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Active-Semi
FEATURES
* Multiple Patents Pending * Two Integrated Step-Down DC/DC Converters
- REG1: 350mA - REG2: 550mA
ACT8325
Rev0, 13-May-08
Dual PWM Step-Down DC/DCs in TDFN33 GENERAL DESCRIPTION
The patent-pending ACT8325 integrates two stepdown DC/DCs into a single, thin, space-saving package to provide a cost-effective, highly-efficient ActivePMUTM power management solution. This device is ideal for a wide range of portable handheld equipment that can benefit from the advantages of ActivePMU technology but do not require a high level of integration. REG1 and REG2 are fixed-frequency, current-mode PWM step-down DC/DC converters that are optimized for high efficiency and are capable of supplying up to 350mA and 550mA, respectively. Both outputs are available in a wide range of factorypreset output voltage options, and an adjustable output voltage mode is also available. The ACT8325 is available in a tiny 3mm x 3mm 10-pin Thin-DFN package that is just 0.75mm thin.
* 180 Out-of-Phase Operation
- Reduces Input Capacitor Requirements
* * * *
Fixed or Adjustable Output Voltage Options Independent Enable/Disable Control Minimal External Components 3x3mm, Thin-DFN (TDFN33-10) Package - Only 0.75mm Height - RoHS-Compliant
APPLICATIONS
* Portable Devices and PDAs * MP3/MP4 Players * Wireless Handhelds * GPS Receivers
SYSTEM BLOCK DIAGRAM
REG1
Battery Step-Down DC/DC
OUT1 Adjustable, or 1.2V to 3.3V Up to 350mA
ON1 ON2
System Control
REG2
Step-Down DC/DC
OUT2 Adjustable, or 1.2V to 3.3V Up to 550mA
ACT8325
Active
PMU
TM
Innovative PowerTM
ActivePMUTM is a trademark of Active-Semi.
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www.active-semi.com Copyright (c) 2008 Active-Semi, Inc.
Active-Semi
FUNCTIONAL BLOCK DIAGRAM
ACT8325
Rev0, 13-May-08
Active-Semi
ACT8325
UVLO REG1
VP1 To Battery
SW1 FB1 GP12
ON1 ON2
OUT1
VP2 To Battery
GA
REG2
SW2 FB2 GP12
OUT2
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ActivePMUTM is a trademark of Active-Semi.
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www.active-semi.com Copyright (c) 2008 Active-Semi, Inc.
Active-Semi
ORDERING INFORMATION
PART NUMBER
ACT8325NDAAA-T
ACT8325
Rev0, 13-May-08
VOUT1
Adjustable
VOUT2
Adjustable
PACKAGE
TDFN33-10
PINS
10
TEMPERATURE RANGE
-40C to +85C
OUTPUT VOLTAGE CODES
A Adjustable C 1.2V P 1.3V J 1.4V D 1.5V E 1.8V F 2.5V I 2.8V Q 2.85V G 3.0V H 3.3V
: Output voltage options detailed in this table represent standard voltage options, and are available for samples or production orders. Additional output voltage options, as detailed in the Output Voltage Codes table, are available for production subject to minimum order quantities. Contact Active-Semi for more information regarding semi-custom output voltage combinations. : 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
TOP VIEW
VP1 SW1 GP12 SW2 VP2
1 2 3 4 5
10
FB1 ON2 ON1 GA FB2
Active-Semi
ACT8325
9 8 7 6
Thin - DFN (TDFN 33-10)
Innovative PowerTM
ActivePMUTM is a trademark of Active-Semi.
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www.active-semi.com Copyright (c) 2008 Active-Semi, Inc.
