltage
Operating Temperature Range
Storage Temperature Range
Maximum Junction Temperature
Lead Temperature (Soldering, 10 sec)

Thermal Resistance Junction to Case SOT-23-6
TSOT-23-6
Thermal Resistance Junction to Ambient SOT-23-6
TSOT-23-6

Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.

Voltage 6V

–40°C to 85°C

–65°C to 150°C

33V

6V

34V

150°C

260°C
115°C/W
115°C/W

250°C/W
250°C/W

3

AIC3643

ELECTRICAL CHARACTERISTICS



(V

=1.5V, VIN=3V, TA=25°C, unless otherwise specified.) (Note 1)

SHDN

PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT

Operating Voltage VIN 2.5 5.5 V

Switching 1 3 mA

Supply Current IIN

Non switching 150 270
V

= 0V 0.1 1.0

SHDN

ERROR AMPLIFIER

V

Feedback Voltage
FB Input Bias Current

90 100 110 mV

FB

I

FB

V

FB

=100mV

1 nA

OSCILLATOR

Switching Frequency f

0.8 1.2 1.6 MHz

OSC

Maximum Duty Cycle D 91 94 %

μA

POWER SWITCH

SW ON Resistance R
Switch Leakage Current I

DS(ON)

SW(OFF)VSW

1.4 2.5 Ω
=33V 0.1 1 μA

Switch Current Limit IIL 0.65 1 A

CONTROL INPUT

SHDN Voltage High V

SHDN

Voltage Low V

ON 1.5 V

IH

OFF 0.3 V

IL

OVER VOLTAGE PROTECTION

OVP Input Resistance R
OVP Threshold V

0.8 1.2 1.6 MΩ

OVP

1V Hysteresis typical 22 28 32 V

OVP

Note 1: Specifications are production tested at TA=25°C. Specifications over the -40°C to 85°C operating

temperature range are assured by design, characterization and correlation with Statistical Quality
Controls (SQC).

4

AIC3643

 TYPICAL PERFORMANCE CHARACTERISTICS

200

FB=V

190

180

170

160

150

140

130

Supply Current (μA)

120

110

100

2.5 3.0 3.5 4.0 4.5 5.0 5.5

Fig. 2 Supply Current vs. Supply Voltage Fig. 3 Supply Current vs. Supply Voltage

IN

Non-Switching

Supply Voltage (V)

1600

FB=GND

1400

1200

1000

Supply Current (μA)

800

2.5 3.0 3.5 4.0 4.5 5.0 5.5

Supply Voltage (V)

Switching

1.7

1.6

1.5

1.4

1.3

(Ω)

1.2

DS-ON

R

1.1

1.0

0.9

0.8

2.53.03.54.04.55.05.5

Fig. 4 R

1.6

1.5

1.4

1.3

1.2

1.1

1.0

Switching Frequency (MHz)

0.9

0.8

-40-200 20406080

100

VIN=3.6V; L=6.8μH
C

=1μF; C

500Hz

=3.3μF

OUT

2kHz

1kHz

100Hz

200Hz

SHDN PIN PWM Duty (%)

Temperature (oC)

IN

80

3LEDs

60

(%)

LEDMAX

/I

40

LED_DUTY

I

20

0

0 102030405060708090100

Supply Voltage (V)

vs. Supply Voltage Fig. 5 Dimming Control by Shutdown Pin

DS_ON

Temperature (oC)

110

108

106

104

102

100

98

Feedback Voltage (mV)

96

-40-200 20406080

Fig. 6 Switching Frequency vs. Temperature Fig. 7 Feedback Voltage vs. Temperature

5

AIC3643

 TYPICAL PERFORMANCE CHARACTERISTICS (Continued)

24

23

22

LED Current (mA)

21

20

-40-200 20406080

VIN=4.2V

VIN=5.5V

VIN=3V

VIN=2.5V

Temperature (oC)

