PAM PAM2303

PAM2303
3A Low Noise Step-Down DC-DC Converter
Features
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Description
T h e PA M 2 3 0 3 i s a 3 A s t e p - d o w n D C - D C
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 constantfrequency P WM control per for ms exc ellent
stability and transient response. No external
compensation components are required.
Output Current: Up to 3A
Output Voltage: 0.6V to V IN
Input Voltage: 2.7 to 5.5V
Efficiency up to 95%
42 μA (Typ) No Load Quiescent Current
Shutdown Current: <1 μA
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
The PAM2303 supports a range of input voltages
fr om 2.7 V to 5.5 V. The ou tput v olta ge is
adjustable from 0.6V to the input voltage. The
PAM2303 employs internal power switch and
synchronous rectifier to minimize external part
c o u n t a n d r e a l i z e h i g h e ff i c i e n c y. D u r i n g
shutdown, the input is disconnected from the
output and the shutdown current is less than 1 μA.
Other key features include over-temperature and
sh or t c ir c uit p r otec ti on , and u nde r -v ol tag e
lockout to prevent deep battery discharge.
Applications
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5V or 3.3V Point of Load Conversion
Telecom/Networking Equipment
Set Top Boxes
Storage Equipment
Video Cards
DDR Power Supply
The PAM2303 delivers 3A maximum output
current while consuming only 42μA of no-load
quiescent current. Ultra-low RDS(ON) integrated
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.
T h e PA M 2 3 0 3 i s a v a i l a b l e i n S O P - 8 ( E P ) ,
DFN3X3-10, and QFN3X3-16 package.
Typical Application
U1
L1
VIN
PVIN
SW
R3
1k
C1
40uF
22uF
1
VOUT
C3
R1 100pF
PAM2307
VIN PAM2303
EN
2
C2
FB
30uF
22uF
C4
1uF
TEST
R2
 R1 
VO = 0.6 
1+

 R2 
Power Analog Microelectronics, Inc
www.poweranalog.com
11/2011 Rev1.2
1
PAM2303
3A Low Noise Step-Down DC-DC Converter
Block Diagram
VIN
1.5M
OSC
SLOPE
COMP
FREQ
SHIFT
OSC
+
IAMP
-
PVIN
FB
MAIN
SWITCH (PCH )
S Q
R1
R Q
RS LATCH
EA
R2
+
VIN
SWITCHING
LOGIC
AND
BLANKING
CIRCUIT
ANTISHOOT THRU
SW
COMP
0.6VREF
EN
+
IRCMP
-
SHUTDOWN
GND
SYNCHRONOUS
RECTIFIER (NCH )
PGND
TEST
Pin Configuration & Marking Information
Top View
Top View
SOP-8(EP)
QFN 3X3-16
8
16 15 14 13
PGND
PGND
PGND
FB
1
P2303A
XXXYW
2
3
12
PVIN
11
PVIN
PVIN
VIN
10
4
9
5
6
7
7
6
5
A/B: Pin Configuration
Y: Year
W: Week
X: Internal Code
P2303B
XXXYW
8
1
2
3
4
Pin Description
Name
QFN3X3-16
SOP-8(EP)
Function
PGND
1,2,3
2
Main power ground pin
FB
4
3
Feedback voltage to internal error amplifier, the threshold voltage is 0.6V.
GND
5
4
Signal ground for small signal components.
NC
6,16
-
No connected
EN
7
5
Test
8
6
Test mode. “
Low”connection is recommended.
VIN
9
7
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
The drains of the internal main and synchronous power MOSFET.
Enable control input. Force this pin voltage above 1.5V, enables the chip,
and below 0.3V shuts down the device.
Power Analog Microelectronics, Inc
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11/2011 Rev1.2
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PAM2303
3A Low Noise Step-Down DC-DC Converter
Pin Configuration & Marking Information
Top View
DFN3X3-10
SW
1
SW
2
P2303C
XXXYW
10
VIN
9
VIN
8
VIN
SW
3
GND
4
7
NC
EN
5
6
FB
C:
Y:
W:
X:
Pin Configuration
Year
Week
Internal Code
GND
(Exposed Pad)
Pin Description
Name
DFN3X3-10
Function
SW
1,2,3
GND
4
EN
5
FB
6
Feedback voltage to internal error amplifier, the threshold voltage is 0.6V.
NC
7
No connec ted
VIN
8,9,10
The drains of the internal main and synchronous power MOSFET.
GND
Enable control input. Force this pin voltage above 1.5V, enables the chip, and
below 0.3V shuts down the device.
Bias supply. Chip main power supply pin
Absolute Maximum Ratings
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.