Active-Semi
PIN DESCRIPTIONS
PIN
1 2 3 4 5 6 7 8 9 10 EP
ACT8325
Rev0, 13-May-08
NAME
VP1 SW1 GP12 SW2 VP2 FB2 GA ON1 ON2 FB1 EP
DESCRIPTION
Power Input for REG1. Bypass to GP12 with a high quality ceramic capacitor placed as close as possible to the IC. Switching Node Output for REG1. Connect this pin to the switching end of the inductor. Power Ground for REG1, REG2. Connect GA and GP12 together at single point as close to the IC as possible. Switching Node Output for REG2. Connect this pin to the switching end of the inductor. Power Input for REG2. Bypass to GP12 with a high quality ceramic capacitor placed as close as possible to the IC. Feedback Node for REG2. For fixed output voltage options, connect this pin directly to the output. For the adjustable output voltage options the voltage at this pin is regulated to 0.625V, connect this pin to the center of the output feedback resistor divider for voltage setting. Analog Ground. Connect GA directly to a quiet ground node. Connect GA and GP12 together at a single point as close to the IC as possible. Enable Control Input for REG1. Drive ON1 to VP1 or to a logic high for normal operation, drive to GA or to a logic low to disable REG1. Enable Control Input for REG2. Drive ON2 to VP1or to a logic high for normal operation, drive to GA or to a logic low to disable REG2. Feedback Node for REG1. For fixed output voltage options, connect this pin directly to the output. For the adjustable output voltage options the voltage at this pin is regulated to 0.625V, connect this pin to the center of the output feedback resistor divider for voltage setting. Exposed Pad. Must be soldered to ground on PCB.
Innovative PowerTM
ActivePMUTM is a trademark of Active-Semi.
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www.active-semi.com Copyright (c) 2008 Active-Semi, Inc.
Active-Semi
ABSOLUTE MAXIMUM RATINGS
PARAMETER
VP1, SW1, VP2, SW2 to GP12, FB1, FB2, ON1, ON2 to GA SW1 to VP1, SW2 to VP2 GP12 to GA Junction to Ambient Thermal Resistance (JA) Operating Temperature Range Junction Temperature Storage Temperature Lead Temperature (Soldering, 10 sec)
ACT8325
Rev0, 13-May-08
VALUE
-0.3 to +6 -6 to +0.3 -0.3 to +0.3 33 -40 to 85 125 -55 to 150 300
UNIT
V V V C/W C 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.
Innovative PowerTM
ActivePMUTM is a trademark of Active-Semi.
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www.active-semi.com Copyright (c) 2008 Active-Semi, Inc.
Active-Semi
ELECTRICAL CHARACTERISTICS (REG1)
(VVP1 = 3.6V, TA = 25C, unless otherwise specified.)
ACT8325
STEP-DOWN DC/DC CONVERTER
Rev0, 13-May-08
PARAMETER
VP1 Operating Voltage Range VP1 UVLO Threshold VP1 UVLO Hysteresis Standby Supply Current Shutdown Supply Current Adjustable Output Option Regulation Voltage Output Voltage Regulation Accuracy Line Regulation Load Regulation Current Limit Oscillator Frequency PMOS On-Resistance NMOS On-Resistance SW1 Leakage Current Power Good Threshold Minimum On-Time Logic High Input Voltage Logic Low Input Voltage Thermal Shutdown Temperature Thermal Shutdown Hysteresis ON1 ON1
TEST CONDITIONS
Input Voltage Rising Input Voltage Falling
MIN
3.1 2.9
TYP
3 80 130
MAX
5.5 3.1
UNIT
V V mV
200 1
A A V
ON1 = GA, VVP1 = 4.2V
0.1 0.625
VNOM1 < 1.3V, IOUT1 = 10mA VNOM1 1.3V, IOUT1 = 10mA VVP1 = Max(VNOM1 + 1V, 3.2V) to 5.5V IOUT1 = 10mA to 350mA
-2.4% -1.2%
VNOM1 VNOM1 0.15 0.0017
+1.8% +1.8%
V %/V %/mA A
0.45 VOUT1 20% of VNOM1 VOUT1 = 0V ISW1 = -100mA ISW1 = 100mA VVP1 = 5.5V, VSW1 = 5.5V or 0V 1.35
0.6 1.6 530 0.52 0.27 0.88 0.46 1 94 70 1.85
MHz kHz A %VNOM1 ns V
1.4 0.4 160 20
V C C
Temperature Rising Temperature Falling
: VNOM1 refers to the nominal output voltage level for VOUT1 as defined by the Ordering Information section.
Innovative PowerTM
ActivePMUTM is a trademark of Active-Semi.
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www.active-semi.com Copyright (c) 2008 Active-Semi, Inc.
Active-Semi
ACT8325
STEP-DOWN DC/DC CONVERTER
Rev0, 13-May-08
ELECTRICAL CHARACTERISTICS (REG2)
(VVP2 = 3.6V, TA = 25C, unless otherwise specified.)
