Innovative PowerTM - 1 - www.active-semi.com
Copyright © 2012 Active-Semi, Inc.
Rev 3, 15-Nov-12
TYPICAL APPLICATION CIRCUIT
ACT6305
Low Input High Efficiency
Synchronous Step-Up DC/DC Converter
FEATURES
• 1V Typical Startup Voltage
• Up to 94% Efficiency
• Fully Integrated Po wer Stage
• Fixed 3.3V/5V or Adjustable Output Voltage
• NanoStandbyTM Shutdown Mode
• Tiny SOT23-5 Package
− RoHS Compliant Package
APPLICATIONS
• Hand-Held Devices
• One to Three Cell Batter y Operated Devices
• PDAs
• Cellular Phones
• Digital Cameras
• GPS
GENERAL DESCRIPTION
The ACT6305 is a high efficiency synchronous
step-up DC/DC converter that consumes just 17µA
of quiescent supply current and is capable of deliv-
ering more than 400mA output current using only
three external components. This device achieves a
typical startup voltage of just 1V, making it ideal for
applications operating from 1 or 2 alkaline cells.
This device incorporates an internal synchronous
rectifier, and achieves excellent peak efficiency of
up to 94% and features a proprietary control
scheme that ensures high efficiency over a wide
load current range.
The ACT6305 features pin-selectable output volt-
ages of 3.3V or 5V, or it can also be set externally
to any voltage between 2V and 5V. The ACT6305 is
available in a tiny SOT23-5 package.
Pb-free
Efficiency (%)
Efficiency vs. Output Current
ACT6305-001
Output Current (mA)
40
60
80
100
0.1 1.0 10 1000
30
VIN = 3.5V VIN = 1.2V
VOUT = 5V
100
VIN = 5V
50
70
90
VIN = 2.4V
ACT6305
Rev 3, 15-Nov-12
Innovative PowerTM - 2 - www.active-semi.com
Copyright © 2012 Active-Semi, Inc.
ORDERING INFORMATION
PIN DESCRIPTIONS
PIN NUMBER PIN NAME PIN DESCRIPTION
1 FB
Output Voltage Selection and Feedback Input. Connect this pin to G for VOUT = 5V, to
OUT for VOUT = 3.3V. Connect FB to a resistor divider to set the output voltage be-
tween 2V and 5V. See the Output Voltage Selecti on section for more information.
2 G Ground.
3 EN
Shutdown Input. Drive EN to OUT or to a logic high for normal operation, drive EN to
G or to a logic low to disable the regulator.
4 LX Inductor Connection.
5 OUT Output. ACT6305 regulates voltage at this pin. OUT also provides power to the IC.
PART NUMBER TEMPERATURE RANGE PACKAGE PINS
ACT6305UC-T -40°C to 85°C SOT23-5 5
PACKING METHOD
TAPE & REEL
TOP MARK
HBCA
FB
G
EN
OUT
LX
1
2
34
5
ACT6305
UC
SOT23-5
All Active-Semi components are RoHS Compliant and with Pb-free plating unless specified differently. The term “Pb-free” means semi-
conductor products that are in compliance with current RoHS (Restriction of Hazardous Substances) standards.
PIN CONFIGURATION
ACT6305
Rev 3, 15-Nov-12
Innovative PowerTM - 3 - www.active-semi.com
Copyright © 2012 Active-Semi, Inc.
ABSOLUTE MAXIMUM RATINGSc
c: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rating conditions for long periods may
affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN = 1.5V, VOUT = 3.3V, TA = 25°C, unless otherwise specified.)