Input Voltage PV IN,V IN......................................6V
SW Pin Voltage......................-0.3V to (PV IN+0.3V)
FB Pin Voltage.........................-0.3V to (V IN+0.3V)
EN Pin Voltage...................................- 0.3V to -6V
Maximum Junction Temperature..................150°C
Storage Temperature Range...........-65°C to 150°C
Soldering Temperature.......................300°C, 5sec
Recommended Operating Conditions
Supply Voltage..................................2.7V to 5.5V
Junction Temperature Range..........-40 °C to 125 °C
Ambient Temperature Range...........-40 °C to 85 °C
Thermal Information
Parameter
Thermal Resistanc e (Junction to Ambient)
Thermal Resistance (Junction to Case)
Symbol
θJA
θJC
Package
Maximum
SOP-8(EP)
90
DFN3X3-10
60
QFN3X3-16
35
SOP-8(EP)
11
DFN3X3-10
8.5
QFN3X3-16
11
Unit
°C/W
°C/W
Power Analog Microelectronics, Inc
www.poweranalog.com
11/2011 Rev1.2
3
PAM2303
3A Low Noise Step-Down DC-DC Converter
Electrical Characteristic
TA =25 °C , Vin=3.6V, Vo=1.8V, Cin=33uF,Co=22uF, L=2.2uH, unless otherwise noted.
PARAMETER
SYMBOL
Test Conditions
MIN
TYP
MAX
UNITS
Input Voltage Range
VIN
2.7
5.5
V
Output Voltage Range
VO
0.6
V IN
V
2.5
V
UVLO Threshold
VUV LO
V IN Rising
2.4
Hys teresis
240
V IN Falling
Regulated Output Voltage Accuary
VO
Regulated Feedback Voltage
VF B
FB Leak age Current
IF B
mV
1.8
IO = 0 to 3A
V
-3
0.591
V O=1V
0.6
-50
+3
%
0.609
V
+50
nA
Output Voltage Line Regulation
LNR
V IN = 2.5V to 5V
0.2
%/V
Output Voltage Load Regulation
LDR
IO=0A to 3A
0.5
%/A
42
Quiescent Current
IQ
No load
Shutdown Current
IS D
V E N = 0V
Current Limit
ILIM
Oscillator Frequency
fO SC
Drain-Source On-State Resistanc e
η
PSM Threshold
IT H
Analog Soft Start Time
tS
EN Threshold High
VE H
EN Threshold Low
VE L
EN Leakage Current
IE N
µA
1
µA
4
1.2
RDS (ON)
High Efficiency
90
1.5
A
1.8
High Side
85
mΩ
Low Side
60
mΩ
95
%
Vin=3.3V,Vo=1.2V,L=1uH
450
From enable to output
0.5
regulation
mA
ms
1.5
V IN =VEN = 0V
MHz
V
-1.0
0.3
V
1.0
µA
Over Temperature Protection
OTP
150
°C
OTP Hysteresis
OTH
30
°C
Power Analog Microelectronics, Inc
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11/2011 Rev1.2
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PAM2303
3A Low Noise Step-Down DC-DC Converter
Typical Performance Characteristics
TA =25 °C , CIN =33uF,Co=22 μF unless otherwise noted.
Efficienvy VS Input Voltage (Vo=1.2V)
Efficiency vs Output Current (Vo=1.2V)
100%
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
90%
80%
70%
60%
50%
40%
30%
3.3V
4.2V
5V
20%
10%
0%
1
10
100
1000
Output Current (m A)
10000
0.1A
1A
3A
2
Efficiency vs Output Current (Vo=1.8V )
70%
60%
50%
40%
30%
3.3V
4.2V
5V
0%
10
100
1000
10000
2
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
2.5
100
3
3.5
4
4.5
5
5.5
6
5.5
6
Efficienvy VS Input Voltage (Vo=3.3V)
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
4.2V
5V
5.5V
10
5
Input Voltage (V)
Efficiency vs Output Current (Vo=3.3V)
1
4.5
0.1A
1A
3A
Output Current (m A)
110%
100%
4
Efficienvy VS Input Voltage (Vo=1.8V)
80%
1
3.5
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
90%
10%
3
Input Voltage (V)
100%
20%
2.5
1000
10000
Output Current (mA)
0.1A
1A
3A
3
3.5
4
4.5
5
5.5
6
Input Voltage (V)
Power Analog Microelectronics, Inc
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11/2011 Rev1.2
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PAM2303
3A Low Noise Step-Down DC-DC Converter
Typical Performance Characteristics
TA =25 °C , CIN =33uF,Co=22 μF unless otherwise noted.
