PAM PAM2304

PAM2304
3MHz, 1A Step-Down DC-DC Converter
Features
General Description
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The PAM2304 is a step-down current-mode, DCDC converter. At heavy load, the constantfrequency P WM cont rol per for ms exc ellent
stability and transient response. To ensure the
longest battery life in portable applications, the
PA M 2 3 0 4 p r o v i d e s a p o w e r - s a v i n g P u l s e Skipping Modulation (PSM) mode to reduce
quiescent current under light load operation to
save power.
Efficiency up to 95%
Only 40 μA(TYP.) Quiescent Current
Output Current: Up to 1A
Internal Synchronous Rectifier
3MHz Switching Frequency
Soft Start
Under-Voltage Lockout
Short Circuit Protection
Thermal Shutdown
Small TSOT23-5, TDFN22-8 and
TDFN22-6 Packages
n RoHS Pass and Green Package
The PAM2304 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
output voltage is adjustable from 0.6V to the input
voltage. All versions employ internal power switch
and synchronous rectifierfor 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 1 μA.
Other key features include under-voltage lockout
to prevent deep battery discharge.
Applications
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Smart Phone
MID
Portable Electronics
Wireless Devices
Cordless Phone
Computer Peripherals
Battery Powered Widgets
Electronic Scales
Digital Frame
The PAM2304 is available in TSOT23-5, TDFN228 and TDFN22-6 packages.
Typical Application
V IN
C IN
10µF
L
1uH
VIN
Vo
SW
R1
GND
Cfw
100pF
Co
10µF
FB
R2
EN
R1 
V O = 0.6 
1+


