Page 1
A
f
Description
The PAM2303 is a 3A step-down DC-DC converter. It operates in two
different modes: PSM and PWM modes. At light load, it
automactically enters into the PSM mode to improve efficiency. At
heavy load, the constant frequency PWM control performs excellent
stability and transient response. No external compensation
components are required.
The PAM2303 supports a range of input voltages from 2.7V to 5.5V.
The output voltage is adjustable from 0.6V to the input voltage. The
PAM2303 employs 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 1µA. Other key features include over-
temperature and short circuit protection, and under-voltage lockout to
prevent deep battery discharge.
The PAM2303 delivers 3A maximum output current while consuming
only 42µA of no-load quiescent current. Ultra-Low R
MOSFETs and 100% duty cycle operation make the PAM2303 an
ideal choice for high-output voltage, high-current applications which
require a low dropout threshold.
The PAM2303 is available in SOP-8(EP), DFN3X3-10 and QFN3X3-
16 package.
DS(ON)
integrated
Product Line o
Diodes Incorporated
PAM2303
3A LOW NOISE STEP-DOWN DC-DC CONVERTER
Pin Assignments
Features
• Output Current: Up to 3A
• Output Voltage: 0.6V to V
• Input Voltage: 2.7 to 5.5V
• Efficiency up to 95%
• 42µA (typ) No Load Quiescent Current
• Shutdown Current: <1A
• 100% Duty Cycle Operation
• 1.5MHz Switching Frequency
• Analog Soft Start
• No external Compensation Required
• Current Limit Protection
• Thermal Shutdown
• SOP-8(EP), DFN3X3-10 and QFN3X3-16 Package
PAM2303
Document number: DSxxxxx Rev. 1 - 2
IN
Applications
• 5V or 3.3V Point of Load Conversion
• Telecom/Networking Equipment
• Set Top Boxes
• Storage Equipment
• Video Cards
• DDR Power Supply
1 of 14
www.diodes.com
November 2012
© Diodes Incorporated
Page 2
A
f
Typical Applications Circuit
Product Line o
Diodes Incorporated
PAM2303
1R
⎛
⎞
+×=
16.0
V
O
⎜
⎝
⎟
2R
⎠
Pin Descriptions
Pin
Name
PGND 1, 2, 3 2 — Main power ground pin.
FB 4 3 6 Feedback voltage to internal error amplifier, the threshold voltage is 0.6V.
GND 5 4 4 Signal ground for small signal components.
NC 6, 16 — 7 Not connected.
EN 7 5 5
Test 8 6 — Test mode. “Low”connection is recommended.
VIN 9 7 8, 9, 10 Bias supply. Chip main power supply pin.
PVIN 10, 11, 12 8 — Input supply for power stage. Must be closely decoupled to PGND.
SW 13, 14, 15 1 1, 2, 3 The drains of the internalmain and synchronous power MOSFET.
QFN3x3-16 SOP-8EP DFN3x3-10
Package Name
Function
Enable control input. Force this pin voltage above 1.5V, enables the chip, and below
0.3V shuts down the device.
Functional Block Diagram
PAM2303
Document number: DSxxxxx Rev. 1 - 2
2 of 14
www.diodes.com
November 2012
© Diodes Incorporated
Page 3
A
f
Product Line o
Diodes Incorporated
PAM2303
Absolute Maximum Ratings (@T
These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability.
All voltages are with respect to ground.
Parameter Rating Unit
Input Voltage PVIN, VIN
SW Pin Voltage
FB Pin Voltage
EN Pin Voltage -0.3 to +6.0 V
Maximum Junction Temperature 150 °C
Storage Temperature Range -65 to +150 °C
Soldering Temperature 300, 5sec °C
Recommended Operating Conditions (@T
Parameter Rating Unit
Supply Voltage 2.7 to 5.5 V
Junction Temperature Range -40 to +125
Ambient Temperature Range -40 to +85
= +25°C, unless otherwise specified.)
A
6 V
-0.3 to (PV
-0.3 to (V
+0.3)
IN
+0.3)
IN
= +25°C, unless otherwise specified.)
