PAM PAM2421

PAM2421,PAM2422,PAM2423
3A,4.5A,5.5A PWM Step-Up DC/DC Converter
Features
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General Description
Greater than 90% Efficiency
Adjustable Output Voltage Up to 24V
Internal 24V Power MOSFET
Peak Current 3A,4.5A,5.5A
520kHz Frequency
Built-in Over-Voltage Protection (OVP)
Open Protection
Programmable Soft-Start Function
Thermal Shutdowns
Under-Voltage-Lockout
Over-Current Protection
SOP-8(EP) Package
The PAM242x devices are high-performance,fixed
frequency, current-mode PWM step-up DC/DC
converter that incorporate internal power
MOSFETs. The PAM242x includes an integrated
power MOSFET that supports peak currents of up
to 3A/4.5A/5.5A.
The PAM2 42x utilizes simple ex ternal loop
compensation allowing optimization between
component size, cost, and AC performance across
a wide range of applications. Additional functions
include an externally programmable soft-start
function for easy inrush current control, internal
over-voltage pr otection (OVP) ,c ycle-by- cyc le
current limit protection, under voltage lock-out and
thermal shutdown.
Applications
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TFT LCD Monitors
Battery-Powered Equipment
Set-Top Boxes
DSL and Cable Modems and Routers
The PAM242x is available in the small SOP-8(EP)
package.
Typical Application
SS34
L1
VIN
3.6V~5.5V
VOUT
12V/800mA
6.8 μH
C1
470μF
C2
10μF
PGND
C8
10nF
PAM242x
EN
FB
COMP
R3
51k
C5
470uF
R1
85k
SS
VIN
C3
1μF
C4
10uF
SW
AGND
C6
47pF
R2
10k
C7
2.2nF
Power Analog Microelectronics, Inc
www.poweranalog.com
02/2012 Rev1.1
1
PAM2421,PAM2422,PAM2423
3A,4.5A,5.5A PWM Step-Up DC/DC Converter
Block Diagram
Pin Configuration & Marking Information
Top View
SOP-8(EP)
PGND 1
8
SW
VIN 2
7
SS
EN 3
6
FB
COMP 4
5
AGND
PCN: Product Code of PAM242x
XXX: Internal Code
V:
Voltage Code
Y:
Year
W: Week
Power Analog Microelectronics, Inc
www.poweranalog.com
02/2012 Rev1.1
2
PAM2421,PAM2422,PAM2423
3A,4.5A,5.5A PWM Step-Up DC/DC Converter
Pin Descriptions
Pin Number
Name
Function
1
PGND
Power Ground
2
IN
Supply Input.
3
EN
4
COMP
Error Amplifier Compensation Node.
5
AGND
Analog Ground
6
FB
Enable Control. Connect to a logic high level to enable the IC. Connect to a logic low level
to disable the IC. When unused, connect EN pin to IN (do not leave pin floating).
Feedback Input. Connect this pin a res istor divider from the output to set the output
voltage. FB is regulated to 1.262V.
Sof t Start Control Input. Connect a capacitor from this pin to Ground to set soft-start
7
SS
timing duration. SS is discharged to ground in shutdown. SS may be left unconnected if
soft start is not desired.
8
SW
E xposed
PAD
Switch Output. Connec t this pin to the inductor and the schottky diode. To minimize E MI,
minimize the PCB trace path between this pin and the input bypass capac itor.
Connected to gound
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.
SW to Ground...................................–0.3V to 28V
VIN, EN, FB, SS, COMP to Ground........................
...................................................... –0.3V to 6.5V
Continuous SW Current..............Internally Limited
Operating Temperature Range.............................
................................................... –40
C to 150 
C
Storage Temperature Range......... –55 
C to 150C
Lead Temperature (Soldering, 10 sec) .......... 300 
C
Recommended Operating Conditions
Junction Temperature................... - 40℃ to 125℃
Ambient Temperature ..................... - 40℃ to 85 ℃
Thermal Information
Parameter
Thermal Resistance
(Junction to Case)
Thermal Resistance
(Junction to Ambient)
Package
Symbol
Maximum
SOP-8(EP )
θJC
75
Unit
℃/W
θJA
SOP-8(EP )
180
Power Analog Microelectronics, Inc
www.poweranalog.com
02/2012 Rev1.1
3
PAM2421,PAM2422,PAM2423
3A,4.5A,5.5A PWM Step-Up DC/DC Converter
Electrical Characteristic
At T A =25 
C ,V IN=V EN=5V,,unless otherwise specified.
