View PAM2810_4237358.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

4-Channel Programmable LED Current Sink
PAM2810
Features
n n n n n
Description
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. 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. The PAM2810 is available in SOT23-8 and DFN 2 mmX2mm Packages.
n n n n
n
Cost Effective LED Driver Support up to 4 White LEDs Output Current up to 40mA per LED Low Dropout Voltage Ultra Low Quiescent Supply Current: 65 A (typ) No Noise and EMI Shutdown Current Less than 1 A Over Temperature Protection Small Packages : SOT23-8 and DFN 2mmx2mm Pb-free Package
Applications
n White LED for LCD Display Backlights n White LED Keypad Backlights n 1-Cell Li-Ion Battery-operated Equipment Including PDAs, Hand-held PCs, Cellular Phone
Typical Application Circuit
VIN C1 0.1F 4 VIN 2 EN
LED1 8
1
LED2 7 PAM2810 LED3 6 LED4 5 GND 3
ISET
R1 6.2 k
Power Analog Microelectronics , Inc
www.poweranalog.com 08/2008 Rev 1.1
1
4-Channel Programmable LED Current Sink
PAM2810
Typical Application Circuit
V BAT VIN C1 0.1F 4 VIN 2 LED1 EN PAM2810 1 ISET LED4 GND R1 6.2k 3
R1 6.2k VIN C1 0.1F 4 VIN 2 LED1 EN PAM2810 1 ISET LED4 GND 3 LED2 LED3
8 7 6 5
8 7 6 5 NC
LED2 LED3
Block Diagram
VIN
VIN C IN 0.1 F
1.22V Ref
LED1 LED2 LED3 LED4
EN ISET
Current Setting Current Sinks
RSET
GND
Power Analog Microelectronics , Inc
www.poweranalog.com 08/2008 Rev 1.1
2
4-Channel Programmable LED Current Sink
PAM2810
Pin Configuration
Top View DFN 2mmX2mm Top View SOT23-8
VIN GND EN ISET
1 2 3 4
8 7 6 5
LED1 LED2 LED3 LED4
ISET EN GND VIN
1
EJXYW
8 7 6 5
LED1 LED2 LED3 LED4
2 3 4
EJ: Product Code X: Internal Code Y: Year W: Week
Pin Number DFN2x2 1 2 3 4 5 6 7 8 SOT23-8 4 3 2 1 5 6 7 8
Power Analog Microelectronics , Inc
www.poweranalog.com 07/2008 Rev 1.1
EJX YW
Name VIN GND EN ISET LED4 LED3 LED2 LED1
Description Input Voltage Ground Enable, Allow PWM Brightness Control, Active High LED Current Adjustment Pin LED4 Cathode Terminal LED3 Cathode Terminal LED2 Cathode Terminal LED1 Cathode Terminal
3
4-Channel Programmable LED Current Sink
PAM2810
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 Operation Junction Temperature.....-40C to 125 C PWM Pin voltage............... -0.3V to (VIN+0.3V)/6V Storage Temperature.....................-65 C to 150 C Maximum Junction Temperature..................150C Soldering Temperature....................... 300C,5sec
Recommended Operating Conditions
Input Voltage Range.......................... 2.7V to 5.5V Operation Temperature Range.........-40 C to 85 C
Thermal Information
Parameter Thermal Resistance (Junction to Ambient) Thermal Resistance (Junction to Case) Symbol Package SOT23-8 JA DFN SOT23-8 JC DFN 20 102 C/W 130 Maximum 250 Unit
Electrical Characteristic
T A=25C, V IN=3.6V, R SET=5.1k , V LEDX=0.5V, unless otherwise noted.
PARAMETER Input Voltage Output Current Current Matching Between Any Two Outputs Current Sink Dropout ISET PIN Voltage Output Current to Current Set Ratio Quiescent Supply Current Shutdown Supply Current EN Input Logic High EN Input Logic Low EN Pin Current Symbol V IN ILEDX ILED-MATCH VDROPOUT VSET ILEDX/ISET IQ ISHDN VHI VLO IEN V(EN) = 1.5V V(EN) = 0V 0.1 0.1 Rset=10M,with no loads EN=logic low 1.4 0.4 1 1 Rset=3k,ILEDX=40mA 1.22 100 65 0.1 80 1 A A V V A A VDD=5V CONDITIONS MIN Vf+V LED Note TYP 3.6 MAX 5.5 40 5 0.25 UNITS V mA % V V
Note: Vf: LED forward voltage; V LED: voltage of LEDx pins.
Power Analog Microelectronics , Inc
www.poweranalog.com 07/2008 Rev 1.1
4
4-Channel Programmable LED Current Sink
PAM2810
Typical Performance Characteristics
T A=25C, V IN=3.6V, R SET=5.1k , V LEDX=0.5V, unless otherwise noted.
LED Current VS LED Pin Voltage 45 40
LED Current (mA)
45 40 35 LED Curent VS Input Voltage
35 30 25 20 15 10 5 0 0 0.3 0.6 0.9 1.2 1.5 LED Pin Voltage(V)
R=12.7K R=4.3K R=6.2K R=3.2K
LED Curent(mA)
30 25 20 15 10 5 0 3 3.5 4 4.5 5 5.5 Input Voltage(V)
R=12.7K R=4.3K R=6.2K R=3.2K
VIset VS Input Voltage 1.2135 1.2125
LED Current VS Rset 50 45 40
LED Current(mA)
1.2115
Viset(V)
35 30 25 20 15 10 5 0
1.2105 1.2095 1.2085 1.2075 3 3.5 4 4.5 5 5.5 Input Voltage(V)
0
5
10 Rset(k)
15
20
Efficiency VS Input Voltage 100 90 80
Efficiency(%)
LED Current vs PWM Duty Cycle
30 25
LED Current (mA)
70 60 50 40 30 20 10 0 3
Rset=6.2k
20 15 10 5 0
3.25
3.5
3.75
4
4.25
4.5
0
20
40
60
80
100
Input Voltage(V)
PWM Duty Cycle (%)
Power Analog Microelectronics , Inc
www.poweranalog.com 07/2008 Rev 1.1
5
4-Channel Programmable LED Current Sink
PAM2810
