ACT6305 [ACTIVE-SEMI]
Low Input High Efficiency Synchronous Step-Up DC/DC Converter; 低投入高效率同步升压型DC / DC转换器
| 型号： | ACT6305 |
| 厂家： | 
ACTIVE-SEMI, INC |
| 描述： | Low Input High Efficiency Synchronous Step-Up DC/DC Converter |
| 文件： | 总9页 (文件大小：426K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
ACT6305
Rev0, 13-May-08
Low Input High Efficiency
Synchronous Step-Up DC/DC Converter
FEATURES
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.
• 1V Typical Startup Voltage
• Up to 94% Efficiency
• Fully Integrated Power Stage
• Fixed 3.3V/5V or Adjustable Output Voltage
• NanoStandbyTM Shutdown Mode
• Tiny SOT23-5 Package
− RoHS Compliant Package
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.
APPLICATIONS
• Hand-Held Devices
• One to Three Cell Battery Operated Devices
• PDAs
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.
• Cellular Phones
• Digital Cameras
• GPS
TYPICAL APPLICATION CIRCUIT
Efficiency vs. Output Current
L 6.8µH
100
VOUT
VIN
LX
OUT
90
80
70
60
50
40
30
ACT6305
ENABLE
VIN = 2.4V
VIN = 5V
EN
FB
G
VIN = 3.5V
VIN = 1.2V
C1
22µF
C2
22µF
Pb-free
VOUT = 5V
0.1
1.0
100
10
1000
Output Current (mA)
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Copyright © 2008 Active-Semi, Inc.
ACT6305
Rev0, 13-May-08
ORDERING INFORMATION
PART NUMBER TEMPERATURE RANGE PACKAGE PINS PACKING METHOD TOP MARK
ACT6305UC-T
-40°C to 85°C
SOT23-5
5
TAPE & REEL
HBCA
All Active-Semi components are RoHS Compliant and with Pb-free plating unless specified differently. The
term “Pb-free” means semiconductor products that are in compliance with current RoHS (Restriction of
Hazardous Substances) standards.
PIN CONFIGURATION
FB
G
1
2
3
5
OUT
ACT6305
UC
4
LX
EN
SOT23-5
PIN DESCRIPTION
PIN NUMBER PIN NAME
PIN DESCRIPTION
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 Selection section for more information.
1
FB
2
3
G
Ground.
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.
EN
4
5
LX
Inductor Connection.
OUT
Output. ACT6305 regulates voltage at this pin. OUT also provides power to the IC.
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Copyright © 2008 Active-Semi, Inc.
ACT6305
Rev0, 13-May-08
ABSOLUTE MAXIMUM RATINGSc
PARAMETER
OUT, EN to G
VALUE
UNIT
-0.3 to 6
V
FB, LX to G
-0.3 to VOUT + 0.3
Internally Limited
0.53
V
A
Continuous LX Current
Maximum Power Dissipation (derate 5mV/°C above TA = 50°C)
W
Junction to Ambient Thermal Resistance ( θJA
Operating Junction Temperature
Storage Temperature
)
190
°C/W
°C
-40 to 150
-55 to 150
300
°C
Lead Temperature (Soldering, 10 sec)
°C
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
Minimum Operating Input Voltage
Maximum Operating Input Voltage
Startup Voltage
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX UNIT
VIN
VIN
VIN
0.6
V
5
1.18
3.4
5.15
5
V
V
ILOAD = 1mA
1
3.3
5
FB = OUT; 60mVPP Ripple
FB = G; 40mVPP Ripple
External Feedback Divider
VFB = 1.3V
3.2
4.85
2
Output Voltage
VOUT
V
Output Voltage Range
V
µA
µA
V
Quiescent Current at OUT
Shutdown Supply Current
Startup to Normal Transition Threshold
FB Feedback Voltage
IQ
17
0.1
1.85
1.180
50
34
ISD
EN = G
1
VFB
VOUT = 2V to 5V
FB = 1.3V
1.15
0.7
1.21
V
FB Input Current
nA
A
Power Switch Current Limit
Power Switch On Resistance
Synchronous Rectifier On Resistance
LX Leakage Current
ILIM
1
1.25
0.4
0.4
1
RONN
RONP
ILX = 100mA
0.19
0.21
0.1
5
Ω
ILX = -100mA
Ω
EN = G, VLX = 0V or 3.3V
µA
µs
µs
V
Maximum Switch On-Time
Minimum Switch Off-Time
EN Logic Low Threshold
EN Logic High Threshold
EN Input Current
tONMAX
tOFFMIN
VIL
3.75
0.75
6.25
1.25
0.4
1
VIH
0.6
V
1
µA
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Copyright © 2008 Active-Semi, Inc.