PARAMETER
VP2 Operating Voltage Range VP2 UVLO Threshold VP2 UVLO Hysteresis Standby Supply Current Shutdown Supply Current Adjustable Output Option Regulation Voltage Output Voltage Regulation Accuracy Line Regulation Load Regulation Current Limit Oscillator Frequency PMOS On-Resistance NMOS On-Resistance SW2 Leakage Current Power Good Threshold Minimum On-Time Logic High Input Voltage Logic Low Input Voltage Thermal Shutdown Temperature Thermal Shutdown Hysteresis ON2 ON2
TEST CONDITIONS
Input Voltage Rising Input Voltage Falling
MIN
3.1 2.9
TYP
3 80 130
MAX
5.5 3.1
UNIT
V V mV
200 1
A A V
ON2 = GA, VVP2 = 4.2V
0.1 0.625
VNOM2 < 1.3V, IOUT2 = 10mA VNOM2 1.3V, IOUT2 = 10mA VVP2 = Max(VNOM2 + 1V, 3.2V) to 5.5V IOUT2 = 10mA to 550mA
-2.4% -1.2%
VNOM2 VNOM2 0.15 0.0017
+1.8% +1.8%
V %/V %/mA A
0.65 VOUT2 20% of VNOM2 VOUT2 = 0V ISW2 = -100mA ISW2 = 100mA VVP2 = 5.5V, VSW2 = 5.5V or 0V 1.35
0.85 1.6 530 0.40 0.27 0.68 0.46 1 94 70 1.85
MHz kHz A %VNOM2 ns V
1.4 0.4 160 20
V C C
Temperature Rising Temperature Falling
: VNOM2 refers to the nominal output voltage level for VOUT2 as defined by the Ordering Information section.
Innovative PowerTM
ActivePMUTM is a trademark of Active-Semi.
-7-
www.active-semi.com Copyright (c) 2008 Active-Semi, Inc.
Active-Semi
ACT8325
STEP-DOWN DC/DC CONVERTER
Rev0, 13-May-08
TYPICAL PERFORMANCE CHARACTERISTICS
(ACT8325NDAAA, VVP1 = VVP2 = 3.6V, L = 3.3H, CVP1 = CVP2 = 2.2F, COUT1 = COUT2 = 10F, TA = 25C, unless otherwise specified.)
REG1 Efficiency vs. Load Current
95 90 85 VOUT1 = 1.2V VIN = 3.6V 100 ACT8325-001
REG2 Efficiency vs. Load Current
ACT8325-002 VOUT2 = 3.3V 3.6V
90
Efficiency (%)
80 75 70 65 60 55 50 1 10
VIN = 4.2V
Efficiency (%)
4.2V 80
70
60
50 100 1000 0.1 1 10 100 1000
Output Current (mA)
Output Current (mA)
OUT1 Regulation Voltage
0.67 0.56 0.44 IOUT1 = 35mA 0.55 0.45 ACT8325-003
OUT2 Regulation Voltage
ACT8325-004 IOUT2 = 35mA
OUT1 Voltage (%)
0.33 0.22 0.11 0.00 -0.11 -0.22 -0.33 -0.44 -0.56 -0.67 -40 -20 0 20 40 60
OUT2 Voltage (%)
0.36 0.27 0.18 0.09 0.00 -0.09 -0.18 -0.27 -0.36 -0.45 -0.55
85
-40
-20
0
20
40
60
85
Temperature (C)
Temperature (C)
REG1 MOSFET Resistance
600 500 PMOS 440 360 280 ACT8325-005
REG2 MOSFET Resistance
ACT8325-006
PMOS
RDSON (m)
400 300 200 100 NMOS
RDSON (m)
NMOS 200 120 40
0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VP1 Voltage (V)
VP2 Voltage (V)
Innovative PowerTM
ActivePMUTM is a trademark of Active-Semi.
-8-
www.active-semi.com Copyright (c) 2008 Active-Semi, Inc.
