PAM PAM2842RGR

PAM2842
High Power LED Driver
Features
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Description
Output Power up to 30W
Chip Enable with Soft-start
Analog and PWM Dimming
Peak Efficiency up to 97%
Low Quiescent Current
Switching Frequency Adjustable
Support Buck/Boost/Sepic Topology
Over Current Protection
Over Voltage Protection
Thermal Protection
UVLO
Tiny Pb-Free Packages :
40-Pin QFN6x6 and TSSOP-20
The PAM2842 is a high power LED driver,
capable of driving up to 10 high power LEDs in
series. The PAM2842 supports buck, boost and
sepic topology.
The PAM2842 features over current protection ,
over voltage protection , under voltage lockout
and over temperature protection, which prevent
the device from damage.
LED dimming can be done by using a PWM signal
to the COMP pin.
The PAM2842 is available in 40-Pin QFN6x6 and
TSSOP-20 packages.
Applications
n Home Lighting
n Automotive Lighting
n Monitor Backlighting
Typical Application Circuit
Boost with Low Side Current Sense
Vin
Boost with High Side Current Sense
L1
Vin
L1
33 μ H
1μF
1μF
PGND
SW
PGND
OV
PAM2842
RT
1μF
1μF
VDD-5V
VDD-DR
10 μ F
430kΩ
SW
HVIN
EN
0.14Ω
33 μ H
130kΩ
AGND
1k Ω
PGND
SW
PGND
SW
OV
HVIN
15kΩ
EN
10nF
COMP
Sense+
PAM2842
VDD-DR
Sense-
1μF
1μF
15kΩ
VDD-5V
10 μ F
0.14Ω
430kΩ
RT
Sense+
AGND
Sense-
130kΩ
1k Ω
10nF
COMP
Power Analog Microelectronics , Inc
www.poweranalog.com
09/2008 Rev 1.1
1
PAM2842
High Power LED Driver
Typical Application Circuit
Buck/Boost (Sepic) with High Side Current Sense
Buck/Boost (Sepic) with Low Side Current Sense
Vin
L1
Vin
10 μ F
0.14Ω
47 μ H
47 μ H
1μF
47 μ H
PGND
1μF
L2
SW
PGND
SW
HVIN
OV
EN
56kΩ
L1
220kΩ
1μF
PAM2842
PGND
SW
PGND
SW
HVIN
OV
12kΩ
VDD-5V
VDD-DR
EN
1k Ω
47 μ H
10nF
220kΩ
1μF
12kΩ
VDD-5V
PAM2842
VDD-DR
COMP
L2
1k Ω
10nF
COMP
10 μ F
10 μ F
RT
1μF
Sense+
1μF
130kΩ
0.14Ω
Sense-
AGND
RT
Sense+
AGND
Sense-
130kΩ
Buck with High Side Current Sense
Vin
0.14Ω
10 μ F
1μF
PGND
SW
PGND
SW
L
OV
HVIN
EN
10 μ F
1μF
47 μ H
1nF
NC
VDD-5V
PAM2842
VDD-DR
COMP
RT
Sense+
AGND
Sense-
130kΩ
1k Ω
100nF
12kΩ
Power Analog Microelectronics , Inc
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09/2008 Rev 1.1
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PAM2842
High Power LED Driver
Block Diagram
VDD_5V
HVIN
COMP
OV
SW SW
Comparator
LDO1
PWM
+
LDO2
PWM Logic
And Driver
VDD-DR
+
Σ
100mV
Reference
Sense+
+
GM
-
CS
Ramp
Generator
FB
SenseEN
Shutdown And
Soft-start
AGND
Adjustable
