PAM PAM2306LX1YPGH

PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
Features
General Description
n Efficiency up to 96%
n Only 40μA (Typ. per Channel) Quiescent
Current
n Output Current: Up to 1A per Channel
n Internal Synchronous Rectifier
n 1.5MHz Switching Frequency
n Soft Start
n Under-Voltage Lockout
n Short Circuit Protection
n Thermal Shutdown
n Small 12L WDFN3x3 Package
n Pb-Free Package and RoHS Compliant
The PAM2306 is a dual step-down current-mode,
DC-DC converter. At heavy load, the constantfrequency PWM control performs excellent
stability and transient response. To ensure the
longest battery life in portable applications, the
PA M 2 3 0 6 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.
The PAM2306 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 3.3V, 2.8V, 2.5V,
1.8V, 1.5V, 1.2V or adjustable. All versions
employ internal power switch and synchronous
rectifier for 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 0.1 μ A. Other key features
include under-voltage lockout to prevent deep
battery discharge.
Applications
n
n
n
n
n
Cellular Phone
Portable Electronics
Personal Information Appliances
Wireless and DSL Modems
MP3 Players
Typical Application
C OUT2
10μF
L2
V OUT2
PAM2306
V IN2
CIN2
4 7μF
1 VIN2
EN2 12
2
LX2
NC2 11
GND
FB2 10
3
R12
CFw1
100 pF
4
R11
R21
C FW2
100 pF
9
FB1
GND
5 NC1
LX1
6 EN1
VIN1 7
R22
8
C IN1
4.7 μF
V IN1
L1
V OUT1
C OUT1
10μF
(
VOUTx = VREF 1 + Rx1
Rx2
)
Figure 1. Adjustable Voltage Regulator
Power Analog Microelectronics , Inc
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07/2008 Rev 1.0
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PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
Typical Application
L2
V OUT2
V IN2
PAM2306
C IN2
4.7μF
1 VIN2
EN2 12
2
NC2 11
LX2
FB2 10
3 GND
4
C OUT2
10 μ F
FB1
GND
5 NC1
LX1
6 EN1
VIN1
9
8
7
C IN1
4.7μF
V IN1
L1
V OUT1
C OUT1
10μF
VOUTx = 1.2V,1.5V,1.8V,2.5V, 2.8V or 3.3V
Figure 2. Fixed Voltage Regulator
Block Diagram
SLOPE
COMP
OSC
FBx
R1
IAMP
-
PWM
COMP
MAIN
SWITCH ( PCH )
S Q
FREQ
SHIFT
+
R2
EA
COMP
SWITCHING
R Q
LOGIC
AND
RS LATCH
BLANKING
CIRCUIT
ANTI SHOOT THRU
0 . 6VREF
+
IRCMP
SHUTDOWN
LXx
SYNCHRONOUS
RECTIFIER ( NCH )
VIN
ENx
VINx
- + +
1 . 5M
OSC
+
GND
-
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PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
Pin Configuration and Marking Information
TOP VIEW
WDFN-12L 3x3
VIN2
1
12
EN2
LX2
2
11
NC2
GND
3
10
FB2
9
GND
FB1 4
NC1 5
2306v 1v 2
XXXYW
EN1 6
8
LX1
7
VIN1
v 1: Output Voltage 1
v 2: Output Voltage 2
(refer to “Ordering
Information”)
X: Internal Code
Y: Year
W: Week
GND
(Exposed Pad)
Pin No.
Pin Name
Pin Function
1
VIN2
Power Input of Channel 2.
2
LX2
Pin for Switching of Channel 2.
GND
Ground.The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
FB1
Feedback of Channel 1.
NC1,NC2
No Connection
6
EN1
Chip Enable of Channel 1 (Active High).VEN1≤VIN1.
7
VIN1
Power Input of Channel 1.
8
LX1
Pin for Switching of Channel 1.
10
FB2
Feedback of Channel 2.
12
EN2
Chip Enable of Channel 2 (Active High). VEN2≤VIN2.
3,9,
Exposed Pad
4
5,11
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PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
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 6.5V
En1, Fb1, Lx1, En2, Fb2 and LX2 Pin Voltage........