ACT6305
Rev0, 13-May-08
TYPICAL PERFORMANCE CHARACTERISTICS
(Typical Application Circuit, L = 6.8µH, C1 = 22µF ceramic, C2 = 22µF ceramic, unless otherwise specified.)
Efficiency vs. Output Current
Efficiency vs. Constant Current
100
90
100
90
80
80
VIN = 2.4V
VIN = 5V
VIN = 1.2V
70
60
50
40
30
70
60
50
40
30
VIN = 3.5V
VIN = 1.2V
VIN = 1.8V
VIN = 2.4V
VOUT = 5V
FB = G
VOUT = 3.3V
FB = OUT
0.1
1
10
100
1000
0.1
1.0
100
10
1000
Constant Current (mA)
Output Current (mA)
Efficiency vs. Constant Current
Efficiency vs. Constant Current
100
90
100
90
80
70
60
50
80
VIN = 3.5V
VIN = 2.4V
VIN = 5V
VIN = 2.4V
70
60
VIN = 1.2V
VIN = 1.8V
VIN = 1.2V
50
40
30
VOUT = 5V
FB = G
L = 4.7µH
C1 = 10µF
VOUT = 3.3V
FB = OUT
L = 4.7µH
C1 = 10µF
40
30
0.1
1
10
100
1000
0.1
1
10
100
1000
Constant Current (mA)
Constant Current (mA)
Startup Voltage vs. Constant Resistance Load
Startup Voltage vs. Constant Resistance Load
2.00
2.00
1.75
1.50
1.25
1.00
1.75
1.50
1.25
1.00
0.75
0.5
0.75
0.5
VOUT = 3.3V
FB = OUT
VOUT = 5V
FB = G
0
50
0
200
100
150
200
50
100
150
Current Load at 5V (mA)
Current Load at 3.3V (mA)
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Copyright © 2008 Active-Semi, Inc.
ACT6305
Rev0, 13-May-08
TYPICAL PERFORMANCE CHARACTERISTICS CONT’D
(Typical Application Circuit, L = 6.8µH, C1 = 22µF ceramic, C2 = 22µF ceramic, unless otherwise specified.)
Startup Voltage vs. Temperature
Maximum On-Time vs. Temperature
1.5
1.0
6.5
5.5
0.5
4.5
-40
-20
0
20
40
60
80
100
120
-40
-20
0
20
40
60
80
100
120
Temperature (°C)
Temperature (°C)
Quiescent Supply Current vs. Temperature
Minimum Off-Time vs. Temperature
1.5
1.4
25
20
1.3
1.2
1.1
1.0
15
10
5
0
-40
-20
0
20
40
60
80
100
120
-40
-20
0
20
40
60
80
100
120
Temperature (°C)
Temperature (°C)
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Copyright © 2008 Active-Semi, Inc.
ACT6305
Rev0, 13-May-08
TYPICAL PERFORMANCE CHARACTERISTICS CONT’D
(Typical Application Circuit, L = 6.8µH, C1 = 22µF ceramic, C2 = 22µF ceramic, unless otherwise specified.)