VIN=3.6V

V

, 2V/div

SHDN

I

, 200mA/div

INDUCTOR

V

, 2V/div

OUT

VIN=3V; 3LEDs; L=6.8μF; C

=3.3μF; I

OUT

LED

=20mA

Fig. 8 LED Current vs. Temperature Fig. 9 Start Up from Shutdown

V

, 5V/div

SW

, 200mA/div

I

INDUCTOR

Output Ripple, 50mV/div

VIN=3.6V; 3LEDs; L=6.8μF; C

OUT

=3.3μF; I

LED

=20mA

90

85

80

75

70

Efficiency (%)

65

60

0 5 10 15 20 25 30

VIN=4.2V

VIN=3.6V

VIN=3V

3 LEDs, 6.8μH
L1: GTSD31-6R8M, GOTREND
D1: SS0540, PAN JIT
Test Circuit refer to Fig.1

LED Current (mA)

Fig. 10 Operation Waveform Fig. 11 3LEDs Efficiency vs. LED Current

90

85

80

75

70

Efficiency (%)

65

60

0 5 10 15 20 25 30

VIN=4.2V

VIN=3V

4 LEDs, 6.8μH
L1: GTSD31-6R8M, GOTREND
D1: SS0540, PAN JIT
Test Circuit refer to Fig.1

LED Current (mA)

VIN=3.6V

90

85

VIN=4.2V

80

75

70

Efficiency (%)

65

60

0 5 10 15 20 25 30

VIN=3V

5 LEDs, 6.8μH
L1: GTSD31-6R8M, GOTREND
D1: SS0540, PAN JIT
Test Circuit refer to Fig.1

VIN=3.6V

LED Current (mA)

Fig. 12 4LEDs Efficiency vs. LED Current Fig. 13 5LEDs Efficiency vs. LED Current

6

AIC3643



BLOCK DIAGRAM

OVP

100mV

VIN

FB

VREF

+

-

Error
AMP

28V

RC
CC

Over Voltage
Comparator

+

-

+

­PWM

Comparator

Slope

Compensation

Current AMP.

PWM/PFM

Control

Control

Logic

1.2MHz

Oscillator

+

-

SHDN

SW

M1

Driver

RS

GND



PIN DESCRIPTIONS

PIN 1: SW - Switch pin. Connect

inductor/diode here. Minimize
trace area at this pin to reduce
EMI.

PIN 2: GND - Ground pin. Tie directly to local

ground plane.

PIN 3: FB - Feedback pin. Reference

voltage is 100mV. Connect
cathode of lowest LED and
resistor here. Calculate resistor
value to obtain LED current
according to the formula:

R

= 100mV/I

FB

LED

PIN 4:

SHDN

PIN 5: OVP - Overvoltage protection. When

PIN 6: VIN - Power input pin. Bypass VIN to

- Shutdown pin. Tie to higher than

1.5V to enable device, 0.3V or
less to disable device.

VOUT is greater than 28V, the
internal MOSFET turns off.

GND with a capacitor sitting as
close to VIN as possible.

7

AIC3643

APPLICATION INFORMATION



Inductor Selection

A 6.8μH inductor is recommended for most
AIC3643 applications. Although small size and
high efficiency are major concerns, the inductor
should have low core losses at 1.2MHz and low
DCR (copper wire resistance). It is important to
ensure the inductor saturation current exceeding
the peak inductor current in application to prevent
core saturation. For CCM (Continuous Conduction
Mode) operation, the peak inductor current can be
calculated from:

DV

⋅

II

()

MAXINPEAK

=

+=

OSC

⋅

VI

OUT)MAX(LED

⋅η

V

+

)MIN(IN

)MAX()MIN(IN

Lf2

⋅×

DV

⋅

)MAX()MIN(IN

Lf2

⋅×

OSC

Capacitor Selection

The small size of ceramic capacitors makes them
ideal for AIC3643 applications. X5R and X7R
types are recommended because they retain their
capacitance over wider ranges of voltage and
temperature than other types, such as Y5V or
Z5U. 1

μF input capacitor with 3.3μF output

capacitor are sufficient for most AIC3643
applications.