Output Voltage vs Output Current (Vo=1.2V)
Load Regulation (Vo=1.2V)
1.2
0.1%
1 .195
-0.1%
-0.3%
1.19
-0.5%
1 .185
-0.7%
1.18
-0.9%
1 .175
-1.1%
1.17
1 .165
3.3V
4.2V
-1.4%
5V
-1.8%
3.3V
4.2V
5V
-1.6%
-2.0%
1.16
0
5 00
1000
1500
2000
Output Current (mA)
2 500
1
3000
Output Voltage vs Output Current ( Vo=1.8V )
10
100
1000
Output Current (mA)
10000
Load Regulation (Vo=1.8V)
1.82
0.0%
-0.2%
1.81
-0.4%
-0.6%
1.8
-0.8%
1.79
-1.0%
-1.2%
1.78
-1.4%
3.3V
4.2V
5V
1.77
3.3V
4.2V
5V
-1.6%
-1.8%
1.76
-2.0%
0
500
1000 1500 2000
Output Current (mA)
2500
3000
1
10
100
1000
10000
Output Current (mA)
Output Voltage vs Output Current ( Vo=3.3V )
Load Regulation (Vo=3.3V)
3.29
0.1%
3.285
-0.2%
3.28
-0.4%
3.275
-0.6%
3.27
4.2V
5V
5.5V
3.265
-1.0%
3.26
0
500
4.2V
5V
5.5V
-0.8%
1000
1500
2000
2500
1
3000
10
100
1000
10000
Output Current (mA)
Output Current (mA)
Power Analog Microelectronics, Inc
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11/2011 Rev1.2
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PAM2303
3A Low Noise Step-Down DC-DC Converter
Typical Performance Characteristics
TA =25 °C , CIN =33uF,Co=22 μF unless otherwise noted.
Quiescent Current VS Input Voltage
Rdson VS Input Voltage
44
110
42
100
40
90
38
80
36
70
34
Vo1.2V
Vo1.8V
Vo3.3V
32
60
30
P-0.1A
N-0.1A
50
2
2.5
3
3.5
4
4.5
5
5.5
6
2
2.5
3
Input Voltage (V)
3.5
4
4.5
5
5.5
6
Input Voltage (V)
Oscillator Frequency VS Input Voltage
Oscillator Frequency VS Temperature
1.58
1.50
1.48
1.46
1.56
1.44
1.42
1.40
1.54
1.38
1.36
1.52
1.34
Io=3A
1.32
Vin=3.6V
1.30
1.50
2.5
3
3.5
4
4.5
5
5.5
20
40
Input Voltage(V)
60
80
100
120
140
Temperature(℃）
Reference Voltage VS Temperature
Reference Voltage VS Input Voltage
0.602
0.6
0.600
0.598
0.598
0.596
0.596
0.594
0.592
0.594
0.59
0.592
0.588
0.590
0.586
0.588
I =100mA
0.584
I =600mA
0.586
0.582
I =800mA
0.584
0.58
2
3
4
Input Voltage
5
6
25
50
75
100
125
150
Tem perature
Power Analog Microelectronics, Inc
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11/2011 Rev1.2
7
PAM2303
3A Low Noise Step-Down DC-DC Converter
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 Cin and Cout.
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 I RIPPLE(P-P) requirement. The
output ripple △Vout is determined by:
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 IN or Vout also increases
the ripple current as shown in equation 3A
reasonable starting point for setting ripple
current is △I L = 1.2A (40% of 3A).
DIL =
1
 VOUT 
V OUT 
1
(f )(L )
 V IN 
△Vout≈△IL(ESR+1/8fCout)
Where f = operating frequency, C OUT=output
capacitance and ΔI L = ripple current in the
inductor. For a fixed output voltage, the output
ripple is highest at maximum input voltage since
Δ IL increases with input voltage.
(1)
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.
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-resis tance inductor.
Vo
1.2V
1.5V
1.8V
2.5V
3.3V
L
1µH
1.5µH
2.2µH
2.2µH
3.3µH
When choosing the input and output ceramic
capacitors, choose the X5R or X7R dielectric
formul ations. These dielectrics have the best
temperature and voltage charac teristics of all
the ceramics for a given value and size.
C IN and C OUT Selection
Thermal consideration
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:
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.
2

VOUT (VIN - VO UT )


C IN required IRMS @ IOMAX
VIN
1
For continuous operation, the junction
temperature should be maintained below 125°C.
The power dissipation is defined as:
This formula has a maximum at V IN =2Vout,
w h e r e I R M S= I O U T/ 2 . T h i s s i m p l e w o r s t - c a s e
condition is com monly 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 advis able to further
derate the capacitor, or choose a capacitor rated
at a higher temperature than required. Consult
the manufac turer if there is any question.