Active-Semi
ACT8325
STEP-DOWN DC/DC CONVERTER
Rev0, 13-May-08
FUNCTIONAL DESCRIPTION
General Description
REG1 and REG2 are fixed-frequency, currentmode, synchronous PWM step-down converters that achieve peak efficiencies of up to 97%. REG1 is capable of supplying up to 350mA of output current, while REG2 supports up to 550mA. These regulators operate with a fixed frequency of 1.6MHz, minimizing noise in sensitive applications and allowing the use of small external components. REG1 and REG2 are available with a variety of standard and custom output voltages, as described in the Ordering Information section of this datasheet.
Compensation
REG1 and REG2 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.
Thermal Shutdown
The ACT8325 integrates thermal shutdown protection circuitry to prevent damage resulting from excessive thermal stress, as may be encountered under fault conditions. This circuitry disables all regulators if the ACT8325 die temperature exceeds 160C, and prevents the regulators from being enabled until the IC temperature drops by 20C (typ).
100% Duty Cycle Operation
Both REG1 and REG2 are capable of operating at up to 100% duty cycle. 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.
Input Capacitor Selection
The input capacitor reduces peak currents and noise induced upon the voltage source. A 2.2F ceramic capacitor for each of REG1 and REG2 is recommended for most applications.
Synchronous Rectification
REG1 and REG2 both feature integrated n-channel synchronous rectifiers, maximizing efficiency and minimizing the total solution size and cost by eliminating the need for external rectifiers.
Output Capacitor Selection
For most applications, 10F ceramic output capacitors are recommended for both REG1 and REG2. 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.
Enabling and Disabling REG1 and REG2
Each of the ACT8325's regulators features independent pin-controlled enable control. Drive ON1 to a logic-high to enable REG1, drive ON1 to a logiclow to disable REG1. Similarly, drive ON2 to a logic-high to enable REG2, drive ON2 to a logic-low to disable REG2. When disabled, each regulator's supply current drops to less than 1A.
Output Voltage Programming
Figure 4: Output Voltage Programming
OUTx ACT8325 FBx RFB2 CFF RFB1
Soft-Start
REG1 and REG2 each include matched soft-start circuitry. When enabled, the output voltages track the internal 80s soft-start ramp and both power up in a monotonic manner that is independent of loading on either output. This circuitry ensures that both outputs power up in a controlled manner, greatly simplifying power sequencing design considerations.
Figure 4 shows the feedback network necessary to set the output voltage when using the adjustable
Innovative PowerTM
ActivePMUTM is a trademark of Active-Semi.
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www.active-semi.com Copyright (c) 2008 Active-Semi, Inc.
Active-Semi
ACT8325
STEP-DOWN DC/DC CONVERTER
PCB Layout Considerations
Rev0, 13-May-08
output voltage option. output voltage option. Select components as follows: Set RFB2 = 51k, then calculate RFB1 using the following equation:
V RFB1 = RFB2 OUTX - 1 V FBX
(1)
where VFBX is 0.625V. Finally choose CFF using the following equation:
C FF =
2.2 x 10 -6 R FB1
(2)
Where RFB1 = 47k, use 47pF.
Inductor Selection
REG1 and REG2 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. These devices were optimized for operation with 3.3H inductors, although inductors in the 2.2H to 4.7H range can be used. Choose an inductor 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%.
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. Stepdown 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, connect the output node directly to the FBx pin. For adjustable output voltage options, connect the feedback resistors and feed-forward capacitor to the FBx pin through the shortest possible route. In both cases, the feedback path should be routed to maintain sufficient distance from switching nodes to prevent noise injection.
Innovative PowerTM
ActivePMUTM is a trademark of Active-Semi.
- 10 -
www.active-semi.com Copyright (c) 2008 Active-Semi, Inc.
Active-Semi
ACT8325
PACKAGE INFORMATION
Rev0, 13-May-08
PACKAGE OUTLINE
TDFN33-10 PACKAGE OUTLINE AND DIMENSIONS
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 2.350 1.650 0.200
DIMENSION IN INCHES MIN
0.028 0.0000 0.006 0.114 0.114 0.093 0.065 0.008
MAX
0.800 0.050 0.253 3.100 3.100 2.450 1.750 0.320
MAX
0.031 0.002 0.010 0.122 0.122 0.096 0.069 0.012
0.500 TYP 0.300 0.500
0.020 TYP 0.012 0.020
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
Innovative PowerTM
ActivePMUTM is a trademark of Active-Semi.
- 11 -
www.active-semi.com Copyright (c) 2008 Active-Semi, Inc.

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