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. Output Current Capability 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: R SET=100 *(1.22V / I LEDX ) In order that the output currents could be regulated properly, the LEDx pin voltage(V LEDX) must be larger than the dropout voltage of the current sink(V DROPOUT). To ensure the desired current is obtained, apply the following equation to determine the minimum input voltage: V IN - V DIODE = V LEDX V DROPOUT V DIODE is the diode forward voltage, and some typical value of V DROPOUT can be found from the following table. Table 1. I LED, R SET and V DROPOUT
ILED 10mA 20mA 30mA 40mA RSET 12.7k 6.2k 4.3k 3.2k VDR OPOUT 40mV 80mV 120mV 150mV
Table 2. PWM Frequency and Duty cycle
Frequency 100Hz 1kHz 2 kHz 4 kHz 8 kHz 10 kHz Cycle 10ms 1ms 500s 250s 125s 100s Duty-Cycle Request > > > > > >
0.5 100
5 100 10 100 20 100 40 100 50 100
The maximum PWM frequency can be selected according to the table above. 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. Shutdown When the EN pin is logic low, the PAM2810 will be in shutdown mode. While disabled, the PAM2810 typically draws 0.1 A current form the power supply. There is no internal pull-up or pull-down on the EN pin. Over Temperature Protection 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 (T J) exceeds +150C, the current source turns off automatically. The device will turn on again after the IC's T J cools down under +125C. Operating at absolute maximum temperature is not recommended.
PWM Brightness Control 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 RSET equation. The LED brightness is proportional to the duty cycle (D) of the PWM signal. The PWM frequency (f) should be limited to accommodate the start-up time (50 s) of the device. D * (1/f) > 50 s
Power Analog Microelectronics , Inc
www.poweranalog.com 07/2008 Rev 1.1
6
4-Channel Programmable LED Current Sink
Parallel LEDx Outputs for Increased Current Drive 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.
PAM2810
Connecting outputs in parallel does not affect internal operation of the PAM2810 and has no impact on the electrical characteristics. 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
VIN
Cin 0. 1F
LED1 LED2 LED3 LED4
The maximum allowable power dissipation that the package is capable of handling can be determined as follows: P DMAX = (T JMAX - T A) / JA Where T JMAX is the maximum junction temperature, T A is the ambient temperature, and JA is the junction-to-ambient thermal resistance of the specified package. The DFN 2x2 package has a JA of 80C/W and the SOT23-8 250C/W. This value of JA is highly dependant upon the layout of the PCB. The actual power dissipated by the PAM2810 follows the equation: P DISS=(V IN *I IN) - N(V DIODE * I LEDX) Where N equals the number of active outputs, V DIODE is the LED forward voltage, and I LEDX is the current supplied to the LEDx. Input Capacitor Selection
EN 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.
VIN
Cin 0.1F
LED1 LED2 LED3 LED4
EN GND
ISET
Rset
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 0.1 F is typically sufficient.
Figure 2. One Parallel Connected LED
Power Analog Microelectronics , Inc
www.poweranalog.com 07/2008 Rev 1.1
7
4-Channel Programmable LED Current Sink
PAM2810
Ordering Information
PAM2810 X X
Package Type Pin Configuration
Pin Configuration A: 1: VIN 2: GND 3: EN 4: ISET 5: LED4 6: LED3 7: LED2 8: LED1 B: 1: ISET 2: EN 3: GND 4: VIN 5: LED4 6: LED3 7: LED2 8: LED1 Package Type A: SOT23-8 G: DFN 2x2-8
Part Number PAM2810AG PAM2810BA
Marking EJXYW EJXYW
Package DFN 2x2-8 SOT23-8
Shipping 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
4-Channel Programmable LED Current Sink
PAM2810
Outline Dimensions
SOT23-8
(TYP)
(MAX)
0.20
(REF.)
(REF.)
L1 ( REF.)
Symbol A A1 A2 c D E E1
Dimensions In Millimet ers Min Max 1.45 MAX 0 0.10 1.10 1.30 0.12 (REF) 3.10 2.70 3.00 2.60 1.80 1.40
Symbol L L1 b e e1
Dimensions In Millimet ers Min Max 0.60 0.30 0.60 (REF) 10 0 0.38 0.22 0.65 (REF) 0.33 (REF)
Power Analog Microelectronics , Inc
www.poweranalog.com 07/2008 Rev 1.1
9
4-Channel Programmable LED Current Sink
PAM2810
Outline Dimensions
DFN 2x2
D B
A
4
INDEX AREA (D/2 xE/2)
9
TOP VIEW
E A
C
SEATING PLANE
8
0.08 C
SIDE VIEW
e
Nxb
Pin#1 ID
4 INDEX AREA (D/2 xE/2)
E2
A1
D2
BOTTOM VIEW
SYMBOL A A1
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
Lead Pitch (e) 0.50
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
NxK
Unit: Millimeters
Power Analog Microelectronics , Inc
www.poweranalog.com 08/2008 Rev 1.1
10
NxL

▲Up To Search▲

Price & Availability of PAM2810

	To Download PAM2810 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .