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EUP3651
4-Channel, 1X/1.5X Charge Pump White LED Driver
DESCRIPTION
The EUP3651 is a high efficiency charge pump white LED driver. It supports 4 white LEDs with regulated constant current for uniform intensity. The EUP3651 maintains the highest efficiency by utilizing a 1.5X fractional charge pump and low dropout current regulators. A low external parts count (two 1uF flying capacitors and two small 1uF capacitors at VIN and VOUT) makes the EUP3651 ideally suited for small battery-powered applications. The EN logic input is used to enable, disable, and set current with a 16-step linear scale.The LED current can be configured between 5mA and 25mA. If EN is kept low for more than 1.5ms, the EUP3651 enters shutdown mode. The EUP3651 is available in a 12-pin 3mm x 3mm TDFN package.
FEATURES
1X/1.5X Mode for Ultra-High Efficiency Up to 25mA Output Current for Each Channel 2.7V to 5.5V Input Voltage 1MHz Fixed Switching Frequency Single-Wire Serial Pulse Interface to Set LED Current with 16-step Linear scale Soft Start Function Built-In Short-Circuit Protection Built-in Thermal Protection IQ<1uA in Shutdown TDFN-12 Package RoHS Compliant and 100% Lead (Pb)-Free
APPLICATIONS
Mobile phone Small LCD Backlighting Programmable Current Sinks White Photo Flash for Digital Cameras
Typical Application Circuit
Figure 1.
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Block Diagram
Figure 2.
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Pin Configurations
Package Type Pin Configurations
TDFN-12
Pin Description
PIN 1 2 3 4 5 6 7 8 9 10 11 12 EP NAME LED4 EN C1P C1N VOUT C2P C2N VIN GND LED1 LED2 LED3 TAB LED4 cathode terminal Device enable (active high) and 1 wire control input Bucket capacitor 1, positive terminal Bucket capacitor 1, negative terminal Charge pump output, connect to LED anodes Bucket capacitor 2, positive terminal Bucket capacitor 2, negative terminal Charge pump input, connect to battery or supply Ground LED1 cathode terminal LED2 cathode terminal LED3 cathode terminal Connect to GND on the PCB DESCRIPTION
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Ordering Information
Order Number EUP3651JIR1 Package Type TDFN-12 Marking xxxxx P3651 Operating Temperature range -40 C to 85C
EUP3651 1/4
1/4
1/4
1/4 Lead Free Code 1: Lead Free 0: Lead Packing R: Tape & Reel Operating temperature range I: Industry Standard Package Type J: TDFN
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Absolute Maximum Ratings
Input Voltage (VIN) ----------------------------------------------------------- -0.3V to +6V EN/SET to GND Voltage (VEN/SET) ---------------------------------- -0.3V to VIN +0.3V Maximum DC Output Current (IOUT) ----------------------------------------------- 150mA Operating Junction Temperature Range (TJ) ------------------------------- -40C to +150C Maximum Soldering Temperature (at leads, 10 sec) ------------------------------300C
Operating Ratings
Maximum Power Dissipation (PD) ------------------------------------------------------- 2W Operating Temperature (c JA) --------------------------------------------------------- 50C/W
Electrical Characteristics
(Over recommended operating conditions unless specified otherwise) VIN = 3.6V, EN = High, TAMB = 25ae . EUP3651 Symbol Parameter Conditions Min Typ Max VIN Operating Voltage 3 5.5 IQ ISD ILED-ERR Quiescent Current Shutdown Current LED Current Accuracy 1X mode, no load 1.5X mode, no load VEN = 0V EN Falling Edges = 1 Any two channel mismatch 1X mode, IOUT = 100mA 1.5X mode, IOUT = 100mA 1.5X mode VOUT < 0.5V 0.75 22.5 -3 1.75 4 1 250 400 500 160 20 -1 1.6 0.4 10 0.5 0.5 1.5 500 1000 100 100 1 1.25 25 0.65 2 1 2.5 1 27.5 3 Units V mA mA A mA % MHz mA mV s J J A V V s s s ms s
ILED-LED-ERR LED Channel Matching ROUT FOSC ISC VHYS TDLY TSD THYS IEN VHI VLO TSETUP TLO THI TOFF TDATADLY Output Resistance (open loop) Charge Pump Frequency Output short Circuit Current Limit 1.5X to 1X Transition Hysteresis Transition Filter Delay Thermal Shutdown Thermal Hysteresis EN Input Leakage EN Logic High Level EN Logic Low Level EN setup from shutdown EN program low time EN program high time EN low time to shutdown EN Delay to DATA