Oscillator
RT
PGND PGND
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09/2008 Rev 1.1
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PAM2842
High Power LED Driver
Pin Configuration & Marking Information
TOP View
TSSOP-20
NC
NC
NC
NC
NC
NC
NC
NC
40
NC
NC
Top View
6mm*6mm QFN
39
38
37
36
35
34
33
32
31
1
20
NC
PGND
2
19
SW
SW
PGND
3
18
SW
28
SW
PGND
4
17
SW
27
SW
HVIN
5
16
OV
EN
6
15
VDD_5V
VDD-DR
7
14
COMP
RT
8
13
Sense+
AGND
9
12
Sense-
PGND
10
11
PGND
1
30
SW
PGND
2
29
PGND
3
PGND
4
PGND
5
PGND
6
PAM2842
XXXYWWLL
26
SW
25
SW
NC
10
21
VDD_5V
13
14
15
16
17
18
19
20
NC
VDD-DR
NC
NC
NC
22
COMP
9
NC
EN
Sense+
OV
Sense-
23
AGND
8
12
HVIN
RT
24
11
7
NC
NC
Pin Number
PAM2842
XXXYWWLL
PGND
PGND
X: Internal Code
Y: Year
WW: Week
LL: Internal Code
Name
Description
QFN 6x6-40
TSSOP-20
1-6
1,2,3,4,10,11
PGND
Power Ground
8
5
HVIN
Input
9
6
EN
Chip Enable, Active High
10
7
VDD-DR
Internal LDO Output
12
8
RT
Frequency Adjustment Pin
13
9
AGND
Analog Ground
14
12
Sense-
Sense resistor -
15
13
Sense+
Sense resistor +
17
14
COMP
Compensation Node
21
15
VDD_5V
Internal LDO Output
23
16
OV
Over Voltage
25-30
17,18,19
SW
Drain of Main Switch.
7,11,16,18-20,22,24,31-40
20
NC
No Connect
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09/2008 Rev 1.1
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PAM2842
High Power LED Driver
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 .
Storage Temperature................ .....-40 OC to 125 OC
Maximum Junction Temperature..................150 OC
Soldering Temperature.......................300 OC, 5sec
Supply Voltage.............................................40V
Output Current................................................1A
I/O Pin Voltage Range.........GND-0.3V to V DD+0.3V
Recommended Operating Conditions
O
Supply Voltage Range.........................5.5V to 40V
O
O
Operation Temperature Range..........-40 C to 85 C
O
Junction Temperature Range......... .-40 C to 150 C
Thermal Information
Parameter
Thermal Resistance
(Junction to Case)
Thermal Resistance
(Junction to Ambient)
Symbol
θJC
θJA
Package
Maximum
TSSOP
20
QFN 6mm*6mm
7.6*
TSSOP
90
QFN 6mm*6mm
18.1*
Unit
°C/W
*The Exposed PAD must be soldered to a thermal land on the PCB.
Power Analog Microelectronics , Inc
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09/2008 Rev 1.1
5
PAM2842
High Power LED Driver
Electrical Characteristic
V EN=V DD=24V, 1Wx10 LEDs, T A=25°C, unless otherwise noted .