PARAMETER VALUE UNIT
OUT, EN to G -0.3 to 6 V
FB, LX to G -0.3 to VOUT + 0.3 V
Continuous LX Current Internally Limited A
Maximum Power Dissipation (derate 5mV/°C above TA = 50°C) 0.53 W
Junction to Ambient Thermal Resistance ( θJA ) 190 °C/W
Operating Junction Temperature -40 to 150 °C
Storage Temperature -55 to 150 °C
Lead Temperature (Soldering, 10 sec) 300 °C
PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT
Minimum Operating Input Voltage VIN 0.6 V
Startup Voltage VIN I
LOAD = 1mA 1 1.18 V
Output Voltage VOUT
FB = OUT; 60mVPP Ripple 3.2 3.3 3.4
FB = G; 40mVPP Ripple 4.85 5 5.15
Output Voltage Range External Feedback Divider 2 5 V
Quiescent Current at OUT IQ V
FB = 1.3V 17 34 µA
Shutdown Supply Current ISD EN = G 0.1 1 µA
Startup to Normal Transition Threshold 1.85 V
FB Feedback Voltage VFB V
OUT = 2V to 5V 1.15 1.180 1.21 V
FB Input Current FB = 1.3V 50 nA
Power Switch Current Limit ILIM 0.7 1 1.25 A
Power Switch On Resistance RONN I
LX = 100mA 0.19 0.4 Ω
Synchronous Rectifier On Resistance RONP I
LX = -100mA 0.21 0.4 Ω
LX Leakage Current EN = G, VLX = 0V or 3.3V 0.1 1 µA
Maximum Switch On-Time tONMAX 3.75 5 6.25 µs
Minimum Switch Off-Time tOFFMIN 0.75 1 1.25 µs
EN Logic Low Threshold VIL 0.3 V
EN Logic High Threshold VIH 0.6 V
EN Input Current 1 µA
V
Maximum Operating Input Voltage VIN 5 V
ACT6305
Rev 3, 15-Nov-12
Innovative PowerTM - 4 - www.active-semi.com
Copyright © 2012 Active-Semi, Inc.
TYPICAL PERFORMANCE CHARACTERISTICS
(Typical Application Circuit, L = 6.8µH, C1 = 22µF ceramic, C2 = 22µF ceramic, unless otherwise specified.)
Efficiency (%)
Efficiency vs. Constant Current
ACT6305-002
Constant Current (mA)
0.1 1 10 100 1000
40
50
60
70
80
90
100
30
VIN = 1.2V
VIN = 1.8V VIN = 2.4V
VOUT = 3.3V
FB = OUT
Efficiency (%)
Efficiency vs. Constant Current
ACT6305-003
Constant Current (mA)
0.1 1 10 100
1000
40
50
60
70
80
90
100
30
VIN = 2.4V
VOUT = 5V
FB = G
L = 4.7µH
C1 = 10µF
Efficiency (%)
Efficiency vs. Constant Current
ACT6305-004
Constant Current (mA)
0.1 1 10 100
1000
40
50
60
70
80
90
100
30
VIN = 1.8V
VOUT = 3.3V
FB = OUT
L = 4.7µH
C1 = 10µF
VIN = 5V
Startup Voltage (V)
Startup Voltage vs. Constant Resistance Load
ACT6305-005
Current Load at 5V (mA)
0 150 200
1.00
1.50
2.00
0.5
100
Startup Voltage (V)
Startup Voltage vs. Constant Resistance Load
ACT6305-006
Current Load at 3.3V (mA)
0 50 150
200
1.00
1.50
2.00
0.5
VOUT = 5V
FB = G
100
Efficiency (%)
Efficiency vs. Output Current
ACT6305-001
Output Current (mA)
40
60
80
100
0.1 1.0 10 1000
30
VIN = 3.5V VIN = 1.2V
VOUT = 5V
FB = G
100
VIN = 5V
50
70
90
VIN = 2.4V
VIN = 3.5V VIN = 2.4V
VIN = 1.2V
VIN = 1.2V
50
1.75
1.25
0.75
1.75
1.25
0.75 VOUT = 3.3V
FB = OUT
ACT6305
Rev 3, 15-Nov-12
Innovative PowerTM - 5 - www.active-semi.com
Copyright © 2012 Active-Semi, Inc.
-20
TYPICAL PERFORMANCE CHARACTERISTICS CONT’D
(Typical Application Circuit, L = 6.8µH, C1 = 22µF ceramic, C2 = 22µF ceramic, unless otherwise specified.)