A
V
V
°C
Thermal Information
Parameter Symbol Package Max Unit
SOP-8EP 90
Thermal Resistance (Junction to Ambient)
Thermal Resistance (Junction to Case)
PAM2303
Document number: DSxxxxx Rev. 1 - 2
θ
JA
θ
JC
www.diodes.com
DFN3x3-10 60
QFN3x3-16 35
SOP-8EP 11
DFN3x3-10 8.5
QFN3x3-16 11
3 of 14
°C/W
November 2012
© Diodes Incorporated
Page 4
A
f
Product Line o
Diodes Incorporated
PAM2303
Electrical Characteristics (@T
Parameter Symbol Test Conditions Min Typ Max Units
Input Voltage Range
Output Voltage Range
UVLO Threshold
Regulated Output Voltage Accuracy
Regulated Feedback Voltage
FB Leakage Current
Output Voltage Line Regulation LNR
Output Voltage Load Regulation LDR
Quiescent Current
Shutdown Current
Current Limit
Oscillator Frequency
Drain-Source On-State Resistance
High Efficiency η 95 %
PSM Threshold
Analog Soft Start Time
EN Threshold High
EN Threshold Low
EN Leakage Current
Over Temperature Protection OTP 150 °C
OTP Hysteresis OTH 30 °C
= +25°C, VIN = 3.6V, VO = 1.8V, CIN = 33µF, CO = 22µF, L = 2.2µH unless otherwise specified.)
A
IN
O
Rising
V
IN
Hysteresis 240 mV
V
V
V
UVLO
VIN Falling
V
IO = 0 to 3A
O
V
I
f
R
DS(ON)
V
V
I
FB
I
I
SD
LIM
OSC
I
TH
t
I
EN
0.591 0.600 0.609 V
FB
VO = 1V
V
= 2.5V to 5V
IN
I
= 0A to 3A
O
No load 42 90 µA
Q
VEN = 0V
4 A
1.2 1.5 1.8 MHz
VIN = 3.3V, VO = 1.2V, L = 1µH
From enable to output regulation 0.5 ms
S
1.5 V
EH
0.3 V
EL
VIN = VEN = 0V
High Side 85
Low Side 60
2.7 5.5 V
0.6
VIN
2.4 2.5 V
1.8 V
-3 +3 %
-50 +50 nA
0.2 %/V
0.5 %/A
1 µA
450 mA
-1.0 +1.0 µA
V
mΩ
PAM2303
Document number: DSxxxxx Rev. 1 - 2
4 of 14
www.diodes.com
November 2012
© Diodes Incorporated
Page 5
A
f
Typical Performance Characteristics (@T
Product Line o
Diodes Incorporated
PAM2303
= +25°C, CIN = 10µF, CO = 10µF, L = 4.7µH unless otherwise specified.)
A
PAM2303
Document number: DSxxxxx Rev. 1 - 2
5 of 14
www.diodes.com
November 2012
© Diodes Incorporated
Page 6
A
f
Typical Performance Characteristics (cont.) (@T
Product Line o
Diodes Incorporated
PAM2303
= +25°C, CIN = 10µF, CO = 10µF, L = 4.7µH unless otherwise specified.)
A
PAM2303
Document number: DSxxxxx Rev. 1 - 2
6 of 14
www.diodes.com
November 2012
© Diodes Incorporated
Page 7
A
f
Typical Performance Characteristics (cont.) @T
Product Line o
Diodes Incorporated
PAM2303
= +25°C, CIN = 10µF, CO = 10µF, L = 4.7µH unless otherwise specified.)
A
PAM2303
Document number: DSxxxxx Rev. 1 - 2
www.diodes.com
7 of 14
November 2012
© Diodes Incorporated
Page 8
A
f
(
Product Line o
Diodes Incorporated
PAM2303
Application Information
The basic PAM2303 application circuit is shown in Page 1. External component selection is determined by the load requirement, selecting L first
and then C
Inductor Selection
For most applications, the value of the inductor will fall in the range of 1μH to 3.3μH. Its value is chosen based on the desired ripple current and
efficiency. Large value inductors lower ripple current and small value inductors result in higher ripple currents. Higher V
the ripple current as shown in equation 3A reasonable starting point for setting ripple current is ΔI
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 4.2A rated inductor should be enough for most applications (3A + 1.2A). For better efficiency, choose a low DC-resistance inductor.