Diode Selection

Schottky diodes, with their low forward voltage
drop and fast reverse recovery, are the ideal
choices for AIC3643 applications. The forward
voltage drop of an Schottky diode represents the
conduction losses in the diode, while the diode
capacitance (C

T or CD) r epresents the switching

losses. For diode selection, both forward voltage
drop and diode capacitance need to be
considered. In addition, the rating of selected
Schottky diode should be able to handle the
output voltage and the maximum peak diode
current.

LED Current Control

LED current is controlled by feedback resistor
(R

in Figure 1). The feedback reference voltage

FB

is 100mV. The LED current is 100mV/R

FB

. In

order to have accurate LED current, precision
resistors are preferred (1% recommended). The
formula for R

R =

FB

selection is shown below.

FB

mV100

I

LED

Open-Circuit Protection

In the cases of output open circuit, when the LEDs
are disconnected from the circuit or the LEDs fail,
the feedback voltage will be zero. AIC3643 will
then switch to a high duty cycle resulting in a high
output voltage, which may cause SW pin voltage
to exceed its maximum 33V rating. Connect built­in OVP (Over Voltage Protection) pin to output
terminal to prevent the damage resulting from an
open circuit condition.

Dimming Control

There are three different ways of dimming control
circuits as follows:

1. Using a PWM signal

PWM brightness control provides the widest
dimming range by pulsing the LEDs on and off at
full and zero current, respectively. The change of
average LED current depends on the duty cycle of
the PWM signal. Typically, a 0.1kHz to 2kHz
PWM signal is used. Two applications of PWM
dimming with AIC3643 are shown in Figure 14
and Figure 15. One, as Figure 14, uses PWM
signal to drive
control. The other, as Figure 15, employs PWM
signal going through a resistor to drive FB pin. If
the

SHDN pin is used, the increase of duty cycle

results in LED brightness enhancement. If the FB
pin is used, on the contrary, the increase of duty
cycle will decrease its brightness. In this
application, LEDs are dimmed by FB pin and
turned off completely by

2. Using a DC Voltage

For some applications, the preferred method of a
dimming control uses a variable DC voltage to
adjust LED current. The dimming control using a
DC voltage is shown in Figure 16. With a V

SHDN pin directly for dimming

SHDN.

DC

8

μ

AIC3643

ranging from 0V to 5V, the selection of resistors in
Figure 16 results in dimming control of LED
current from 20mA to 0mA, respectively.

3. Using a Filtered PWM Signal

Filtered PWM signal can be considered as an
adjustable DC voltage. It can be used to replace
the variable DC voltage source in dimming
control. The circuit is shown in Figure 17.

Layout Consideration

In order to ensure a proper operation of AIC3643,
the following points should be managed
comprehensively.

1. The input capacitor and V

should be placed

IN

VIN

C1
1μF

PWM

6.8μH

VIN

SHDN
GND

AIC3643

L

SW
OVP

FB

as close as possible to each other to reduce
the input ripple voltage.

2. The output loop, which is consisted of the
inductor, the internal power switch, the
Schottky diode and the output capacitor,
should be kept as small as possible.

3. The routes with large current should be kept
short and wide.

4. Logically the large current on the converter
should flow at the same direction.

5. The FB pin should be connected to the
feedback resistors directly and the route
should be away from the noise sources.

