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부품번호 | PAM2306D 기능 |
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기능 | DUAL HIGH-EFFICIENCY PWM STEP-DOWN DC-DC CONVERTER | ||
제조업체 | Diodes | ||
로고 | |||
전체 12 페이지수
A Product Line of
Diodes Incorporated
PAM2306D
DUAL HIGH-EFFICIENCY PWM STEP-DOWN DC-DC CONVERTER
Description
The PAM2306D is a dual step-down current mode, DC-DC converter.
At heavy load, the constant-frequency PWM control performs
excellent stability and transient response. To ensure the longest
battery life in portable applications, the PAM2306D provides a
powersaving Pulse-Skipping Modulation (PSM) mode to reduce
quiescent cur rent under light load operation.
The PAM2306D supports a range of input voltages from 2.5V to 5.5V,
allowing the use of a single Li+/Li-polymer cell, multiple Alkaline/NiMH
cell, USB, and other standard power sources. The dual output
voltages are available for adjustment. All versions employ internal
power switch and synchronous rectifier to minimize external part
count and realize high efficiency. During shutdown, the input is
disconnected from the output and the shutdown current is less than
0.1µA. Other key features include under-voltage lockout to prevent
deep battery discharge.
Pin Assignments
Features
Efficiency up to 96%
Only 40μA (Typ per Channel) Quiescent Current
Output Current: Up to 1A per Channel
Internal Synchronous Rectifier
1.5MHz Switching Frequency
Soft-Start
Under-Voltage Lockout
Short Circuit Protection
Thermal Shutdown
Small 12L WDFN3x3 Package
Pb-Free and RoHS Compliant
Typical Applications Circuit
Applications
Cellular Phone
Portable Electronics
Personal Information Appliances
Wireless and DSL Modems
MP3 Players
PAM2306D
Document number: DS36394 Rev. 2 - 2
VOUT
VREF1
Rx1
Rx2
1 of 12
www.diodes.com
December 2014
© Diodes Incorporated
A Product Line of
Diodes Incorporated
PAM2306D
Typical Performance Characteristics (@TA = +25°C, CIN = 10µF, CO = 10µF, L = 4.7µH, unless otherwise specified.)
PAM2306D
Document number: DS36394 Rev. 2 - 2
4 of 12
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December 2014
© Diodes Incorporated
4페이지 A Product Line of
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PAM2306D
Application Information
The basic PAM2306D application circuit is shown in Page 1. External component selection is determined by the load requirement, selecting L
first and then CIN and COUT.
Inductor Selection
For most applications, the value of the inductor will fall in the range of 1μH to 4.7μH. Its value is chosen based on the desired ripple current.
Large value inductors lower ripple current and small value inductors result in higher ripple currents. Higher VIN or VOUT also increases the
ripple current as shown in Equation 1. A reasonable starting point for setting ripple current is ∆IL = 400mA (40% of 1A).
IL
f
1
L
VOUT
1
VOUT
VIN
Equation (1)
The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core
saturation. Thus, a 1.4A rated inductor should be enough for most applications (1A + 400mA). For better efficiency, choose a low DC-
resistance inductor.
VO
1.2V
1.5V
1.8V
2.5V
3.3V
L 2.2 µH 2.2 µH 2.2 µH 4.7 µH 4.7µH
CIN and COUT Selection
In continuous mode, the source current of the top MOSFET is a square wave of duty cycle VOUT/VIN. To prevent large voltage transients, a low
ESR input capacitor sized for the maximum RMS current must be used. The maximum RMS capacitor current is given by:
CINrequiredIRMS IOMAX
VOUT
VIN VOUT
VIN
1/ 2
This formula has a maximum at VIN =2VOUT, where IRMS = IOUT/2. This simple worst-case condition is commonly used for design because
even significant deviations do not offer much relief. Note that the capacitor manufacturer's ripple current ratings are often based on 2000 hours
of life. This makes it advisable to further derate the capacitor, or choose a capacitor rated at a higher temperature than required. Consult the
manufacturer if there is any question.
The selection of COUT is driven by the required effective series resistance (ESR).
Typically, once the ESR requirement for COUT has been met, the RMS current rating generally far exceeds the IRIPPLE (P-P) requirement. The
output ripple ∆VOUT is determined by:
VOUT
IL ESR
1
8fCOUT
Where f = operating frequency, COUT = output capacitance and ∆IL = ripple current in the inductor. For a fixed output voltage, the output ripple
is highest at maximum input voltage since ∆IL increases with input voltage.
Using Ceramic Input and Output Capacitors
Higher values, lower cost ceramic capacitors are now becoming available in smaller case sizes. Their high ripple current, high voltage rating
and low ESR make them ideal for switching regulator applications. Using ceramic capacitors can achieve very low output ripple and small
circuit size.
When choosing the input and output ceramic capacitors, choose the X5R or X7R dielectric formulations. These dielectrics have the best
temperature and voltage characteristics of all the ceramics for a given value and size.
Thermal Consideration
Thermal protection limits power dissipation in the PAM2306D. When the junction temperature exceeds 150°C, the OTP (Over Temperature
Protection) starts the thermal shutdown and turns the pass transistor off. The pass transistor resumes operation after the junction temperature
drops below 120°C.
For continuous operation, the junction temperature should be maintained below 125°C. The power dissipation is defined as:
PD IO2
VORDS(ON)H
VIN VO
VIN
RDS(ON)L
tSW FSIO IQ
VIN
IQ is the step-down converter quiescent current. The term tsw is used to estimate the full load step-down converter switching losses.
PAM2306D
7 of 12
December 2014
Document number: DS36394 Rev. 2 - 2
www.diodes.com
© Diodes Incorporated
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부품번호 | 상세설명 및 기능 | 제조사 |
PAM2306 | Dual High-Efficiency PWM Step-Down DC-DC Coverter | Power Analog Micoelectronics |
PAM2306 | DUAL HIGH-EFFICIENCY PWM STEP-DOWN DC-DC CONVERTER | Diodes |
DataSheet.kr | 2020 | 연락처 | 링크모음 | 검색 | 사이트맵 |