V
L 1µH 1.5µH 2.2µH 2.2µH 3.3µH
CIN and C
In continuous mode, the source current of the top MOSFET is a square wave of duty cycle V
ESR input capacitor sized for the maximum RMS current must be used. The maximum RMS capacitor current is given by:
This formula has a maximum at V
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 C
Typically, once the ESR requirement for C
output ripple ΔV
ΔV
Where f = operating frequency, C = output capacitance and ΔI
highest at maximum input voltage since ΔI
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 PAM2303. 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:
I
is the step-down converter quiescent current. The term tsw is used to estimate the full load step-down converter switching losses.
Q
PAM2303
Document number: DSxxxxx Rev. 1 - 2
and C
IN
Δ
I
1.2V 1.5V 1.8V 2.5V 3.3V
O
OUT
C
IN
OUT
.
OUT
1
()()
Lf
⎛
⎜
−=
1
V
OUTL
⎜
⎝
⎞
V
OUT
⎟
Equation 1
⎟
V
IN
⎠
Selection
[]
required
OUT
is determined by:
OUT
≈ ΔIL(ESR = 1/8fC
2
=
IP
OD
≅
II
OMAXRMS
= 2V
IN
is driven by the required effective series resistance (ESR).
OUT
V
()
, where I
OUT
has been met, the RMS current rating generally far exceeds the I
OUT
)
increases with input voltage.
L
−+
)
RVVRV
DSONLOINDSONHO
IN
or V
IN
= 1.2A (40% of 3A).
L
. To prevent large voltage transients, allow
OUT/VIN
−
VVV
V
IN
RMS
2/1
OUTINOUT
= I
/2. This simple worst-case condition is commonly used for design because even
OUT
= ripple current in the inductor. For a fixed output voltage, the output ripple is
L
()
t
SW
++
8 of 14
www.diodes.com
VIIF
INQOS
(P-P) requirement. The
RIPPLE
also increases
OUT
November 2012
© Diodes Incorporated
Page 9
A
f
Product Line o
Diodes Incorporated
PAM2303
Application Information (cont.)
Thermal Consideration (cont.)
For the condition where the step-down converter is in dropout at 100% duty cycle, the total device dissipation reduces to:
P
Since R
DS(ON)
voltage range. The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surrounding airflow
and temperature difference between junction and ambient. The maximum power dissipation can be calculated by the following formula:
Where TJ(max) is the maximum allowable junction temperature +125°C. T
the junction to the ambient. Based on the standard JEDEC for a two layers thermal test board, the thermal resistance θ
and SOP-8(EP) 90°C/W, respectively. The maximum power dissipation at T
P = (125°C - 25°C)/68°C/W = 1.47W(QFN3X3-16)
P = (125°C - 25°C)/90°C/W = 1.11W(SOP-8)
Setting the Output Voltage
The internal reference is 0.6V (Typical). The output voltage is calculated as below:
The output voltage is given by Table 1.
Table 1: Resistor recommended for output voltage setting
V
1.2V 150k 150k
1.5V 225k 150k
1.8V 300k 150k
2.5V 475k 150k
3.3V 680k 150k
Pulse Skipping Mode (PSM) Description
When load current decreases, the peak switch current in Power-PMOS will be lower than skip current threshold and the device will enter into
Pulse Skipping Mode.
In this mode, the device has two states, working state and idle state. First, the device enters into working state cont rolled by internal error
amplifier.When the feedback voltage gets higher than internal reference voltage, the device will enter into low I idle state with most of internal
blocks disabled. The output voltage will be reduced by loading or leakage current. When the feedback voltage gets lower than the internal
reference voltage, the convertor will start a working state again.
100% Duty Cycle Operation
As the input voltage approaches the output voltage, the converter turns the P-Channel transistor continuously on. In this mode the output voltage
is equal to the input voltage minus the voltage drop across the P-Channel transistor:
V
where R
DSON
UVLO and Soft-Start
The reference and the circuit remain reset until the VIN crosses its UVLO threshold.
The PAM2303 has an internal soft-start circuit that limits the in-rush current during start-up. This prevents possible voltage drops of the input
voltage and eliminates the output voltage overshoot. The soft-start make the output voltage rise up smoothly.