Light Load Operation for Low ESR COUT
Medium Load Operation for Low ESR COUT
VOUT = 5V
VOUT = 5V
IN = 1.2V
LOAD = 150mA
VIN = 1.2V
V
I
ILOAD = 5mA
CH2
CH1
CH2
CH1
CH1: VLX, 2.00V/div
CH2: VOUT, 100mV/div
TIME: 100µs/div
CH1: VLX, 2.00V/div
CH2: VOUT, 100mV/div
TIME: 2.50µs/div
Heavy Load Operation for Low ESR COUT
Medium Load Operation for Low ESR COUT
VOUT = 5V
VOUT = 5V
VIN = 3.6V
VIN = 2.4V
ILOAD = 500mA
ILOAD = 300mA
CH2
CH1
CH2
CH1
CH1: VLX, 2.00V/div
CH2: VOUT, 50mV/div
TIME: 2.50µs/div
CH1: VLX, 2.00V/div
CH2: VOUT, 100mV/div
TIME: 2.50µs/div
Light Load Operation for Low ESR COUT
Medium Load Operation for Low ESR COUT
VOUT = 3.3V
VOUT = 3.3V
VIN = 1.2V
VIN = 1.8V
ILOAD = 50mA
ILOAD = 400mA
CH2
CH1
CH2
CH1
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
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Copyright © 2008 Active-Semi, Inc.
ACT6305
Rev0, 13-May-08
FUNCTIONAL BLOCK DIAGRAM
OUT
LOW INPUT
START UP
EN
REFERENCE
VREF
1µs
ONE -SHOT
SET
LATCH Q
RESET
5µs
ONE -SHOT
DRIVER
–
LX
+
VREF
ERROR
COMPARATOR
–
FEEDBACK
SELECT
+
–
FB
CURRENT LIMIT
COMPARATOR
G
Light Load Operation
FUNCTIONAL DESCRIPTION
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.
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.
Low Voltage Startup
Main Control Loop
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.
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.
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.
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Copyright © 2008 Active-Semi, Inc.
ACT6305
Rev0, 13-May-08
Board Layout
APPLICATIONS INFORMATION
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.
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.
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.
Table 1:
Output Voltage Programming
FB = OUT
FB = G
VOUT = 3.3V
VOUT = 5V
FB connect to resistive
divider
VOUT = 1.18V (1 + RFB1/RFB2)
Figure 1:
Output Voltage Setting
VOUT
OUT
CFF
ACT6305
RFB1
FB
RFB2
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.
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Copyright © 2008 Active-Semi, Inc.
ACT6305
Rev0, 13-May-08
PACKAGE OUTLINE
SOT23-5 PACKAGE OUTLINE AND DIMENSIONS
D
DIMENSION IN
MILLIMETERS
DIMENSION IN
INCHES
θ
SYMBOL
b
0.2
MIN
1.050
0.000
1.050
0.300
0.100
2.820
1.500
2.650
MAX
1.250
0.100
1.150
0.400
0.200
3.020
1.700
2.950
MIN
0.041
0.000
0.041
0.012
0.004
0.111
0.059
0.104
MAX
0.049
0.004
0.045
0.016
0.008
0.119
0.067
0.116
A
A1
A2
b
c
D
c
e
E
e1
E1
e
0.950 TYP
0.037 TYP
e1
L
1.800
2.000
0.071
0.079
0.700 REF
0.028 REF
L1
θ
0.300
0°
0.600
8°
0.012
0°
0.024
8°
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 their applications. Active-Semi products are not intended or authorized 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. For more information on this and other products, contact
sales@active-semi.com or visit http://www.active-semi.com. For other inquiries, please send to:
1270 Oakmead Parkway, Suite 310, Sunnyvale, California 94085-4044, USA
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Copyright © 2008 Active-Semi, Inc.
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