 R2 
Power Analog Microelectronics, Inc
www.poweranalog.com
11/2011 Rev1.1
1
PAM2304
3MHz, 1A Step-Down DC-DC Converter
Block Diagram
3.0M
OSC
SLOPE
COMP
FREQ
SHIFT
OSC
+
IAMP
-
VIN
S Q
R Q
RS LATCH
-
FB
EA
+
VIN
SWITCHING
LOGIC
AND
BLANKING
CIRCUIT
MAIN
SWITCH( PCH)
ANTI SHOOT THRU
SW
SYNCHRONOUS
RECTIFIER (NCH )
COMP
EN
0.6VREF
+
IRCMP
-
SHUTDOWN
GND
Pin Configuration & Marking Information
Top View
TSOT23-5
EN 1
Top View
TDFN22-8
5 FB
GND 2
SW 3
4 VIN
FB
1
8
EN
AGND
2
7
NC
VIN
3
6
SW
PGND
4
5
SW
Top View
T DFN22-6
SW
1
6
GND
NC
2
5
VIN
FB
3
4
EN
CJ: Product Code
of PAM2304
V: Output Voltage
Y: Year
W: Week
Power Analog Microelectronics, Inc
www.poweranalog.com
11/2011 Rev1.1
2
PAM2304
3MHz, 1A Step-Down DC-DC Converter
Pin Description
TSOT23
TDFN22-8
TDFN22-6
Name
Function
1
8
4
EN
2
-
6
GND
3
5,6
1
SW
The drains of the internal main and synchronous power MOSFET.
4
3
5
VIN
Chip main power supply pin
5
1
3
FB
-
2
-
AGND
Analog ground.
-
4
-
PGND
Main power ground return pin.
-
7
2
NC
Enable control input. Force this pin voltage above 1.5V, enables
the chip, and below 0.3V s huts down the device.
Ground
Feedback voltage to internal error amplifier, the threshold voltage
is 0.6V.
No connected
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..................................-0.3V to 6.0V
EN, FB Pin Voltage.............................-0.3V to V IN
SW Pi n Voltage.....................-0.3V to ( V IN+0.3V )
Junction Temperature................................150°C
Storage Temperature Range........-65°C to 150°C
Soldering Temperature......................300°C , 5sec
Recommended Operating Conditions
Supply Voltage................................2.5V to 5.5V
Operation Temperature Range.........-40 °C to 85 °C
Junction Temperature Range........-40 °C to 125 °C
Thermal Information
Par ameter
Thermal Resistance
(Junction to Case)
Thermal Resistance
(Junction to Ambient)
Internal Power Dissipation
( TA=25°C)
Symbol
Package
TSOT23-5
θJC
θJA
PD
Note
Maximum
Unit
130
TDFN22-8
23.4
TDFN22-6
25
TSOT23-5
250
TDFN22-8
70
TDFN22-6
68
TSOT23-5
400
TDFN22-8
1400
TDFN22-6
980
°C/W
mW
Note:
The maximun output current for TSOT23-5 package is limited by internal power dissipation capacity a s
described in Application Information hereinafter.
Power Analog Microelectronics, Inc
www.poweranalog.com
11/2011 Rev1.1
3
PAM2304
3MHz, 1A Step-Down DC-DC Converter
Electrical Characteristic
TA =25 °C , VIN =3.6V, VO =1.8V, CIN =10µF, CO =10µF, L=1µH, unless otherwise noted.
PARAMETER
SYMBOL
Test Conditions
MIN
Input Voltage Range
VIN
2.5
Regulated Feedback Voltage
V FB
0.588
Reference Voltage Line Regulation
ΔVFB
Regulated Output Voltage Accuary
VO
Peak Induc tor Current
IPK
TYP
0.6
MAX
UNITS
5.5
V
0.612
V
0.3
IO = 100mA
-3
V IN= 3V ,V FB = 0.5V or
%/V
+3
1.5
V O=90%
%
A
Output V oltage Line Regulation
LNR
V IN = 2.5V to 5V, IO=10mA
0.2
0.5
%/V
Output V oltage Load Regulation
LDR
IO=1mA to 800mA
0.5
1.5
%
40
70
µA
1
µA
Quiescent Current
IQ
No load
Shutdown Current
ISD
V EN = 0V
Oscillator Frequency
fOS C
Drain-Source On-State Res istance
SW Leakage Current
High Effic iency
V O = 100%
3
MHz
V FB = 0V or VO = 0V
1
MHz
P MOSFET
0.3
0.45
Ω
N MOSFET
0.35
0.5
Ω
ILSW
±0.01
1
µA
η
95
RDS(O N)
IDS=100mA
%
EN Threshold High
V EH
1.5
V
EN Threshold Low
VE L
EN Leakage Current
IEN
±0.01
µA
Over Temperature Protection
OTP
150
°C
OTP Hysteresis
OTH
30
°C
0.3
V
Power Analog Microelectronics, Inc
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11/2011 Rev1.1
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PAM2304
3MHz, 1A Step-Down DC-DC Converter
Typical Performance Characteristics
TA =25 °C , CIN =10μF, CO =10μF, L=1 μH, unless otherwise noted.
Efficiency vs Output Current (Vo=1.2V)
1
Efficiency vs Output Current (Vo=1.5V)
1
0.9
0.9
0.8
0.8
0.7
0.7
0.6
0.6
0.5
0.5
0.4
0.4
0.3
0.3
0.2
2.5V
4.2V
5.5V
0.1
0.2
3.3V
5V
2. 5V
4. 2V
5. 5V
0.1
0
3.3V
5V
0
1
10
100
1000
1
100
1000
Out put Current (mA)
Output Current (mA)
Efficiency vs Output Current (Vo=1.8V )
Efficiency vs Output Current (Vo=2.5V )
1
1
0. 9
0.9
0. 8
0.8
0. 7
0.7
0. 6
0.6
0. 5
0.5
0. 4
0.4
0. 3
0.3
0. 2
2.5V
4.2V
5.5V
0. 1
10
0.2
3.3V
5V
3.3V
5V
0.1
0
4.2V
5.5V
0
1
10
100
1000
1
O utput Current (mA)
100
1000
Output Current (mA)
Eifficiency VS Output Current (Vo=3.3V)
Efficiency vs Output Current (Vo=2.8V)
1
10
1
0.9
0.9
0.8
0.8
0.7
0.7
0.6
0.6
0.5
0.5
0.4
0.4
0.3
0.3
0.2
0.2
3.3V
5V
0.1
4.2V
5.5V
4.2V
5.5V
0.1
0
5V
0
1
10
100
1000
1
Output Current (mA)
10
100
1000
Output Current (mA)
Power Analog Microelectronics, Inc
www.poweranalog.com
11/2011 Rev1.1
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PAM2304
3MHz, 1A Step-Down DC-DC Converter
Typical Performance Characteristics
TA =25 °C , CIN =10μF, CO =10μF, L=1μH, unless otherwise noted.
Efficiency VS Input Voltage (Vo=1.2V )
Efficiency vs Input Voltage ( Vo=1.5V )
1
1
0.9
0.9
0.8
0.8
0.7
0.7
0.6
0.6
0.5
0.5
0.4
0.4
0.3
0.3
1mA
0.1A
0.6A
0.2
0.1
0
2.5
3
3.5
4
10mA
0.3A
1A
4.5
5
1mA
0.1A
0.6A
0.2
0.1
0
2.5
5.5
3
3.5
4
10mA
0.3A
1A
4. 5
5
5.5
Input Voltage (V )
Input Voltage (V)
Efficiency vs Input Voltage ( Vo=1.8V )
1
1
0.9
0. 9
0.8
0. 8
0.7
0. 7
0.6
0. 6
0.5
0. 5
0.4
0. 4
Efficiency vs Input Voltage ( Vo=2.5V )
0. 3
0.3
0.2
1mA
10mA
0. 2
0.1
0.1A
0.6A
0. 3A
1A
0. 1
1m A
0.1 A
0.6 A
10mA
0.3A
1A
0
0
2.5
3
3.5
4
4.5
5
3
5. 5
3. 5
4
Input Volt age (V)
5
5.5
Eifficiency VS Input Voltage (Vo=3.3V)
Efficiency vs Input Voltage ( Vo=2.8V )
1
4.5
Input Volta ge (V )
1.1
1
0.9
0.9
0.8
0.8
0.7
0.7
0.6
0.6
0.5
0.5
0.4
0.4
0.3
0.3
0.2
1mA
10m A
0.1
0.1A
0.6A
0. 3A
1A
1mA
0. 1A
0. 6A
0.2
0.1
0
10mA
0.3A
1A
0
3
3.5
4
4. 5
5
5.5
3.5
Input Voltage (V)
4
4.5
5
5.5
Input Voltage (V)
Power Analog Microelectronics, Inc
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11/2011 Rev1.1
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PAM2304
3MHz, 1A Step-Down DC-DC Converter
Typical Performance Characteristics
TA =25 C, CIN =10 μF, CO =10 μF, L=1 μH, unless otherwise noted.
O
Quiescent Current VS Input Voltage
Oscillator Frequency VS Input Voltage
47
3.2
3
45
2.8
2.6
43
2.4
41
2.2
2
39
1.8
1.2V
1.8V
37
1. 5V
2. 5V
1.6
1.4
2.8V
35
1.2V
1.8V
1.5V
2.5V
2.8V
3.3V
1.2
2.5
3
3. 5
4
4. 5
5
5. 5
2.5
3
3.5
4
4.5
5
5.5
Input Voltage (V)
Inpu t Volta ge (V)
R dson VS Input Voltage
Rdson VS Temperature
0.4
0.6
0.35
0.5
0.3
0.4
0.25
0.3
0.2
0.2
0.15
0.1
0.1
0
Vin=3.6V
Vi n=4.2V
Vi n=3.6V
Vi n=2.7V
2
3
4
Input Voltage
5
6
20
70
Temperature(℃)
120
Power Analog Microelectronics, Inc
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11/2011 Rev1.1
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PAM2304
3MHz, 1A Step-Down DC-DC Converter
Application Information
The basic PAM2304 application circuit is shown
in Page 1. External component selection is
determined by the load requirement, selecting L
first and then Cin and Cout.
far exceeds the I RIPPLE (P-P) requirement. The
output ripple △ Vout is determined by:
1 