2
= I
R
D
O
, quiescent current, and switching losses all vary with input voltage, the total losses should be investigated over the complete input
=
P
D
V
O
O
= VIN – I
OUT
= P-Channel switch ON resistance, I
DSON H
θ
JA
⎛
16.0
⎜
⎝
LOAD
+IQVIN
−
TT
A)MAX(J
1R
⎞
+×=
⎟
2R
⎠
R1 R2
(R
+ RL)
DSON
= Output current, RL = Inductor DC resistance
LOAD
is the ambient temperature and θJA is the thermal resistance from
A
of QFN3X3-16 68°C/W
JA
= +25°C can be calculated by the following formula:
A
PAM2303
Document number: DSxxxxx Rev. 1 - 2
9 of 14
www.diodes.com
November 2012
© Diodes Incorporated
Page 10
A
f
Product Line o
Diodes Incorporated
PAM2303
Application Information (cont.)
Short Circuit Protection
The switch peak current is limited cycle-by-cycle to a typical value of 4A. In the event of an output voltage short circuit, the device operates with
a frequency of 500kHz and minimum duty cycle, therefore the average input current is more smaller than current limit.
Thermal Shutdown
When the die temperature exceeds +150°C, a reset occurs and the reset remains until the temperature decrease to +120°C, at which time the
circuit can be restarted.
Ordering Information
Part Number Output Voltage Package Packaging
PAM2303AJEADJR ADJ QFN3x3-16 3000 Units/Tape & Reel
PAM2303BECADJR
PAM2303CFGADJR
ADJ
ADJ
SOP-8EP 2500 Units/Tape & Reel
DFN3x3-10 3000 Units/Tape & Reel
Marking Information
PAM2303
Document number: DSxxxxx Rev. 1 - 2
10 of 14
www.diodes.com
November 2012
© Diodes Incorporated
Page 11
A
f
Package Outline Dimensions (All dimensions in mm.)
SOP-8EP
Product Line o
Diodes Incorporated
PAM2303
PAM2303
Document number: DSxxxxx Rev. 1 - 2
11 of 14
www.diodes.com
November 2012
© Diodes Incorporated
Page 12
A
f
Package Outline Dimensions (cont.) (All dimensions in mm.)
DFN3x3-10
Product Line o
Diodes Incorporated
PAM2303
PAM2303
Document number: DSxxxxx Rev. 1 - 2
12 of 14
www.diodes.com
November 2012
© Diodes Incorporated
Page 13
A
f
Package Outline Dimensions (cont.) (All dimensions in mm.)
QFN3x3-16
Product Line o
Diodes Incorporated
PAM2303
Notes: 1. Controlling dimensions are millimeters (angles in degrees).
2. Coplanarity applies to the exposed pads as well as the terminals.
3. DAP is 1.90 x 1.90mm.
PAM2303
Document number: DSxxxxx Rev. 1 - 2
13 of 14
www.diodes.com
November 2012
© Diodes Incorporated
Page 14
A
f
Product Line o
Diodes Incorporated
PAM2303
DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
(AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION).
Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes
without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the
application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or
trademark rights, nor the rights of others. Any Customer or user of this document or products described herein in such applications shall assume
all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on Diodes Incorporated
website, harmless against all damages.
Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized sales channel.
Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall indemnify and
hold Diodes Incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees arising out of, directly or
indirectly, any claim of personal injury or death associated with such unintended or unauthorized application.
Products described herein may be covered by one or more United States, international or foreign patents pending. Product names and markings
noted herein may also be covered by one or more United States, international or foreign trademarks.
This document is written in English but may be translated into multiple languages for reference. Only the English version of this document is the
final and determinative format released by Diodes Incorporated.
Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express
written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:
A. Life support devices or systems are devices or systems which:
1. are intended to implant into the body, or
2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the
labeling can be reasonably expected to result in significant injury to the user.
B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the
failure of the life support device or to affect its safety or effectiveness.
Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any
use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related
information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its
representatives against any damages arising out of the use of Diodes Incorporated products in such safety-critical, life support devices or systems.
Copyright © 2012, Diodes Incorporated
www.diodes.com
IMPORTANT NOTICE
LIFE SUPPORT
PAM2303
Document number: DSxxxxx Rev. 1 - 2
14 of 14
www.diodes.com
November 2012
© Diodes Incorporated
Loading...