- 0 . 3V to ( V IN + 0 . 3V )
Junction Temperature................................150°C
Storage Temperature Range....... - 65°C to 150°C
Soldering Temperature.....................260°C , 10sec
Recommended Operating Conditions
Ambient Temperature Range......... - 40 °C to 85 °C
Junction Temperature Range.........-40°C to 125 °C
Supply Voltage...............................2.5V to 5.5V
Thermal Information
Parameter
Symbol
Package
Maximum
Unit
Thermal Resistance (Junction to ambient)
θJA
WDFN 3x3-12
60
°C/W
Thermal Resistance (Junction to case)
θJC
WDFN 3x3-12
8.5
°C/W
Power Dissipation
PD
WDFN 3x3-12
1.66
W
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PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
Electrical Characteristic
T A=25 OC, V IN=3.6V, V O=1.8V, C IN=10μF, C O=10μF, L=2.2μH, unless otherwise noted.
PARAMETER
SYMBOL
Test Conditions
MIN
Input Voltage Range
V IN
2.5
Regulated Feedback Voltage
VFB
0.588
TYP
0.6
Reference Voltage Line Regulation
ΔVFB
Regulated Output Voltage Accuary
VO
IO = 100mA
Peak Inductor Current
IPK
V IN =3V,V FB = 0.5V or VO=90%
1.5
MAX
UNITS
5.5
V
0.612
V
0.3
-3
%/V
+3
%
A
Output Voltage Line Regulation
LNR
V IN = 2.5V to 5V, IO =10mA
0.2
0.5
%/V
Output Voltage Load Regulation
LDR
IO=1mA to 1A
0.5
1.5
%
Quiescent Current (per channel)
IQ
No load
40
70
μA
Shutdown Current (per channel)
ISD
V EN = 0V
0.1
1
μA
Oscillator Frequency
fOS C
1.5
1.8
MHz
1.2
V FB = 0V or VO = 0V
500
kHz
P MOSFET
0.3
0.45
Ω
N MOSFET
0.35
0.5
Ω
ILSW
±0.01
1
μA
η
96
Drain-Source On-State Resistance
RDS(ON)
SW Leakage Current (per channel)
High Efficiency
V O = 100%
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
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PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
Typical Performance Characteristics
Efficiency vs Output Current (Vo=1.2V)
100
90
80
70
60
50
40
30
20
10
0
Efficiency vs Output Current (Vo=1.5V)
100
90
Efficiency(%)
Efficiency(%)
T A=25 °C , C IN=10 μ F, C O=10 μ F, L=4.7 μ H, unless otherwise noted.
70
60
50
40
Vin=3.6V
2.5V
3.6V
30
Vin=4.2V
4.2V
Vin=5V
1
80
20
10
100
1
1000
100
90
90
80
80
Efficiency(%)
Efficiency(%)
Efficiency vs Output Current ( Vo=1.8V )
100
70
60
50
3.6V
70
60
50
3V
3.6V
30
4.2V
4.2V
20
20
1
10
100
Output Current(mA)
1
1000
90
Efficiency(%)
80
70
60
50
40
3V
30
3.6V
4.2V
20
1
10
10
100
1000
Output Current(mA)
Efficiency vs Output Current (Vo=2.8V)
100
Efficiency(%)
1000
Efficiency vs Output Current ( Vo=2.5V )
40
2.5V
30
100
Output Current(mA)
Output Current(mA)
40
10
100
1000
100
90
80
70
60
50
40
30
20
10
0
Eifficiency VS Output Current (Vo=3.3V)
Vin=3.6V
Vin=4.2V
Vin=5V
1
Output Current(mA)
10
100
1000
Output Current(mA)
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PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
Typical Performance Characteristics
T A=25 °C , C IN=10 μ F, C O=10 μ F, L=4.7 μ H, unless otherwise noted.
100
90
90
80
80
Efficiency(%)
Efficiency(%)
Efficiency VS Input Voltage ( Vo=1.2V )
100
70
60
50
Efficiency vs Input Voltage ( Vo=1.5V )
70
60
50
10mA
Io=10mA
40
40
Io=100mA
100mA
800mA
Io=800mA
30
30
3
3.5
4
4.5
5
2.5
5.5
3
3.5
Efficiency vs Input Voltage ( Vo=1.8V )
100
100
90
90
80
80
Efficiency(%)
Efficiency(%)
4.5
5
5.5
Input Voltage(V)
Input Voltage(V)
70
60
Efficiency vs Input Voltage ( Vo=2.5V )
70
60
50
50
10mA
10mA
40
40
100mA
30
30
2.5
3
100mA
800mA
800mA
3.5
4
4.5
5
3
5.5
3.5
4
5
5.5
Eifficiency VS Input Voltage (Vo=3.3V)
Efficiency vs Input Voltage ( Vo=2.8V )
100
4.5
Input Voltage(V)
Input Voltage(V)
100
90
90
80
Eifficiency(%)
Efficiency(%)
4
70
60
50
10mA
40
100mA
80
70
60
50
40
30
20
Io=10mA
Io=100mA
10
800mA
Io=800mA
30
0
3
3.5
4
4.5
5
3.5
5.5
3.75
4
4.25
4.5
4.75
5
5.25
5.5
Input Voltage(V)
Input Voltage(V)
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PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
Typical Performance Characteristics
T A=25 °C , C IN=10 μ F, C O=10 μ F,L=4.7 μ H, unless otherwise noted.
