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FEATURES
* * * * * * * * * * *
ACT8309/8310/8311
Rev PrA, 24-Jan-08 Advanced Product Information - All Information Subject to Change
1.5A, PWM Step-Down DC/DCs in TDFN GENERAL DESCRIPTION
The patent-pending ACT8309/ACT8310/ACT8311 are current-mode, fixed-frequency PWM, synchronous step-down DC/DC converters that are capable of delivering 1.5A with efficiency of up to 95%. These devices operate with a fixed frequency of 1.35MHz, minimizing noise in sensitive equipment as well as optimizing both efficiency and component size and cost. These devices feature very low-resistance power MOSFET and 100% duty cycle operation, making them ideal choices for portable applications requiring a 3.0V or 3.3V rail to be generated from a Li+ battery. The ACT8311 is capable of supplying up to 1.5A of output current, while the ACT8309 and ACT8310 are capable of supplying up to 900mA and 1.2A, respectively. All three devices have adjustable output voltages that are programmable down to 1.2V. Contact Active-Semi for custom fixed output voltage availability.
Multiple Patents Pending Up to 95% High Efficiency Up to 1.5A Guaranteed Output Current (ACT8311) 1.35MHz Constant Frequency Operation Internal Synchronous Rectifier Eliminates Schottky Diode ACT8309: Up to 900mA ACT8310: Up to 1.2A ACT8311: Up to 1.5A 100% Duty Cycle Low-Dropout Operation 0.1A Shutdown Current Small TDFN33-8 Package - RoHS-Compliant
* Independent Enable/Disable Control * Minimal External Components
APPLICATIONS
* Wireless Handhelds * Portable Devices * GPS/PND equipment
SYSTEM BLOCK DIAGRAM
2.7V to 5.0V ON OFF Power-OK Output
IN EN POK
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ACT8311
SW
VOUT Up to 1.5A
Pb-free
FB
GP
G
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ORDERING INFORMATION
PART NUMBER
ACT8309NHADJ-T ACT8309NHxyz-T ACT8310NHADJ-T ACT8310NHxyz-T ACT8311NHADJ-T ACT8311NHxyz-T
ACT8309/8310/8311
OUTPUT CURRENT
0.9A 0.9A 1.2A 1.2A 1.5A 1.5A
Rev PrA, 24-Jan-08
OUTPUT VOLTAGE
Adjustable 1.2V, 1.5V, 1.8V, 2.5V, 3.0V, 3.3V Adjustable 1.2V, 1.5V, 1.8V, 2.5V, 3.0V, 3.3V Adjustable 1.2V, 1.5V, 1.8V, 2.5V, 3.0V, 3.3V
PACKAGE
TDFN33-8 TDFN33-8 TDFN33-8 TDFN33-8 TDFN33-8 TDFN33-8
PINS
8 8 8 8 8 8
TEMPERATURE RANGE
-40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C
: Fixed output voltage options are available for production subject to minimum order quantities. Contact Active-Semi for more information regarding fixed output voltage options.
PIN CONFIGURATION
IN GP IN G
1 2 3 4
8
SW EN POK FB
ACT8309 ACT8310 ACT8311
7 6 5
TDFN33-8
PIN DESCRIPTIONS
PIN
1, 3 2 4 5
NAME
IN GP G FB
DESCRIPTION
Power Input. Bypass to GP close to IC with a high quality ceramic capacitor. Power Ground. Connect to G with a short trace. Analog Ground. Connect to GP with a short trace. Feedback Node. For fixed output voltage versions, connect this pin directly to the output. For the adjustable output versions the voltage at this pin is regulated to 0.8V, connect to this pin to the center of the output feedback resistor divider for voltage setting. Open-Drain Power-OK Status Output. POK is an open-drain output which sinks current when the output voltage is less than 95% of the normal value. When the IC is disabled, POK is high impedance. Enable Input. When higher than 1.4V, this pin turns the IC on. When lower than 0.4V, this pin turn the IC off. Switch Output. Connect this pin to the switching end of the inductor.