VORDSONH + (VIN -VO )RDSONL
+ (tSW FSIO +IQ )VIN
VIN
I Q is the step-down converter quiescent current.
The term tsw is used to estimate the f ull load
step-down converter switching losses.
PD =IO
2
Power Analog Microelectronics, Inc
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11/2011 Rev1.2
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PAM2303
3A Low Noise Step-Down DC-DC Converter
For the condition where the step-down converter
is in dropout at 100% duty cycle, the total device
dis sipation reduces to:
In this mode, the device has two states, working
state and idle state. First, the device enters into
wor k in g s tat e c ont ro ll ed by in ter n al e r ro r
amplifier.When the feedback vol tage gets higher
than internal reference voltage, the device will
enter into low I Q 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.
2
PD =IO RDSON H +IQ VIN
Since R DS(ON), quiescent current, and switching
losses all vary with input voltage, the total losses
should be investigated over the complete input
voltage range. The maximum power dissipation
de pend s on th e ther ma l r esi sta nc e 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:
TJ(MAX) -TA
PD =
θJA
Where TJ(max) is the maximum allowable
junction temperature 125°C.T A is the ambient
temperature and θJA is the thermal resistance
from the junction to the ambient. Based on the
standard JEDEC for a two layers thermal test
board, the thermal resistance θJA of QFN3X3-16
68°C/W and SOP-8(EP) 90°C/W respectively.
The maximum power dissipation at T A = 25°C can
be calculated by following formula:
100% Duty Cycle Operation
As the input voltage approaches the output
voltage, the converter turns the P-chan nel
transistor continuously on. In this mode the
output voltage is equal to the input voltage min us
th e voltag e d rop ac ros s the P - c hannel
transistor:
V OUT = V IN –I LOAD (R dson + R L)
where R dson = P-channel switch ON resistance,
I L O A D = O ut pu t c u rr e n t, R L = I nd uc t or DC
resistance
UVLO and Soft-Start
P D =(125°C-25°C)/68°C/W=1.47W(QFN3X3-16)
P D=(125°C-25°C)/90°C/W=1.11W(SOP-8)
The reference and the circuit remain reset until
the VIN crosses its UVLO threshold.
Setting the Output Voltage
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.
The internal reference is 0.6V (Typical). The
output voltage is calculated as below:
The output voltage is given by Table 1.
 R1 
VO =0.6×1+
 R2 


Table 1: Resistor recommend for output voltage
setting
Vo
R1
R2
1.2V
150k
150k
1.5V
225k
150k
1.8V
300k
150k
2.5V
475k
150k
3.3V
680k
150k
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.
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.
Power Analog Microelectronics, Inc
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11/2011 Rev1.2
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PAM2303
3A Low Noise Step-Down DC-DC Converter
Ordering Information
PAM 2303 X X X xxx X
Shipping Package
Output Voltage
Number of Pins
Package Type
Pin Configuration
P in Configur ation
A Type
Package Type
Number of Pins
Output Voltage
J: QFN3X3-16
E: 16
ADJ: Adj
E: SOP-8(EP)
C: 8
ADJ: Adj
F: DFN3X3-10
G: 10
ADJ: Adj
16 pins
B Type
8 pins
C Type
10 pins
Part Number
Output Voltage
Package Type
Shipping Package
PAM2303AJEADJR
ADJ
QFN3X3-16
3,000 Units/Tape & Reel
PAM2303BECADJR
ADJ
SOP-8(EP)
2,500 Units/Tape & Reel
PAM2303CFGADJR
ADJ
DFN3X3-10
3,000 Units/Tape & Reel
Power Analog Microelectronics, Inc
www.poweranalog.com
11/2011 Rev1.2
10
PAM2303
3A Low Noise Step-Down DC-DC Converter
Outline Dimensions
SOP-8(EP)
Power Analog Microelectronics, Inc
www.poweranalog.com
11/2011 Rev1.2
11
PAM2303
3A Low Noise Step-Down DC-DC Converter
Outline Dimensions
DFN3X3-10
Power Analog Microelectronics, Inc
www.poweranalog.com
11/2011 Rev1.2
12
PAM2303
3A Low Noise Step-Down DC-DC Converter
Outline Dimensions
QFN3X3-16
DIMENSIONS (Millieters)
MIN
TYP
MAX
A
0.50
0.55
0.60
A1
0.00
0.02
0.05
A2
0.20
b
0.18
0.25
0.30
D
2.90
3.00
3.10
D1
1.55
1.70
1.80
E
2.90
3.00
3.10
E1
1.55
1.70
1.80
e
L
0.50BSC
0.30
0.40
N
16
aaa
0.08
bbb
0.10
0.50
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