Output Voltage VS Input Voltage
Reference Voltage VS Input Voltage
0.602
1.218
Vin=3.6V
0.600
1.213
Output Voltage(V)
0.598
Vfb(V)
0.596
0.594
0.592
0.590
0.588
I=100mA
1.203
1.198
Io=1mA
1.193
I=600mA
0.586
1.208
Io=500mA
Io=1A
I=800mA
1.188
0.584
2
3
4
Input Voltage(V)
5
6
2.5
3.5
4
5
5.5
Output Voltage VS Temperature
1.194
0.615
1.193
Output Voltage(V)
0.620
0.610
0.605
0.600
0.595
1.192
1.191
Vo=1.2V
1.19
Vin=3.6V
1.189
0.590
Io=100mA
1.188
0
50
100
20
150
40
60
80
100
120
140
Temperature(°C)
Tem perature(°C)
Output Voltage VS Load Current
Reference Voltage VS Load Current
0.603
1.218
Vo=1.2V
0.600
1.213
0.598
Output Voltage(V)
Reference Voltage(V)
4.5
Input Voltage(V)
Reference Voltage VS Temperature
Reference Voltage(V)
3
0.595
0.593
0.590
0.588
0.585
1.208
1.203
1.198
Vin=2.7V
Vin=3.6V
Vin=2.7V
1.193
Vin=3.6V
0.583
Vin=4.2V
Vin=5V
Vin=4.2V
0.580
1.188
0
200
400
600
800
0
1000
100 200 300 400 500 600 700 800 900 1000
Load Current(mA)
Load Current(mA)
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PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
Typical Performance Characteristics
O
T A=25 C, C IN=10 μ F, C O=10 μ F,L=4.7 μ H, unless otherwise noted.
Dynamic Supply Current VS Input Voltage
Dynamic Supply Current VS Temperature
60
Vo=1.2V
45
Dynamic Supply Current(uA)
Dynamic Supply Current(uA)
50
ILoad=0A
40
35
30
25
20
15
10
50
40
30
Vo=1.2V
20
Vin=3.6V
10
ILoad=0A
5
0
0
2.5
3
3.5
4
4.5
Input Voltage(V)
5
40
5.5
60
100
120
140
Rdson VS Temperature
R dson VS Input Voltage
0.6
0.4
Vin=3.6V
Vin=3.6V
0.35
0.5
0.3
0.4
Rds(on)
RDS(ON)
80
Temperature(°C)
0.25
0.3
0.2
0.2
0.15
0.1
0.1
0
Vin=4.2V
Vin=3.6V
Vin=2.7V
2
3
4
Input Voltage(V)
5
6
20
120
Oscillator Frequency VS Temperature
Oscillator Frequency VS Supply Voltage
1.58
1.8
Vin=3.6V
Vin=3.6V
Oscillator Frequency(MHz)
Oscillator Frequency(MHz)
70
Temperature(°C)
1.7
1.6
1.5
1.4
1.3
1.56
1.54
1.52
1.50
1.2
2
3
4
Supply Voltage(V)
20
5
40
60
80
100
120
140
Temperature(°C)
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PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
Typical Performance Characteristics
T A=25 °C ,C IN=10 μ F, C O=10 μ F,L=4.7 μ H, unless otherwise noted.
Load Transient
Io=0-500mA Vo=3.3V Vin=5V
Load Transient
Io=0-1A Vo=1.2V Vin=3.6V
Output
Current
Output
Current
Voltage
Output
Voltage
Output
Start-up from Shutdown
Vo=1.8V,Vin=3.6V
Voltage
Output
Enable
Inductor
Current
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PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
Application Information
The basic PAM2306 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 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 V IN or Vout also increases the
ripple current as shown in equation 1. A
reasonable starting point for setting ripple
current is △I L = 400mA (40% of 1A).
DIL =
1
æ VOUT ö
VOUT ç 1÷
f
L
VIN ø
( )( )
è
1 ö
æ
VVOUT @VIL ç ESR+
÷
8fCOUT ø
è
Where f = operating frequency, C OUT =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
Δ I L increases with input voltage.