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6 7 8
POK EN SW
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ABSOLUTE MAXIMUM RATINGS
PARAMETER
IN, SW to GP FB, EN, POK to G FB, EN, SW Voltage GP to G Continuous SW Current Junction to Ambient Thermal Resistance (JA) Maximum Power Dissipation (derate 5.3mW/C above TA = 50C) Operating Junction Temperature Storage Temperature Lead Temperature (Soldering, 10 sec)
ACT8309/8310/8311
VALUE
-0.3 to +5.5 -0.3 to +5.5 -0.3 to VIN + 0.3 -0.3 to +0.3 Internally limited 61 1.63 -40 to 150 -55 to 150 300
Rev PrA, 24-Jan-08
UNIT
V V V V A C/W W C 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.
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ELECTRICAL CHARACTERISTICS
(VIN = VEN = 3.6V, TA = 25C, unless otherwise specified.)
ACT8309/8310/8311
Rev PrA, 24-Jan-08
PARAMETER
Input Voltage Range Under Voltage Lockout Threshold Standby Supply Current Shutdown Supply Current FB Voltage
SYMBOL
VIN VUVLO
TEST CONDITIONS
VIN rising, hysteresis = 80mV VFB = 103%VFB,TYP, IOUT = 0 EN = G, VIN = 4.2V
MIN
2.7 2.35
TYP
2.5 150 0.1
MAX
5.0 2.6 310 1 0.814 0.824 +2% +3% 0.4
UNIT
V V A A V
VFB
TA = 25C -40C < TA < 85C TA = 25C -40C < TA < 85C
0.786 0.776 -2% -3%
0.80 0.80 VNOM VNOM 0.06 0.6
Output Voltage Accuracy Output Voltage Line Regulation Output Voltage Load Regulation
V %/V %
ACT8309NH Current Limit ACT8310NH ACT8311NH ACT8309NH Max Output Current ACT8310NH ACT8311NH Oscillator Frequency fSW VOUT = 80% of VOUT,NOM VFB = 0.1V ACT8309, ISW = -100mA PMOS On-Resistance RONP ACT8310, ISW = -100mA ACT8311, ISW = -100mA NMOS On-Resistance EN Logic High Threshold EN Logic Low Threshold EN Input Bias Current POK Threshold POK Output Low Voltage POK Leakage Current VOL IPOK RONN VIH VIL IEN ISW = 100mA VIN = 2.7V to 5.0V VIN = 2.7V to 5.0V VIN = 5.0V, EN = G or IN % of VOUT,NOM IPOK = 100A VPOK = 5.0V
1.1 1.4 1.75
1.3 1.7 2.1
1.8 2.2 2.8 0.9 1.2 1.5 A A
1.05
1.35 450 0.15 0.12 0.10 0.15
1.6
MHz kHz
0.234 0.192 0.165 0.26 V 0.4 V A % 0.012 0.1 V A
1.4
0.01 95 0.008 0.01
0.1
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Figure1: Functional Block Diagram
ACT8309/8310/8311
Rev PrA, 24-Jan-08
Active-Semi
ACT8309 ACT8310 ACT8311
EN IN
IN
GATE DRIVER
PWM CONTROL
SW OUT
OUT POK GP
FB
G
Figure 2: Typical Application Circuit
2.7V to 5.0V 10F
IN IN
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SW
3.3H
OUT
3.0V Up to 1.5A 22F
OUT 100k? 100k
EN
ACT8311
FB
549k? 549k 200k? 200k
POK GP G
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FUNCTIONAL DESCRIPTION
The patent-pending ACT8309/ACT8310/ACT8311 are current-mode, fixed-frequency PWM, synchronous step-down DC/DC converters that are capable of delivering up to 1.5A (ACT8311) with efficiency of up to 95%. These devices feature very lowresistance power MOSFETs and 100% duty cycle operation, making them ideal choices for portable applications requiring a 3.0V or 3.3V rail to be generated form a Li+ battery. These device operate with a fixed frequency of 1.35MHz, minimizing noise in sensitive equipment as well as optimizing both efficiency and component size and cost.