V VOUT @VI L 
ESR+

8fCO UT 

Inductor Selection
Where f = operating frequency, COUT =output
capacitance and Δ I L = ripple current in the
inductor. For a fixed output voltage, the output
ripple is highest at maximum input voltage since
ΔIL increases with input voltage.
For most applications, the value of the inductor
will fall in the range of 1µH. 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
V IN 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).
DIL =
1
 VOUT 
V OUT 
1
(f )(L )
 V IN 
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.
(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-resis tance inductor.
When choosing the input and output ceramic
capacitors, choose the X5R or X7R dielectric
formulations. These dielectrics have the best
temperature and voltage charac teristics of all
the ceramics for a given value and size.
CIN and COUT 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 PAM2304. 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 - VOUT )

CIN required IRMS @ I OMAX
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 IR MS = IOU 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 advisable 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.
The selection of Cout is driven by the required
effective series resistance (ESR).
PD =IO2
VO RDSON H +( VIN -VO )RDSONL
VIN
+ (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.
For the condition where the step-down converter
is in dropout at 100% duty cycle, the total device
dis sipation reduces to:
Typically, once the ESR requirement for Cout
has been met, the RMS current rating generally
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11/2011 Rev1.1
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PAM2304
3MHz, 1A Step-Down DC-DC Converter
100% Duty Cycle Operation
2
PD =IO RD SONH +IQ VIN
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 minus
th e voltag e d rop ac ros s the P - c hannel
transistor:
Since RDS(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
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
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 TSOT23-5
package is 250°C/W. The maximum power
dissipation at TA = 25°C can be calculated by
following formula:
The reference and the circuit remain reset until
the VIN crosses its UVLO threshold.
The PAM2304 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 acts as a digital circuit
to increase the switch current in several steps to
the P-channel current limit (1500mA).
P D=(125°C-25°C)/250°C/W=0.4W
Short Circuit Protection
Setting the Output Voltage
The switch peak current is limited cycle-by-cycle
to a typical value of 1500mA. In the event of an
output voltage short circuit, the device operates
with a frequency of 1MHz and minimum duty
cycle, therefore the average input current is
typically 200mA.
The internal reference is 0.6V (Typical). The
output voltage is calculated as below:
 R1 
VO =0.6×1+
 R2 