PARAMETER
Conditions
Input Voltage Range
Quiescent Current
Min
Typ
5.5
Max
Units
40
V
2
mA
ENA=high (no switching)
1
ENA =high (1M switching frequency)
6
mA
ENA =high (500k switching frequency)
3
mA
ENA =high (200k switching frequency)
1.6
mA
ENA =low
5
10
μA
Feedback Voltage, Low Side
V FB =VSENSE+ -AGND, VSE NSE-=AGND
95
100
105
mV
Feedback Voltage, High Side
V FB =VSENSE+ - V SENS E-
95
100
105
mV
LED Current Line Regulation
IO=350mA
LED Current Load Regulation
0.02
%/V
1.0
%
LDO Stage
VDD_5V
No switching
4.5
5
5.5
V
VDD_5V current_limit
No switching
14
74
90
mA
VDD_5V UVLO Threshold
No switching
3.7
4.0
4.3
V
VDD_5V UVLO Hysteresis
No switching
VDD_DR
No switching
4.5
5
5.5
V
VDD_DR current_limit
No switching
14
50
90
mA
VDD_DR UVLO Threshold
No switching
3.7
4.0
4.3
V
VDD_DR UVLO Hysteresis
No switching
200
mV
200
mV
0.1
Ω
Switch Current Limit
3.5
A
Switch Leakage Current
50
μA
Switch Stage
Switch Rdson
RT Voltage
Switching Frequency*
VDD_5V=5V
R RT =71kΩ
1.1
1.2
1.3
V
R RT =30kΩ
800k
1M
1.2M
Hz
R RT =71kΩ
400
500
600
kHz
R RT =180kΩ
160
200
240
kHz
F SW =1MHz
10
%
F SW =500kHz
5
%
F SW =200kHz
2.5
%
Low Side Sense
95
%
High Side Sense
100
%
Vc Source Current
Feedback voltage=0
30
μA
Vc Sink Current
Feedback voltage=0
30
μA
Min Duty Cycle
Max Duty Cycle
* Switching Frequency FSW =
12
10
, reference value
24 ´ (RRT + 12k )
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09/2008 Rev 1.1
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PAM2842
High Power LED Driver
Electrical Characteristic
V EN=V DD=24V, 1Wx10 LEDs, T A=25 °C , unless otherwise noted .
PARAMETER
Conditions
Min
Typ
Max
Units
1.1
1.2
1.3
V
Fault Protection
OV threshold Voltage
OV Hysteresis
70
mV
Thermal-Shutdown
150
°C
Thermal-Shutdown Hysteresis
30
°C
Control Interface
EN High
1.5
EN Low
V
0.4
V
Power Analog Microelectronics , Inc
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09/2008 Rev 1.1
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PAM2842
High Power LED Driver
Typical Performance Characteristic
Boost mode, V EN=V DD=24V, 3W LED, Fsw=200kHz, T A=25 °C, unless otherwise noted .
2. Shutdown Current vs Input Voltage
1. Efficiency vs Input Voltage
(Po=30W, 10X3W LEDs)
6
98%
5
Shutdown Current (uA)
Efficiency
97%
96%
95%
94%
4
3
2
1
0
93%
10
15
20
25
30
0
5
10
Input Voltage (V)
20
25
30
35
Input Voltage (V)
3. Quiescent Current vs Input Voltage
1.8
800
4. Output Current vs Input Voltage
(10X3W LEDs)
700
Output Current (mA)
1.6
Quiescent Current (mA)
15
1.4
1.2
1
0.8
Switching
600
500
400
300
200
Low side Current sense
100
No Switching
0.6
High side Current sense
0
0
5
10
15
20
25
30
35
10
Input Voltage (V)
15
20
25
30
Input Voltage (V)
5. Output Current vs Temperature
(V IN=12V, Load=10X3W LEDs)
800
Output Current (mA)
750
700
650
600
550
500
450
400
0
20
40
60
80
100
Ambient Temperature (℃)
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09/2008 Rev 1.1
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PAM2842
High Power LED Driver
Typical Performance Characteristic
Fsw=300kHz, T A=25°C, unless otherwise noted .
6. Efficiency vs Input Voltage
(Sepic mode, 1W LED),
400
90%
350
89%
88%
300
87%
250
Efficiency
Output Current (mA)
5. Output Current vs Input Voltage
(Sepic mode, 1W LED),
200
150
86%
85%
84%
100
50
5*1W
4*1W
3*1W
2*1W
83%
5*1W
3*1W
1*1W
82%
1*1W
0
4*1W
2*1W
81%
5
10
15
5
20
7
9
Input Voltage (V)
13
15
17
19
35
40
8. Efficiency vs Input Voltage
(Buck mode, 3W LED),
7. Output Current vs Input Voltage
(Buck mode, 3W LED),
100%
0.8
0.7
95%
0.6
90%
0.5
Efficiency
Output Current (A)
11
Input Voltage (V)
0.4
0.3
85%
80%
0.2
75%
0.1
1*3W
3*3W
70%
0
5
10
15
20
25
30
35
40
5
Input Voltage (V)
400
2*3W
10
15
20
25
30
Input Voltage (V)
10. Start up and Shutdown
9. LED Current vs Duty Cycle
(PWM=100Hz, in Dimming State)
LED Current (mA)
350
300
Vout
250
EN
200
150
Vcomp
100
50
0
0
20
40
60
80
100
Duty Cycle (%)
Power Analog Microelectronics , Inc
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09/2008 Rev 1.1
9
PAM2842
High Power LED Driver
Application Information
Topology Selection
For the large power application, if chose DCM, the
peak current will be very large, it will have great
electrical stress on the components, so we chose
CCM.