Quiescent Supply Current vs. Temperature
ACT6305-010
ACT6305-008
Maximum On-Time vs. Temperature
Minimum Off-Time vs. Temperature
ACT6305-009
40 20 0
1.5
1.0
0.5
60 80 120
Temperature (°C)
Startup Voltage (V)
Startup Voltage vs. Temperature
ACT6305-007
100
-40 -20 40 20 0 60 80 120
Temperature (°C)
100
6.5
5.5
4.5
Maximum On-Time (µS)
-40
1.5
1.2
1.0
Minimum Off-Time (µS)
1.1
1.3
1.4
-20 40 20 0 60 80 120
Temperature (°C)
100
-40
25
10
0
Quiescent Supply Current (µA)
5
15
20
-20 40 20 0 60 80 120
Temperature (°C)
100
-40
ACT6305
Rev 3, 15-Nov-12
Innovative PowerTM - 6 - www.active-semi.com
Copyright © 2012 Active-Semi, Inc.
TYPICAL PERFORMANCE CHARACTERISTICS CONT’D
(Typical Application Circuit, L = 6.8µH, C1 = 22µF ceramic, C2 = 22µF ceramic, unless otherwise specified.)
Medium Load Operation for Low ESR COUT
ACT6305-012
CH2
CH1
CH1: VLX, 2.00V/div
CH2: VOUT, 100mV/div
TIME: 2.50µs/div
CH1: VLX, 2.00V/div
CH2: VOUT, 100mV/div
TIME: 100µs/div
CH2
ACT6305-011
Light Load Operation for Low ESR COUT
CH1
VOUT = 5V
VIN = 1.2V
ILOAD = 5mA
VOUT = 5V
VIN = 1.2V
ILOAD = 150mA
ACT6305-013
CH2
CH1
Medium Load Operation for Low ESR COUT
CH1: VLX, 2.00V/div
CH2: VOUT, 100mV/div
TIME: 2.50µs/div
VOUT = 5V
VIN = 2.4V
ILOAD = 300mA
ACT6305-014
Heavy Load Operation for Low ESR COUT
CH2
CH1
CH1: VLX, 2.00V/div
CH2: VOUT, 50mV/div
TIME: 2.50µs/div
VOUT = 5V
VIN = 3.6V
ILOAD = 500mA
Medium Load Operation for Low ESR COUT
CH2
CH1
CH2
ACT6305-015
Light Load Operation for Low ESR COUT
CH1
ACT6305-016
CH1: VLX, 2.00V/div
CH2: VOUT, 50mV/div
TIME: 25.0µs/div
CH1: VLX, 2.00V/div
CH2: VOUT, 100mV/div
TIME: 2.50µs/div
VOUT = 3.3V
VIN = 1.2V
ILOAD = 50mA
VOUT = 3.3V
VIN = 1.8V
ILOAD = 400mA
ACT6305
Rev 3, 15-Nov-12
Innovative PowerTM - 7 - www.active-semi.com
Copyright © 2012 Active-Semi, Inc.
FUNCTIONAL DESCRIPTION
As seen in the Functional Block Diagram, the
ACT6305 comprises a reference, low input startup
circuitry, feedback select, error comparator, control
logic and timers, internal power MOSFETs and cur-
rent comparators.
Main Control Loop
The ACT6305 control architecture utilizes a series
of one-shot and current sense circuits to regulate
the output voltage with a very low quiescent supply
current of just 17µA. An ON cycle begins when FB
falls below the ACT6305’s internal reference volt-
age. During an ON cycle, the N-channel power
switch is turned on to connect the LX node to
ground, transferring energy from input supply to the
inductor. The ON cycle persists or the 1A current
limit is reached. When either of these conditions
occurs, the N-channel power switch turns off and
the OFF cycle begins. During the OFF cycle, the
energy stored in the inductor is released into the
output capacitor and load through the synchronous
rectifier. Once the 1µs minimum OFF time expires,
another ON cycle begins when the FB voltage
drops below the reference voltage.
Light Load Operation
Under light load conditions, the IC automatically
enters a power-saving mode by extending the OFF
time. This reduces switching losses and allows the
ACT6305 to maintain high efficiency across a very
wide load range.
Low Voltage Startup
The ACT6305 uses proprietary start-up circuitry that
allows it to achieve very low voltage startup down to
1V. The ACT6305 remains in low voltage startup
mode until VOUT exceeds 1.85V. The ACT6305 can-
not support its full rated load current when operat-
ing in low-voltage startup mode. Care should be
taken to minimize load current during startup.