The output voltage is given by Table 1.
Thermal Shutdown
Table 1: Resistor selection for output voltage
setting
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.
Vo
R1
R2
1.2V
100k
100k
1.5V
150k
100k
1.8V
200k
100k
2.5V
380k
120k
3.3V
540k
120k
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PAM2304
3MHz, 1A Step-Down DC-DC Converter
PCB Layout Check List
When laying out the printed circuit board, the following checklist should be used to ensure proper operation of
the PAM2304. These items are also illustrated graphically in Figure 1. Check the following in your layout:
1. The power traces, consisting of the GND trace, the SW trace and the VIN trace should be kept short, direct
and wide.
2. Does the V FB pin connect directly to the feedback resistors? The resistive divider R1/R2 must be con nected
between the (+) plate of C OUT and ground.
3. Does the (+) plat e of CIN connect to VIN as closely as possible? This capacitor provides the AC current to
the internal power MOSFETs.
4. Keep the switching node, SW, away from the sensitive VFB node.
5. Keep the (–) plates of C IN and C OUT as close as possible.
Power Analog Microelectronics, Inc
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11/2011 Rev1.1
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PAM2304
3MHz, 1A Step-Down DC-DC Converter
Ordering Information
PAM 2304 X X X xxx
Output Voltage
Number of Pins
Package Type
Pin Configuration
Pin Configuration
A Type
5 pins
B Type
Package Type
Number of Pins
Output Voltage
A: TSOT-23
B: 5
ADJ: Adjustable
K: TDFN22-6
F: 6
G: TDFN22-8
C: 8
6 pins
C Type
8 pins
Part Num ber
Output Voltage
Package Type
Standard P ackage
PAM2304AABADJ
ADJ
TSOT-23-5
3,000Units/Tape&Reel
PAM2304BKFADJ
ADJ
TDFN22-6
3,000Units/Tape&Reel
PAM2304CGCADJ
ADJ
TDFN22-8
3,000Units/Tape&Reel
Power Analog Microelectronics, Inc
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11/2011 Rev1.1
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PAM2304
3MHz, 1A Step-Down DC-DC Converter
Outline Dimensions
TSOT23-5
D
e1
θ
L REF.
e
L1 (REF.)
b
REF.
A
A1
A2
c
D
E
E1
L
L1
θ
b
e
e1
Millimeter
Min
Max
1.10 MAX
0
0.10
0.70
1
0.12 REF.
2.70
3.10
2.60
3.00
1.40
1.80
0.45 REF.
0.60 REF.
0º
10º
0.30
0.50
0.95 REF.
1.90 REF.
Power Analog Microelectronics, Inc
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11/2011 Rev1.1
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PAM2304
3MHz, 1A Step-Down DC-DC Converter
Outline Dimensions
TDFN2x2-8
D
B
INDEX AREA
(D /2 xE /2 )
4
9
TOP VIEW
C
8
SEATING
PLANE
SIDE VIEW
0. 08 C
e
Nxb
Pin#1 ID
4
INDEX AREA
(D /2 xE /2 )
D2
BOTTOM VIEW
SYMBOL
A
A1
Lead
Pitch ( e)
0. 50
MIN
0. 70
0. 00
COMMON DIMENSION
NOM
MAX
0. 75
0. 80
0. 02
0. 05
Summary Table
Lead
Body
Count
Size
8
2X2
Pin # 1 ID
R0. 20
D BSC
E BSC
MIN
b NOM
MAX
MIN
D2 NOM
MAX
MIN
E2 NOM
MAX
MIN
L NOM
MAX
N
2. 00
2. 00
0 .18
0. 25
0. 30
1 .05
1 .20
1 .30
0 .45
0. 60
0. 70
0. 20
0. 30
0 .40
8
Unit: Millimeters
Power Analog Microelectronics, Inc
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11/2011 Rev1.1
13
PAM2304
3MHz, 1A Step-Down DC-DC Converter
Outline Dimensions
TDFN2x2-6
Power Analog Microelectronics, Inc
www.poweranalog.com
11/2011 Rev1.1
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