D1

SS0540

C2

3.3μF

R

FB

5Ω

Fig. 14 Dimming Control with a PWM Signal

V

IN

C1
1μF

6.8

VIN

SHDN
GND

AIC3643

L

SW

OVP

FB

PWM

D1

SS0540

R2
49K

R1

1K

R
5Ω

C2

3.3μF

FB

Fig. 15 Dimming Control Using a PWM Signal

9

μ

μ

Ω

Ω

AIC3643

V

IN

C1
1μF

L

6.8

H

SWVIN

OVPSHDN

D1

SS0540

C2

3.3

F

AIC3643

FB

V

DC

0~5V

R2

49K

R1

1K

R
5Ω

FB

GND

Fig. 16 Dimming Control Using a DC Voltage

VIN

C1

1μF

L

6.8μH

OVPSHDN

AIC3643

SWVIN

FBGND

PWM

Fig. 17Dimming Control Using a Filter PWM Signal

D1

SS0540

R3

5.1K

R2
49K

C3

0.1μF

R1

1K

C2

3.3μF

R

FB

5Ω

APPLICATION EXAMPLE



3.0~4.2V

C1
1μF

Fig. 18 Six White LEDs Application in Li-Ion Battery

L

6.8μH

VIN

SHDN

GND

AIC3643

SW

OVP

FB

D1

SS0540

C2

3.3μF

20mA

R

FB

5

R1
5

10

AIC3643

PHYSICAL DIMENSIONS





SOT-23-6 PACKAGE OUTLINE DRAWING

AA

D

e

e1

(unit: mm)

E

E1

A

A2

A1

SEE VIEW B

b

WITH PLATING

c

BASE METAL

SECTION A-A

0.25

L1

VIEW B

L

θ

GAUGE PLANE
SEATING PLANE

Note : 1. Refer to JEDEC MO-178AB.

2. Dimension "D" does not include mold flash, protrusions
or gate burrs. Mold flash, protrusion or gate burrs shall not
exceed 10 mil per side.

3. Dimension "E1" does not include inter-lead flash or protrusions.

4. Controlling dimension is millimeter, converted inch
dimensions are not necessarily exact.

S
Y
M
B
O
L

A

A1

A2

b

c

D

E

E1

e

e1

L

L1

θ

MIN.

0.95

0.05

0.90

0.30

0.08

2.80

2.60

1.50

0.30

0°

SOT-23-6

MILLIMETERS

MAX.

1.45

0.15

1.30

0.50

0.22

3.00

3.00

1.70

0.95 BSC

1.90 BSC

0.60

0.42 REF

8°

11

AIC3643



TSOT-23-6 PACKAGE OUTLINE DRAWING

D

E

E1

AA

e1

e

SEE VIEW B

b

WITH PLATING

A2

A

c

BASE METAL

SECTION A-A

A1

L

L1

VIEW B

Note : 1. Refer to JEDEC MO-193AA.

2. Dimension "D" does not include mold flash, protrusions
or gate burrs. Mold flash, protrusion or gate burrs shall not
exceed 6 mil per side.

3. Dimension "E1" does not include inter-lead flash or protrusions.

4. Controlling dimension is millimeter, converted inch
dimensions are not necessarily exact.

0.25

GAUGE PLANE
SEATING PLANE

θ

S

Y
M
B

O
L

A

A1

A2

b

c

D

E

E1

e

e1

L

L1

θ

MILLIMETERS

MIN.

-

0

0.70

0.30

0.08

2.80

2.60

1.50

0.30

0°

TSOT-23-6

MAX.

1.00

0.10

0.90

0.50

0.22

3.00

3.00

1.70

0.95 BSC

1.90 BSC

0.60

0.60 REF

8°

12

AIC3643

Note:

Information provided by AIC is believed to be accurate and reliable. However, we cannot assume responsibility for use of any
circuitry other than circuitry entirely embodied in an AIC product; nor for any infringement of patents or other rights of third parties
that may result from its use. We reserve the right to change the circuitry and specifications without notice.

Life Support Policy: AIC does not authorize any AIC product for use in life support devices and/or systems. Life support devices or
systems are devices or systems which, (I) are intended for surgical implant into the body or (ii) support or sustain life, and whose
failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reaso nably expected
to result in a significant injury to the user.

13