PAM2810ENG [PAM]
4-Channel Programmable LED Current Sink; 4通道可编程LED电流吸收
| 型号： | PAM2810ENG |
| 厂家： | 
POWER ANALOG MICOELECTRONICS |
| 描述： | 4-Channel Programmable LED Current Sink |
| 文件： | 总10页 (文件大小：160K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PAM2810
4-Channel Programmable LED Current Sink
Features
Description
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Cost Effective LED Driver
The PAM2810 provides 4 regulated current sinks,
capable of sinking up to 40mA current to
accommodate 4 white LEDs. It requires no charge
pump, has no noise and EMI, and significantly
improves the efficiency in Li bettery range.
Support up to 4 White LEDs
Output Current up to 40mA per LED
Low Dropout Voltage
Ultra Low Quiescent Supply Current:
65μA (typ)
No Noise and EMI
Shutdown Current Less than 1μA
Over Temperature Protection
Small Packages : SOT23-8 and DFN
2mmx2mm
LED brightness can be controlled by PWM
techniques. The constant current sink is set with
an external sense resistor.
Alternatively, a PWM signal applied to the EN pin
can vary the anticipated brightness of the LED.
The device is in shut down mode when the EN
input is logic low.
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Pb-free Package
Applications
The PAM2810 is available in SOT23-8 and DFN
2mmX2mm Packages.
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White LED for LCD Display Backlights
White LED Keypad Backlights
1-Cell Li-Ion Battery-operated Equipment
Including PDAs, Hand-held PCs, Cellular
Phone
Typical Application Circuit
VIN
C1
0.1ꢀF
4
VIN
8
LED1
2
EN
7
LED2
PAM2810
6
5
LED3
1
ISET
LED4
GND
3
R1
6.2k
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2008 Rev 1.1
1
PAM2810
4-Channel Programmable LED Current Sink
Typical Application Circuit
VBAT
VIN
VIN
C1
0.1μF
C1
0.1μF
4
4
VIN
VIN
8
7
6
5
8
LED1
LED1
LED2
LED3
LED4
2
1
2
EN
EN
7
LED2
PAM2810
PAM2810
6
LED3
1
ISET
ISET
5
LED4
NC
GND
3
GND
3
R1
6.2k Ω
R1
6.2kΩ
Block Diagram
VIN
VIN
LED1
LED2
LED3
LED4
CIN
0.1ꢀF
1.22V Ref
EN
Current
Setting
ISET
Current
Sinks
RSET
GND
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2008 Rev 1.1
2
PAM2810
4-Channel Programmable LED Current Sink
Pin Configuration
Top View
SOT23-8
Top View
DFN 2mmX2mm
VIN
GND
EN
1
2
3
4
8
7
6
5
LED1
LED2
ISET
1
2
3
4
LED1
LED2
LED3
LED4
8
7
6
5
EJ: Product Code
X: Internal Code
Y: Year
EN
GND
W: Week
LED3
LED4
VIN
ISET
Pin Number
Name
Description
DFN2x2
SOT23-8
1
2
3
4
5
6
7
8
4
3
2
1
5
6
7
8
VIN
GND
EN
Input Voltage
Ground
Enable, Allow PWM Brightness Control, Active High
LED Current Adjustment Pin
LED4 Cathode Terminal
ISET
LED4
LED3
LED2
LED1
LED3 Cathode Terminal
LED2 Cathode Terminal
LED1 Cathode Terminal
Power Analog Microelectronics,Inc
www.poweranalog.com
07/2008 Rev 1.1
3
PAM2810
4-Channel Programmable LED Current Sink
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 Range............................-0.3V to 6V
PWM Pin voltage...............-0.3V to (VIN+0.3V)/6V
Maximum Junction Temperature..................150°C
Operation Junction Temperature.....-40°C to 125°C
Storage Temperature.....................-65°C to 150°C
Soldering Temperature.......................300°C,5sec
Recommended Operating Conditions
Input Voltage Range..........................2.7V to 5.5V
Operation Temperature Range.........-40°C to 85°C
Thermal Information
Parameter
Symbol
Package
SOT23-8
DFN
Maximum
250
Unit
Thermal Resistance
(Junction to Ambient)
θJA
102
ºC/W
SOT23-8
DFN
130
Thermal Resistance
(Junction to Case)
θJC
20
Electrical Characteristic
TA=25°C, VIN=3.6V, RSET=5.1kΩ, VLEDX=0.5V, unless otherwise noted.
PARAMETER
Input Voltage
Symbol
VIN
CONDITIONS
MIN
TYP MAX UNITS
Vf+VLED
（Note）
3.6
5.5
40
V
mA
%
Output Current
ILEDX
VDD=5V
Current Matching Between
Any Two Outputs
ILED-MATCH
5
Current Sink Dropout
ISET PIN Voltage
VDROPOUT
Rset=3kΩ,ILEDX=40mA
0.25
V
V
VSET
1.22
100
Output Current to Current Set
Ratio
ILEDX/ISET
Quiescent Supply Current
Shutdown Supply Current
EN Input Logic High
EN Input Logic Low
IQ
Rset=10MΩ,with no loads
EN=logic low
65
80
1
μA
μA
V
ISHDN
VHI
0.1
1.4
VLO
0.4
1
V
V(EN) = 1.5V
V(EN) = 0V
0.1
0.1
μA
μA
EN Pin Current
IEN
1
Note: Vf: LED forward voltage; VLED: voltage of LEDx pins.