ACT8309/8310/8311
Rev PrA, 24-Jan-08
For most applications, a 22F ceramic output capacitor is recommended. Although the these regulators were designed to take advantage of the benefits of ceramic capacitors, namely small size and very-low ESR, low-ESR tantalum capacitors can provide acceptable results as well.
Inductor Selection
These devices were optimized for operation with 3.3H inductors, although inductors in the 1.5H to 4.7H range may be used. Choose an inductors with a low DC-resistance, and avoid inductor saturation by choosing inductors with DC ratings that exceed the maximum output current of the application by at least 30%.
100% Duty Cycle Operation
These devices are capable of operating at up to 100% duty cycle operation. During 100% duty cycle operation, the high-side power MOSFET is held on continuously, providing a direct connection from the input to the output (through the inductor), ensuring the lowest possible dropout voltage in batterypowered applications.
Output Voltage Setting
Figure 3 shows the feedback network necessary to set the output voltage when using adjustable output voltage options. output voltage options. Select components as follows: Set RFB2 = 200k, calculate RFB1 using the following equation:
Synchronous Rectification
The ACT8309/ACT8310/ACT8311 each feature integrated n-channel synchronous rectifiers, maximizing efficiency and minimizing the total solution size and cost by eliminating the need for external rectifiers.
V RFB1 = RFB2 OUT - 1 V FB
Where VFB is 0.8V. Figure 3: Output Voltage Setting
VOUT ACT8309/ ACT8310/ ACT8311 RFB1 FB RFB2
Soft-Start
The ACT8309/ACT8310/ACT8311 each include integrated soft-start circuitry. When enabled, the output voltage track an internal 200s soft-start ramp so that the output power up in a controlled, monotonic manner that is independent of loading.
Compensation
The ACT8309/ACT8310/ACT8311 each utilize current-mode control and a proprietary internal compensation scheme to simultaneously simplify external component selection and optimize transient performance over their full operating range. No compensation design is required, simply follow a few simple guidelines described below when choosing external components.
Enable/Disable Control
These devices may be enabled and disabled using the EN input. Drive EN to a logic-high to enable the regulator, drive EN to a logic-low to disable the regulator. When disabled, each regulator's quiescent supply current drops to less than 1A.
Capacitor Selection
The input capacitor reduces peak currents and noise induced upon the voltage source. A 10F ceramic capacitor is recommended for most applications.
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Power-OK Output (POK)
These devices feature an open-drain "Power-OK" indicator output. This output sinks current whenever the output voltage is (typically) 5% below the regulation voltage, and goes high-impedance when the output voltage is above this threshold. To generate
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a logic-level "Power-OK" signal, simply connect a pullup resistor from POK to an appropriate output voltage.
ACT8309/8310/8311
Rev PrA, 24-Jan-08
PCB Layout Considerations
High switching frequencies and large peak current make PC board layout an important part of stepdown DC/DC converter design. A good design minimizes excessive EMI on the feedback paths and voltage gradients in the ground plane, both of which can result in instability or regulation errors. Step-down DC/DCs exhibit discontinuous input current, so the input capacitors should be placed as close as possible to the IC, and avoiding the use of vias if possible. The inductor, input filter capacitor, and output filter capacitor should be connected as close together as possible, with short, direct, and wide traces. The ground nodes for each regulator's power loop should be connected at a single point in a star-ground configuration, and this point should be connected to the backside ground plane with multiple vias. For fixed output voltage options the output node for each regulator should be connected to its corresponding FB pin through the shortest possible route, while keeping sufficient distance from switching nodes to prevent noise injection. Adjustable output versions should follow the same guidelines, but additionally connect the feedback resistors to the FB pin as close to the IC as possible to minimize noise injection.