Using Ceramic Input and Output Capacitors
(1)
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 1.4A rated inductor should be enough for
most applications (1A + 400mA). For better
efficiency, choose a low DC-resis tance inductor.
Vo
1.2V
1.5V
1.8V
2.5V
3.3V
L
2.2μH
2.2μH
2.2μH
4.7μH
4.7μH
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.
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:
é VOUT (VIN - VOUT )ùû
CIN required IRMS @ IOMAX ë
VIN
Thermal protection limits power dissipation in
the PAM2306. 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.
1
2
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 RMS= I OUT/ 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.
PD =IO 2
VORDSONH + (VIN -VO )RDSONL
VIN
+ (t SW FSIO +IQ )VIN
I Q is the step-down converter quiescent current.
The term tsw is used to estimate the full load
step-down converter switching losses.
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PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
100% Duty Cycle Operation
For the condition where the step-down converter
is in dropout at 100% duty cycle, the total device
dis sipation reduces to:
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
the voltage drop across the P - channel
transistor:
PD =IO 2RDSONH +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
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:
PD =
V OUT = V IN – I LOAD (R dson + R L)
where R dson = P-channel switch ON resistance,
I L O A D = Output current, R L = Inductor DC
resistance
UVLO and Soft-Start
TJ(MAX) -TA
The reference and the circuit remain reset until
the VIN crosses its UVLO threshold.
θJA
Where TJ(max) is the maximum allowable
junction temperature 125°C.T A is the ambient
temperature and θ JA 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 θ JA of DFN3X3 is
60°C/W. The maximum power dissipation at T A =
25°C can be calculated by following formula:
The PAM2306 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).
Short Circuit Protection
P D=(125°C-25°C)/60°C/W=1.66W
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 400kHz and minimum duty
cycle, therefore the average input current is
typically 200mA.
Setting the Output Voltage
The internal reference is 0.6V (Typical). The
output voltage is calculated as below:
æ R1 ö
VO=0.6×1+
ç R2 ÷
è
ø
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.
The output voltage is given by Table 1.
Table 1: Resistor selection for output voltage
setting
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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PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
PCB Layout Check List
When laying out the printed circuit board, the following checklist should be used to ensure proper
operation of the PAM2306. 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 FB pin connect directly to the feedback resistors? The resistive divider R1/R2 must be connected between the (+) plate of C OUT and ground.
3. Does the (+) plate 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 FB node.
5. Keep the (–) plates of C IN and C OUT as close as possible.
Top
Bottom
Figure 1 :PAM2306 Suggested Layout
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PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
Ordering Information
PAM 2306 X X X v 1 v 2
Output Voltage 2
Output Voltage 1
Number of Pins
Package Type
Pin Configuration
Pin Configuration
A Type
Package Type
Number of Pins
Y: WDFN 3x3
P: 12
Output Voltage
v1
v2
K: 3.3V
K: 3.3V
1. VIN2
H: 2.8V
H: 2.8V
2. LX2
G: 2.5V
G: 2.5V
3. GND
E: 1.8V
E: 1.8V
4. FB1
C: 1.5V
C: 1.5V
5. NC1
B: 1.2V
B: 1.2V
6. EN1
A: Adj
A: Adj
7. VIN1
8. LX1
9. GND
10. FB2
11: NC2
12 :EN2
Part Number
PAM2306AYPv1v2
Marking
2306v1v2
XXXYW
Package Type
Standard Package
WDFN3x3-12
3,000 Units/Tape&Reel
Power Analog Microelectronics , Inc
www.poweranalog.com
07/2008 Rev 1.0
14
PAM2306
Dual High-Efficiency PWM Step-Down DC-DC Coverter
Outline Dimensions
3x3 mm WDFN 12
2
1
2
1
DETAIL A
Pin #1 ID and Tie Bar Mark Options
Note :The configuration of the Pin #1 identifier is optional,
but must be located within the zone indicated.
Symbol
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
0.700
0.800
0.028
0.031
A1
0.000
0.050
0.000
0.002
A3
0.175
0.250
0.007
0.010
b
0.150
0.250
0.006
0.010
D
2.950
3.050
0.116
0.120
D2
2.300
2.650
0.091
0.104
E
2.950
3.050
0.116
0.120
E2
1.400
1.750
0.055
0.069
e
L
0.450
0.350
0.018
0.450
0.014
0.018
Power Analog Microelectronics , Inc
www.poweranalog.com
07/2008 Rev 1.0
15