When maximum power supply voltage is below
than minimum load voltage, select the boost
topology. When minimum power supply voltage is
high than maximum load voltage, select buck
topology. When load voltage range is small and
between the power supply voltage, select sepic
topology.
When work in CCM mode, a reasonable ripple
current is chosen to
Δ I L=0.4I L
For the boost topology,
Table-1: Voltage condition Vs Topology
Condition
Topology
Vin max < Vo min
Boost
Vinmin > Vomax
Buck
Vo Ì Vin
Sepic
IL =
D=
The inductance, peak current rating, series
resistance, and physical size should all be
considered when selecting an inductor. These
factors affect the converter's operating mode,
efficiency, maximum output load capability,
transient response time, output voltage ripple,
and cost.
VO - VIN
VO
VIN (VO - VIN )
LFVO
DIL =
Inductor Selection
IO
1- D
D: duty cycle, Io: output current, F: switching
frequency.
From above equation we can get the inductance:
L=
The maximum output current, input voltage,
output voltage, and switching frequency
determine the inductor value. Large inductance
can minimizes the current ripple, and therefore
reduces the peak current, which decreases core
losses in the inductor and I2R losses in the entire
power path. However, large inductor values also
require more energy storage and more turns of
wire, which increases physical size and I2R
copper losses in the inductor. Low inductor values
decrease the physical size, but increase the
current ripple and peak current. Finding the best
inductor involves the compromises among circuit
efficiency, inductor size, and cost.
2.5VIN2 (VO - VIN )
FIO VO2
The inductor's current rating should be higher
IL +
than
DIL
2
For the buck topology, I L=I O
D=
DIL =
so
When choosing an inductor, the first step is to
determine the operating mode: continuous
conduction mode (CCM) or discontinuous
conduction mode (DCM). When CCM mode is
chosen, the ripple current and the peak current of
the inductor can be minimized. If a small-size
inductor is required, DCM mode can be chosen. In
DCM mode, the inductor value and size can be
minimized but the inductor ripple current and peak
current are higher than those in CCM.
L=
VO
VIN
(VIN - VO )VO
LFVIN
2.5VO (VIN - VO )
FIO VIN
For the sepic topology, L1=L2
D
IL1 = IO
1- D
I L2=I O
D=
VO
VIN + VO
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09/2008 Rev 1.1
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PAM2842
High Power LED Driver
DIL =
Chose
so
VIN VO
LF(VIN + VO )
The ripple voltage is
IOD
FCS
The voltage rating must be higher than input
voltage.
DVCs =
Δ I L=0.4I L1
L=
2.5VIN2
FIO (VIN + VO )
Because the Cs capacitor will flow the large RMS
current, so this topology is suitable for small
power application.
Capacitor Selection
An input capacitor is required to reduce the input
ripple and noise for proper operation of the
PAM2842. For good input decoupling, Low ESR
(equivalent series resistance) capacitors should
be used at the input. At least 10 μ F input capacitor
is recommended for most applications. And close
the IC Vin-Pin we should add a bypass capacitor,
usually use a 1 μ F capacitor.