CONDITIONS
PARAMETER
Input Voltage
Under Voltage Lockout
Thres hold
Under Voltage Lockout
Hysteresis
Quiescent Supply Current
Supply Current in S hutdown
Switching Frequency
MIN
2.7
VIN Rising
UNIT
5.5
V
2.5
V
200
mV
0.25
3
0.35
5
EN = Ground
0.1
520
1
1.262
1.287
V
0
0.05
80
0.15
nA
%/V
85
FB Feedback Voltage
1.237
VFB from 2.7V to 5.5V
PAM2421
Switch Current Limit
MAX
VFB = 1.4V, Not Switching
VFB = 1.0V, Switc hing
Maximum Dut y Cyc le
FB Input Current
FB Volt age Line Regulation
TYP
PAM2422
PAM2423
VIN=3.2V
Duty Cycle = 70%
uA
kHz
%
3
A
4.5
5.5
PAM2421
130
Switch On Res istance
PAM2422
100
Switch Leak age Current
PAM2423
VSW = 10V, EN = Ground
Soft Start Pin Bias Current
VSS = 1.2V
Logic High Threshold
Logic Low Threshold
EN Pin
EN Pin
mΩ
70
2
4.5
15
uA
7
uA
0.4
V
V
1.4
EN Pull Down Resistor
Thermal Shutdown
Temperature
Thermal Shutdown
Hysteresis
mA
1
MΩ
160
℃
40
℃
Power Analog Microelectronics, Inc
www.poweranalog.com
02/2012 Rev1.1
4
PAM2421,PAM2422,PAM2423
3A,4.5A,5.5A PWM Step-Up DC/DC Converter
Typical Operating Characteristics
At T A =25C ,VIN =VEN =5V,VFREQ =0V,unless otherwise specified.
Efficiency vs Output Current (Vo=12V)
Efficiency vs Output Current (Vo=15V)
100 %
100%
90 %
90%
80 %
80%
70 %
70%
60 %
60%
50 %
50%
40 %
40%
30 %
30%
20 %
10 %
Vin=3 .6V
Vin=4 .2V
Vin=5 V
20%
Vin=3.6V
Vin=4.2V
Vin=5V
10%
0%
0%
1
10
100
Lo ad Cu rren t (mA)
10 00
1
Efficiency vs Output Current (Vo=5V)
10
100
Lo ad Current (m A)
Efficiency vs Input Voltage (Vo=5V)
100%
1 00%
90%
90%
80%
80%
70%
70%
60%
60%
50%
50%
40%
40%
30%
Io=1m A
Io=10 mA
Io=10 0m A
Io=50 0m A
Io=1A
30%
V in=2. 7V
V in=3. 6V
V in=4. 2V
20%
10%
1 000
20%
10%
0%
0%
1
10
100
1000
O ut put Current (mA )
10000
2. 5
3
3 .5
4
4.5
5
Inp ut Vo lt ag e(V )
Efficiency vs Input Voltage (Vo=12V)
Efficiency vs Input Voltage (Vo=15V)
100%
1 00 %
90%
90 %
80%
80 %
70%
70 %
60%
60 %
50%
50 %
40%
40 %
1mA
10mA
100mA
500mA
1A
30%
20%
10%
30 %
1mA
10mA
100m A
500m A
20 %
10 %
0%
0%
3
3.5
4
4.5
5
5. 5
3
Inpu t Voltage (V)
3 .5
4
4 .5
Inp ut Vo lta ge (V)
5
5 .5
Power Analog Microelectronics, Inc
www.poweranalog.com
02/2012 Rev1.1
5
PAM2421,PAM2422,PAM2423
3A,4.5A,5.5A PWM Step-Up DC/DC Converter
Typical Operating Characteristics
At T A =25C ,VIN =VEN =5V,VFREQ =0V,unless otherwise specified.