Power Analog Microelectronics,Inc
www.poweranalog.com
07/2008 Rev 1.1
4
PAM2810
4-Channel Programmable LED Current Sink
Typical Performance Characteristics
TA=25°C, VIN=3.6V, RSET=5.1kΩ, VLEDX=0.5V, unless otherwise noted.
LED Current VS LED Pin Voltage
LED Curent VS Input Voltage
45
40
35
30
25
20
15
10
5
45
40
35
30
25
20
15
10
5
R=12.7KΩ
R=4.3KΩ
R=6.2KΩ
R=3.2KΩ
R=12.7KΩ
R=4.3KΩ
R=6.2KΩ
R=3.2KΩ
0
0
0
0.3
0.6
0.9
1.2
1.5
3
0
0
3.5
4
4.5
5
5.5
Input Voltage(V)
LED Pin Voltage(V)
VIset VS Input Voltage
LED Current VS Rset
50
45
40
35
30
25
20
15
10
5
1.2135
1.2125
1.2115
1.2105
1.2095
1.2085
1.2075
0
3
3.5
4
4.5
5
5.5
5
10
15
20
Input Voltage(V)
Rset(kΩ)
LED Current vs PWM Duty Cycle
Efficiency VS Input Voltage
100
90
80
70
60
50
40
30
20
10
0
30
25
20
15
10
5
Rset=6.2k
0
3
3.25
3.5
3.75
4
4.25
4.5
20
40
60
80
100
Input Voltage(V)
PWM Duty Cycle (%)
Power Analog Microelectronics,Inc
www.poweranalog.com
07/2008 Rev 1.1
5
PAM2810
4-Channel Programmable LED Current Sink
Application Information
The PAM2810 is a 4-channel programmable
white-LED driver. The matched current regulators
each have a 100:1 ratio between the LEDx
outputs and the ISET current. The PAM2810 is
capable of supplying 40mA per channel with the
proper selection of the external RSET resistor,
with a total of 160mA output current available.
LED brightness control of PAM2810 can be
achieved with a PWM signal.
Table 2. PWM Frequency and Duty cycle
Frequency
100Hz
Cycle
10ms
Duty-Cycle Request
0.5
>
100
5
>
100
1kHz
1ms
10
>
100
2 kHz
4 kHz
8 kHz
10 kHz
500ꢀs
250ꢀs
125ꢀs
100ꢀs
Output Current Capability
20
>
100
The PAM2810 is capable of providing up to 40mA
per LED under an input voltage of 2.7V to 5.5V.
An external resistor is used to set the output
current, as approximated with the following
equation:
40
>
100
50
>
100
RSET=100 *(1.22V / ILEDX
)
In order that the output currents could be
regulated properly, the LEDx pin voltage(VLEDX
must be larger than the dropout voltage of the
current sink(VDROPOUT). To ensure the desired
)
The maximum PWM frequency can be selected
according to the table above.
current is obtained, apply the following equation
to determine the minimum input voltage:
If the PWM frequency is much less than 100Hz,
flickering may be seen in the LEDs. For the
PAM2810, zero duty cycle will turn off the LEDs
and a 50% duty cycle will result in an average
ILED being half of the programmed LED current.
For example, if RSET is set to program 20mA, a
50% duty cycle will result in an average ILED of
10mA. RSET should be chosen not to exceed the
maximum current capability of the device.
VIN - VDIODE = VLEDX ≥ VDROPOUT
VDIODE is the diode forward voltage, and some
typical value of VDROPOUT can be found from the
following table.
Table 1. ILED, RSET and VDROPOUT
ILED
RSET
12.7kΩ
6.2kΩ
4.3kΩ
3.2kΩ
VDR OPOUT
40mV
Shutdown
10mA
20mA
30mA
40mA
When the EN pin is logic low, the PAM2810 will be
in shutdown mode. While disabled, the PAM2810
typically draws 0.1μA current form the power
supply. There is no internal pull-up or pull-down
on the EN pin.
80mV
120mV
150mV
Over Temperature Protection
PWM Brightness Control
T h e PA M 2 8 1 0 e q u i p s o v e r t e m p e r a t u r e
protection. When the junction temperature (TJ)
exceeds +150°C, the current source turns off
automatically. The device will turn on again after
the IC’s TJ cools down under +125°C. Operating
at absolute maximum temperature is not
recommended.
Brightness control can be realized by applying a
PWM signal to the EN pin. The constant current is
set by the external resistor selected using the
R S E T e q u a t i o n . T h e L E D b r i g h t n e s s i s
proportional to the duty cycle (D) of the PWM
signal. The PWM frequency (f) should be limited
to accommodate the start-up time (50μs) of the
device.