Diode Selection
PAM2842 is a high switching frequency converter
w h i c h d e m a n d s h i g h s p e e d r e c t i f i e r. I t ' s
indispensable to use a Schottky diode rated at 3A,
40V with the PAM2842. Using a Schottky diode
with a lower forward voltage drop is better to
improve the power LED efficiency.
A minimum output capacitor value of 10 μ F is
recommended under normal operating
conditions, while a 22 μ F or higher capacitor may
be required for higher power LED current. A
reasonable value of the output capacitor depends
on the LED current. The total output voltage ripple
has two components: the capacitive ripple caused
by the charging and discharging on the output
capacitor, and the ohmic ripple due to the
capacitor's equivalent series resistance. The ESR
of the output capacitor is the important parameter
to determine the output voltage ripple of the
converter, so low ESR capacitors should be used
at the output to reduce the output voltage ripple.
The voltage rating and temperature
characteristics of the Output capacitor must also
be considered. So a value of 10 μ F, 50V voltage
rating capacitor is chosen.
In boost topology, the voltage rating should be
higher than Vout and in buck topology, the voltage
rating higher than Vin, the peak current is
IDMAX = IL +
in sepic topology, the voltage rating should be
higher than Vin+Vout, the peak current is
I DMAX=I L1peak+I L2peak
The average current of the diode equals to Io.
Work frequency selection
PAM2842 working frequency is decided by
resistor connect to the RT pin, it can be calculated
by follow equation:
1012
FSW =
(Hz)
24 ´ (RT + 12K)
Consider from discharge aspect: Ix Δ t=Cx Δ V
In boost and sepic topology, CO =
In buck topology, CO =
DIL
2
IOD
FVRIPPLE
From the equations, we can see when working
frequency is high, the inductance can be small.
It's important in some size limit application. But
we should know when the working frequency is
higher, the switching loss is higher too. We must
pay attention to thermal dissipation in this
application.
IO (1 - D)
FVRIPPLE
V RIPPLE: Output voltage allowable ripple.
Consider from equivalent series resistance:
Methods for Setting LED Current
V ripple-esr=I co.ripplexC oesr
There are two methods for setting and adjusting
the LED current:
1) Rsense only
2) PWM signal with external components
a) Use the COMP pin
b) Use the Sense pin
In sepic topology, there is a series capacitor Cs
between L1 and L2 (see application schematic), it
flows the current:
VO
ICs(RMS) = IO
VIN
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PAM2842
High Power LED Driver
It maybe generate the audible noise in this
dimming condition.
l Method 1: LED Current Setting with Resistor
Rsense
l Method 3: LED Current Setting with PWM
Signal using Sense Pin
The most basic means of setting the LED current
is connecting a resistor between Rsense+ and
Rsense-. The LED current is decided by ISET
Resistor Rsense.
This method is turn PWM signal to DC voltage, the
output current can be adjusted. Because the LED
current is a adjustable DC value, it will cause LED
color drift.
I LED =0.1/ R sense
For flowing the large current, must pay attention
to power dissipation on the resistor.
Low side current sense and high side current
sense circuit is different. Please see Figure 2 and
3. It use the internal reference voltage, so PWM
dimming signal voltage is not considered, just
meet the request of the MOSFET driving voltage.
Rsense has two position to select: high side
current sense and low side current sense. In buck
topology it just has high side current sense. In
other topology we recommend use low side
current sense for easier PCB layout.
VDD_5V
l Method 2: LED Current Setting with PWM
Signal Using COMP Pin
R1
D1
R2
This circuit uses resistor Rsense to set the on
state current and the average LED current, then
proportional to the percentage of off-time when
the COMP pin is logic high. Here use a invert
component 2N7002 (Q1) to isolate and invert the
PWM signal (See Figure 1).