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ACT8309/8310/8311
Rev PrA, 24-Jan-08
TYPICAL PERFORMANCE CHARACTERISTICS
(VIN = VEN = 3.6V, TA = 25C, unless otherwise specified.)
ACT8309 Efficiency vs. Load Current
100 90 80 200 180 ACT8309/8310/8311-001
ACT8309 Dropout Voltage vs. Load Current
ACT8309/8310/8311-002
Dropout Voltage (mV)
160 140 120 100 80 60 40 20 0 0 100 200 300 400 VOUT = 3.0V
VOUT = 3.3V
Efficiency (%)
70 60 50 40 30 20 10 0 1 10 VOUT = 3.0V VOUT = 3.3V
VOUT = 1.8V
VOUT = 1.2V
VIN = 3.6V 100 1000 10000
500
600
700
800
900
Load Current (mA)
Load Current (mA)
ACT8310 Efficiency vs. Load Current
100 90 80 200 180 ACT8309/8310/8311-003
ACT8310 Dropout Voltage vs. Load Current
ACT8309/8310/8311-004
Dropout Voltage (mV)
VOUT = 3.3V
160 140 120 100 80 60 40 20 0 0 200 400 600 800 1000 VOUT = 3.0V
Efficiency (%)
70 60 50 40 30 20 10 0 1 10 VOUT = 3.3V VOUT = 3.0V
VOUT = 1.8V
VOUT = 1.2V
VIN = 3.6V 100 1000 10000
1200
Load Current (mA)
Load Current (mA)
ACT8311 Efficiency vs. Load Current
100 90 80 220 200 180 160 140 120 100 80 60 40 20 0 10 100 1000 10000 ACT8309/8310/8311-005
ACT8311 Dropout Voltage vs. Load Current
ACT8309/8310/8311-006
Efficiency (%)
70 60 50 40 30 20 10 0 1 VOUT = 3.3V VOUT = 3.0V VOUT = 1.8V
VOUT = 1.2V
Dropout Voltage (mV)
VOUT = 3.3V
VOUT = 3.0V
VIN = 3.6V
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4 1.5
Load Current (mA)
Load Current (mA)
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ACT8309/8310/8311
Rev PrA, 24-Jan-08
TYPICAL PERFORMANCE CHARACTERISTICS
(VIN = VEN = 3.6V, TA = 25C, unless otherwise specified.)
Startup Waveform
ACT8309/8310/8311-007 VIN = 4.2V VOUT = 3.3V IOUT = 1A CH1
Load Transient Response
ACT8309/8310/8311-008 VOUT = 3.3V VIN = 4.2V VOUT = 3.3V CH1
CH2
CH2
CH1: VOUT, 1.0V/div CH2: POK, 2.0V/div TIME: 100s
CH1: VOUT, 100mV/div (AC COUPLED) CH2: Load Current (100mA to 1000mA) TIME: 100s
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PACKAGE OUTLINE
TDFN33-8 PACKAGE OUTLINE AND DIMENSIONS
ACT8309/8310/8311
Rev PrA, 24-Jan-08
SYMBOL
A A1 A3 D E D2 E2 b e L
DIMENSION IN MILLIMETERS MIN
0.700 0.000 0.153 2.900 2.900 2.200 1.400 0.200
DIMENSION IN INCHES MIN
0.028 0.000 0.006 0.114 0.114 0.087 0.055 0.008
MAX
0.800 0.050 0.253 3.100 3.100 2.400 1.600 0.320
MAX
0.031 0.002 0.010 0.122 0.122 0.094 0.063 0.013
0.650 TYP 0.375 0.575
0.026 TYP 0.015 0.023
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 lifesupport 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@activesemi.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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