Output Voltage vs Output Current (Vo=12V)
Output Voltage vs Output Current (Vo=15V)
12.5
15.5
12
15
11.5
14.5
11
14
10.5
Vin= 3. 6V
Vin= 4. 2V
Vin= 5V
13.5
V in= 4. 2V
V in= 5V
13
10
0
200
400
600
Load Current (mA )
800
0
1000
20 0
400
600
800
1000
L oad C urre nt (mA)
Quiescent Current (V FB=1.0V)
Quiescent Current (V FB=1.4V)
4
0.25
3. 5
0.2
3
2. 5
0.15
2
0.1
1. 5
1
0.05
0. 5
0
0
2
3
4
In put Voltage(V)
5
2
6
3
4
Inp u t Vo lta ge (V)
5
6
Power Analog Microelectronics, Inc
www.poweranalog.com
02/2012 Rev1.1
6
PAM2421,PAM2422,PAM2423
3A,4.5A,5.5A PWM Step-Up DC/DC Converter
Application Information
The PAM242x are highly efficient step -up DC/DC
converters that employ a currentmode,fixed
frequency pulse-width modulation (PWM)
architecture with excellent line and load
regulation.The PAM242x operate at constant
switching frequency under medium to high load
current conditions. At light loads, these devices
operate in a pulse-skipping mode in order to
improve light-load efficiency.
Open Protection
Soft-Start
Drive EN low to disable the IC and reduce the
su pply c urr ent to j ust 0.1 μA . As wi th al l
nonsynchronous step-up DC/DC converters, the
external Schottky diode provides a DC path from
the input to the output in shutdown. As a result,
the output drops to one diode voltage drop below
the input in shutdown.
Once the outputs achieve regulation, if the
voltage at FB falls below 0.2V the controller will
automatically disable, preventing the controller
from running open-loop and potentially
damaging the IC and load.
Shutdown
The PAM242x both offer a programmable softstart function which minimizes inrush current
during startup. The soft-start period is
programmed by connecting a 10nF capacitor
between SS and Ground. Operation of the softstart function is as follows: when the IC is
disabled, SS is actively discharged to Ground.
Upon enabling the IC, CSS is charged with a
4.5 μA current so that the voltage at SS increases
in a controlled manner. The peak inductor current
is limited by the voltage at SS, so that the input
current is limited until the soft-start period
expires, and the regulator can achieve its full
output current rating.
Thermal Shutdown
The PAM242x both feature integrated thermal
overload protection. Both devices are
automatically disabled when their junction
temperatures exceed 160°C, and automatically
re-enable when the die temperature decreases
by 40°C.
Setting the Output Voltage
The PAM242x both feature external adjustable
output voltages of up to 24V. To program the
output voltage, simply connect a resistive
voltage divider between the output, FB, and
G ND, wi th r es istor s s et acc ordi ng to the
following equation:
Where VFB is 1.262V.
Rectifier Selection
For optimal performance, the rectifier should be
a Schottky rectifier that is rated to handle both
the output voltage as well as the peak switch
current.
Over Voltage Protection
The PAM242x features internal automatic overvoltage protection, when feedback voltage is
higher than 115%.
Power Analog Microelectronics, Inc
www.poweranalog.com
02/2012 Rev1.1
7
PAM2421,PAM2422,PAM2423
3A,4.5A,5.5A PWM Step-Up DC/DC Converter
Ordering Information
PAM 242x X X X xxx X
Shipping Package
Output Voltage
Number of Pins
Package Type
Pin Configuration
Pin Configuration
A Type
Package Type
Number of Pins
E: SO P-8(EP)
C: 8
Output Voltage
ADJ: Adjustable
Part Number
Peak Current
Package Type
Shipping Package
PAM2421AECADJR
3A
SOP-8(EP)
2,500 Units/Tape & Reel
PAM2422AECADJR
4.5A
SOP-8(EP)
2,500 Units/Tape & Reel
PAM2423AECADJR
5.5A
SOP-8(EP)
2,500 Units/Tape & Reel
Power Analog Microelectronics, Inc
www.poweranalog.com
02/2012 Rev1.1
8
PAM2421,PAM2422,PAM2423
3A,4.5A,5.5A PWM Step-Up DC/DC Converter
Outline Dimension
SOP-8(EP)
Power Analog Microelectronics, Inc
www.poweranalog.com
02/2012 Rev1.1
9