Q1
C1
PWM-DIM
R3
Sense+
R4
RTN
RSense
C2
Figure 2. PWM Dimming Use Sense Pin in Low
Side Current Sense
PAM2842
COMP
RSense
Vo
Sense+
Q1
VDD_5V
2N7002
R3
PW M signal
Sense-
R1
D1
Ton
Q2
Toff
Q1
Figure 1. PWM Dimming Use COMP Pin
PWM-DIM
Average LED current is approximately equal to:
T I
IAVG = OFF LED
TON + TOFF
R5
C1
R4
Figure 3. PWM Dimming Use Sense Pin in High
Side Current Sense
Also, the recommended PWM frequency is
between 100Hz and 200Hz.
The RC filter (R1,R2,C1,C2) value is decided by
dimming frequency, the divider resistor (R3,R4) is
decided by dimming range.
Frequency <100Hz can cause the LEDs to blink
visibly. As the COMP pin connects to a capacitor,
it needs rise time. If frequency >200Hz, the
average LED current will have a large error when
duty cycle is small (<50%).
Because final adjusted is a DC value, this method
can avoid audible noise effectively and achieve
better EMI performance than the second method.
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PAM2842
High Power LED Driver
Setting the Output Limit Voltage
Vout
The OV pin is connected to the center tap of a
resistive voltage divider from the high-voltage
output to ground (see application schematic).
R
VOUT -Limit = VOV (1 + UP )
RDOWN
COMP
ZENER
Q
R
The recommend procedure is to choose R3
=360K and R4 =12K to set Vout_limit =37.2V.
In boost and sepic circuit, when LED open or no
load, the circuit will have no feedback, if no other
measure be taken the switch voltage will be very
high and damage the switch, so this OV pin must
be set carefully.
Figure 5: Use External Zener
Note: The output limit voltage must be set higher
than working output voltage by a proper value, or
it will work abnormal in low temperature or some
other conditions.
In buck circuit, the switch voltage is always small
than input voltage, so the OV pin setting is not
important in this condition.
Short LED Function
This OV pin is used to limit output voltage to avoid
breakdown of the switch other than to regulate
output voltage. The setting value must keep the
switch voltage below 40V.
PAM2842 is a constant current driver. When one
or more LED shorted, the circuit will still work, the
output voltage is decided by LED numbers. In
boost topology, make sure the output voltage is
higher than input voltage; otherwise the unlimited
current will directly go through supply to LED and
damage the LED.
In sepic circuit, one must notice that the switch
voltage equals Vin+Vo.
This OV pin has a hysteresis voltage detect
function, not latch-up function, so output voltage
will have a overshoot when no load or load
working voltage is high than setting limit voltage.
If the component parameter not match
appropriately, the overshoot voltage will be too
high and can demage the switch.
Power Dissipation
As PAM2842 integrates a power MOSFET, the
power dissipation must be considered. To a
MOSFET the power loss includes 5 sections, turn
on loss, turn off loss, conduction loss, drive loss
and output capacitor Coss loss.
1
Pturn-on = Iturn-on VOUT Tr f
2
Several methods can decrease the overshoot
voltage:
(1)
Add a small capacitor (<100pF) parallel
with the up divider resistor (See Figure 4).
(2)
Use external zener to clamp the output
peak voltage (See Figure 5).
1
Pturn-off = Iturn-off VOUT Tr f
2
2
PRDson = IRMS
RDSon
Vout
PDrive = QgUDrive f
R3
Cf
PCoss =
OV
1
2
COSS VOUT
f
2
PSwitch = Pturn-on + Pturn-off + PRDSon + Pdrive + PCoss
R4
DT = q jaPswitch
Tr: switch rise time. Tf: switch fall time. U Drive: gate
drive voltage. θ ja is relative with IC package,
heat-sink area and air flow condition etc.