Shutdown
In shutdown mode, all internal circuits including the
power switch and the synchronous rectifier are dis-
abled, reducing quiescent supply current to less
than 1µA. Note that in shutdown mode, a DC path
from the input supply to the output still exists due to
the body diode of the synchronous rectifier.
FUNCTIONAL BLOCK DIAGRAM
OUT
LX
G
REFERENCE
FEEDBACK
SELECT
VREF
VREF
+
DRIVER
ERROR
COMPARATOR
LOW INPUT
START UP
1µs
ONE -SHOT
5µs
ONE -SHOT
SET
LATCH Q
RESET
CURRENT LIMIT
COMPARATOR
EN
FB
+
–
+
–
–
ACT6305
Rev 3, 15-Nov-12
Innovative PowerTM - 8 - www.active-semi.com
Copyright © 2012 Active-Semi, Inc.
APPLICATIONS INFORMATION
Output Voltage Selection
The ACT6305 provides fixed output voltage options
of 3.3V or 5V, or the output voltage may be ad-
justed over a 2V to 5V range by connecting an
external resistive voltage divider. When Output Volt-
age is set by external resistive voltage divider, add
a 47pF to 150pFcapacitor as feedforward capacitor
(CFF) as shown in Figure 1.
Table 1:
Output Voltage Programming
Figure 1:
Output Voltage Setting
Output Capacitor Selection
A minimum value of output capacitance is required
to maintain loop stability and normal operation of
the IC. The output capacitor value should be in the
range of 22µF to 100µF. To obtain small output rip-
ple, use a large capacitor with low ESR. Ceramic
capacitors should be used for highest performance.
If a tantalum capacitor is used, choose only low
ESR types and a smaller low ESR capacitor of
about 1µF can be connected in parallel to filter high
frequency noise.
Inductor Selection
For most applications, the inductor value should be
in the range of 4.7µH to 22µH. Smaller inductors
provide faster load transient response and have a
smaller physical size, but they also result in higher
ripple current and reduce the maximum available
output current. Choose inductors with low series
resistance to obtain the highest efficiency.
Board Layout
To reduce noise and increase efficiency, high cur-
rent traces should be wide and direct, and an ex-
tended ground plane should be used. Switching
current paths should be laid out as tightly as possi-
ble, with the inductor and input and output capaci-
tors located close to the IC in order to reduce elec-
tromagnetic radiation.
If an external resistor divider is used, place the re-
sistors very close to the FB and G pins, and keep
them away from the high switching current paths.
FB = OUT VOUT = 3.3V
FB = G VOUT = 5V
FB connect to resistive
divider VOUT = 1.18V (1 + RFB1/RFB2)
FB
ACT6305
VOUT
RFB1
RFB2
OUT CFF
ACT6305
Rev 3, 15-Nov-12
Innovative PowerTM - 9 - www.active-semi.com
Copyright © 2012 Active-Semi, Inc.
PACKAGE OUTLINE
SOT23-5 PACKAGE OUTLINE AND DIMENSIONS
D
b
E1
E
e
e1
A1
A2
A
c
LL1
0.2
θ SYMBOL DIMENSION IN
MILLIMETERS DIMENSION IN
INCHES
MIN MAX MIN MAX
A - 1.450 - 0.057
A1 0.000 0.150 0.000 0.006
A2 0.900 1.300 0.035 0.051
b 0.300 0.500 0.012 0.020
c 0.080 0.220 0.003 0.009
D 2.900 BSC 0.114 BSC
E 1.600 BSC 0.063 BSC
E1 2.800 BSC 0.110 BSC
e 0.950 BSC 0.037 BSC
e1 1.900 BSC 0.075 BSC
L 0.60REF
L1 0.300 0.600 0.012 0.024
θ 0° 8° 0° 8°
0.024REF
Active-Semi, Inc. reserves the right to modify the circuitry or specifications without notice. Users should evaluate each
product to make sure that it is suitable for th eir applicatio ns. Active-Se mi products are not inten ded or aut horized for use
as critical components in life-support devices or systems. Active-Semi, Inc. does not assume any liability arising out of
the use of any product or circuit described in this datasheet, nor does it convey any patent license.
Active-Semi and its logo are trademarks of Active-Semi, Inc. F or more info rmation on this and other products, contact
sales@active-semi.com or visit http://www.active-semi.com.
is a registered trademark of Active-Semi.