D * (1/f) > 50μs
Power Analog Microelectronics,Inc
www.poweranalog.com
07/2008 Rev 1.1
6
PAM2810
4-Channel Programmable LED Current Sink
Parallel LEDx Outputs for Increased Current
Drive
Connecting outputs in parallel does not affect
internal operation of the PAM2810 and has no
impact on the electrical characteristics.
Output pins LED1 to LED4 may be connected
together in any combination to sink higher current
through fewer LEDs. For example in Figure 1,
outputs LED1 and LED2 are connected together
to drive one LED while LED3 and LED4 are
connected together to drive a second LED.
If less than four LEDs connected, the left pin can
be floating or connected to GND, as shown in
Typical Application Circuit on page 2.Connecting
to GND is recommended. The current calculating
method is the same as the RSET equation
mentioned.
Power Dissipation
The maximum allowable power dissipation that
the package is capable of handling can be
determined as follows:
LED1
VIN
LED2
0.1μF
Cin
LED3
PDMAX = (TJMAX - TA) /θJA
LED4
EN
Where TJMAX is the maximum junction temperature,
TA is the ambient temperature, and θJA is the
junction-to-ambient thermal resistance of the
specified package. The DFN 2x2 package has a
θJA of 80°C/W and the SOT23-8 250°C/W. This
value of θJA is highly dependant upon the layout of
the PCB. The actual power dissipated by the
PAM2810 follows the equation:
GND
ISET
Rset
Figure 1. Two Parallel Connected LEDs
With this configuration, two parallel current sinks
of equal value both provide current to each LED.
If the current sink provides 10mA each, every LED
can be drived with 20mA and gets double
brightness. Other combinations of parallel
outputs can be implemented similarly, such as in
Figure 2.
PDISS=(VIN *IIN) - N(VDIODE * ILEDX
)
Where N equals the number of active outputs,
VDIODE is the LED forward voltage, and ILEDX is the
current supplied to the LEDx.
Input Capacitor Selection
The PAM2810 is designed to work under a stable
input voltage. To ensure the stability of input, it
may be necessary to add a small input capacitor
to help filter out any noise that probably appears
on the line. Surface-mount multi-layer ceramic
capacitors are recommended, which are small
and inexpensive. A capacitance of 0.1μF is
typically sufficient.
LED1
VIN
LED2
0.1μF
Cin
LED3
LED4
EN
GND
ISET
Rset
Figure 2. One Parallel Connected LED
Power Analog Microelectronics,Inc
www.poweranalog.com
07/2008 Rev 1.1
7
PAM2810
4-Channel Programmable LED Current Sink
Ordering Information
PAM2810 X X
Package Type
Pin Configuration
Pin Configuration
Package Type
A:
B:
A: SOT23-8
1: VIN
1: ISET
2: EN
G: DFN 2x2-8
2: GND
3: EN
3: GND
4: VIN
5: LED4
6: LED3
7: LED2
8: LED1
4: ISET
5: LED4
6: LED3
7: LED2
8: LED1
Part Number
Marking
EJXYW
EJXYW
Package
DFN 2x2-8
SOT23-8
Shipping
PAM2810AG
PAM2810BA
3,000 units/Tape & Reel
3,000 units/Tape & Reel
Please consult PAM sales office or authorized distributors for more details.
Power Analog Microelectronics,Inc
www.poweranalog.com
07/2008 Rev 1.1
8
PAM2810
4-Channel Programmable LED Current Sink
Outline Dimensions
SOT23-8
(TYP)
(REF.)
L1(REF.)
Dimensions In Millimet
Dimensions In Millimet
ers
ers
Symbol
Symbol
Min
Max
Min
Max
0.60
L
L1
θ
A
A1
A2
c
1.45 MAX
0.30
0.60 (REF)
0
1.10
0.10
1.30
10°
0°
b
0.38
0.12 (REF)
0.22
e
D
E
0.65 (REF)
0.33 (REF)
3.10
3.00
1.80
2.70
2.60
1.40
e1
E1
Power Analog Microelectronics,Inc
www.poweranalog.com
07/2008 Rev 1.1
9
PAM2810
4-Channel Programmable LED Current Sink
Outline Dimensions
DFN 2x2
D
B
INDEX AREA
4
(D/2 xE/2)
TOP VIEW
9
C
SEATING
PLANE
8
SIDE VIEW
0.08 C
e
Nxb
Pin#1 ID
4
INDEX AREA
(D/2 xE/2)
D BSC
E BSC
MIN
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
b
NOM
MAX
MIN
D2
BOTTOM VIEW
D2 NOM
MAX
MIN
COMMON DIMENSION
E2 NOM
MAX
SYMBOL
MIN
NOM
MAX
0.70
0.00
0.75
0.02
0.80
0.05
A
A1
MIN
Summary Table
L
NOM
MAX
Lead
Lead
Count
8
Body
Size
2X2
Pin #1 ID
R0.20
Pitch (e)
0.50
N
Unit: Millimeters
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2008 Rev 1.1
10
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