Figure 4: add forward capacitor
Power Analog Microelectronics , Inc
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09/2008 Rev 1.1
13
PAM2842
High Power LED Driver
Above description does not consider the IC
control power, so the total power will be more than
calculated value.
the input and output capacitor ground and PGND
pin. Connect all these together with short, wide
traces or a small ground plane. Maximizing the
width of the power ground traces improves
efficiency and reduces output-voltage ripple and
noise spikes. Create an analog ground island
(AGND) consisting of the output voltage
detection-divider ground connection, the Sensepin connection, VCC-5V and VCC-driver
capacitor connections. Connect the device's
exposed backside pad to PGND. Make sure no
other connections between these separate
ground planes.
PAM2842 has over-temperature protection. When
junction temperature is over 150°C, it will shut
down and auto restart when junction temperature
decrease below 120 °C .
In high temperature circumstance application,
one must pay attention to heat dissipation, or it
will shut down and restart. It is recommended to
use external heat-sink and placed near to the IC
surface.
4) Place the output voltage setting-divider
resistors as close to the OV pin as possible. The
divider's center trace should be kept short. Avoid
running the sensing traces near SW Pin.
PCB Layout Guidelines
Careful PCB layout is important for normal
operation. Use the following guidelines for good
PCB layout: (BOOST)
5) Place the VIN pin bypass capacitor as close
to the device as possible. The ground connection
of the VIN bypass capacitor should be connected
directly to GND pins with a wide trace.
1) Minimize the area of the high current
switching loop of the rectifier diode and output
capacitor to avoid excessive switching noise.
6) Minimize the size of the SW node while
keeping it wide and short. Keep the SW node
away from the feedback node. If possible, avoid
running the SW node from one side of the PCB to
the other.
2) Connect high-current input and output
components with short and wide connections. The
high-current input loop goes from the positive
terminal of the input capacitor to the inductor and
the SW pin. The high-current output loop is from
the positive terminal of the input capacitor
through the inductor, rectifier diode, and positive
terminal of the output capacitors, reconnecting
between the output capacitor and input capacitor
ground terminals. Avoid using vias in the highcurrent paths. If vias are unavoidable, use
multiple vias in parallel to reduce resistance and
inductance.
3)
7) For the good thermal dissipation, PAM2842
has a heat dissipate pad in the bottom side, it
should be soldered to PCB surface. As the copper
area cannot be large in the component side, we
can use multiple vias connecting to other side of
the PCB.
8) R e f e r t o t h e e x a m p l e o f a PA M 2 8 4 2
Evaluation board layout below.
Create a ground island (PGND) consisting of
TSSOP-20 BOOST
QFN6x6-40 BOOST
PCB Layout Example
Power Analog Microelectronics , Inc
www.poweranalog.com
09/2008 Rev 1.1
14
PAM2842
High Power LED Driver
Ordering Information
PAM2842 X X X
Shipping
Number of Pin
Package Type
Part Number
Package
Shipping
PAM2842RGR
TSSOP-20
1,000 units/Tape & Reel
PAM2842TJR
QFN6X6-40
1,000 units/Tape & Reel
Power Analog Microelectronics , Inc
www.poweranalog.com
09/2008 Rev 1.1
15
PAM2842
High Power LED Driver
Outline Dimensions
TSSOP-20
SYMBOL
MIN.
NOM.
MAX.
SYMBOL
MIN.
NOM.
MAX.
A
-
-
1.20
b
0.19
-
0.30
A1
0.025
-
0.100
b1
0.19
0.22
0.25
A2
0.80
0.90
1.05
c
0.09
-
0.20
D
6.4
6.5
6.6
c1
0.09
-
0.16
E1
4.3
4.4
4.5
θ
0º
-
8º
E
6.2
6.4
6.6
L1
1.0 REF
L
0.45
0.60
0.75
e
0.65 BSC
R
0.09
-
-
N
20
R1
0.09
-
-
Power Analog Microelectronics , Inc
www.poweranalog.com
09/2008 Rev 1.1
16
PAM2842
High Power LED Driver
Outline Dimensions
QFN 6X6 -40
QFN
Unit: millimeter
Power Analog Microelectronics , Inc
www.poweranalog.com
09/2008 Rev 1.1
17