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Typical Operating Characteristics Quiescent Current vs. Temperature
2.40
0.5
Shutdown Current vs. Temperature
Quiescent Current (mA)
2.20
Shutdown Current (uA)
0.4
0.3
2.00
0.2
1.80
0.1
1.60 -40 -20 0 20 40 ) 60 80 Temperature (J
0.0 -40 -20 0 20 40 ) 60 80 Temperature (J
Normalized LED Current vs. Temperature
1.20
1200
Frequency vs. Temperature
Normalized LED Current
1.10
Frequency (kHz)
1100
1.00
1000
0.90
900
0.80 -40 -20 0 20 40 ) 60 80 Temperature (J
800 -40 -20 0 20 40 Temperature (J ) 60 80
Quiescent Current vs. Input Voltage
2.50
Frequency vs. Input Voltage
1200
-40J
-40J
Quiescent Current (mA)
25J 85J
1100
Frequency (kHz)
2.00
25J 85J
1000
1.50
900
1.00
800
0.50 2.7 3.2 3.7 4.2 4.7 5.2
700 2.7 3 3.3 3.6 3.9
Input Voltage (V)
Input Voltage (V)
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Efficiency vs. Load Current
100
Efficiency vs. Input Voltage
90 85
90
80 Efficiency (%)
VIN=3.6V VIN=4V
Efficiency (%)
75 70 65 60
80
70
60
55 50
Load Currnet=40mA
50 20.00 30.00 40.00 50.00 60.00 70.00 80.00
3
3.2
3.4
3.6
3.8
4
4.2
Load Current (mA)
Input Voltage (V)
Efficiency vs. Input Voltage
90 85 80 Efficiency (%)
Efficiency (%) 90 85 80 75 70 65 60
Load Currnet=60mA
Efficiency vs. Input Voltage
75 70 65 60 55 50 3 3.2 3.4 3.6 3.8 4 4.2 Input Voltage (V)
55 50 3 3.2 3.4
Load Currnet=80mA
3.6
3.8
4
4.2
Input Voltage (V)
Enable Transient Response
Shutdown Timeout
EN
EN VOUT VLED
VOUT VLED
IIN
IIN
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40mA Load at VIN=3V 80mA Load at VIN=3V
VIN
VIN
VOUT
VOUT
VLED VLED
40mA Load at VIN=3.6V
80mA Load at VIN=3.6V
VIN
VIN VOUT
VOUT
VLED
VLED
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Basic Operation
At power-up, the EUP3651 starts operating in 1X mode where the output will be approximately equal to the input supply voltage (less any internal voltage losses). If the output voltage is sufficient to regulate all LED currents, the device remains in 1X operating mode. If the input voltage is insufficient or falls to a level where the regulated currents cannot be maintained, the device automatically switches into 1.5X mode (after a fixed delay time of about 500s). In 1.5X mode, the output voltage is approximately equal to 1.5 times the input supply voltage (less any internal voltage losses). If the device detects a sufficient input voltage is present to drive all LED currents in 1X mode, it will change automatically back to 1X mode. The EN Serial Pulses Interface The current of the four LED channels can be configured by the EN logic input. By pulsing this signal with a specific protocol, the internal registers can be written into and then configure LEDs with the desired current. The EN serial pulses timing diagram see Figure 3. The LED current vs. EN series pulses edges as the Figure 4. LED Current vs. Pulse Edges
25 20
LED Current (mA)
15
10
5
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
EN Pulse Falling Edges
Figure 4. LED Current vs. Single Wire Series Pulse Falling Edges Unused LED Channels For applications with 3 LEDs or less, unused LEDs can be disabled by connecting the LED pin directly to VOUT, as shown on Figure 5. If LED pin voltage is within 1V of VOUT, then the channel is switched off and a 8A test current is placed in the channel to sense when the channel moves below VOUT - 1V.
Figure 3. EN Timing Diagram The device requires a minimum 10us delay TSETUP to ensure the initialization of the internal logic at power-up. TLO and THI must be between within 500ns to 100us. Once the final rising edge of DATA1 pulses transfer completed, the user must wait for more than 500us before transferring another DATA2 pulse falling edge. To power-down the device, the EN input should be kept low for a duration TOFF of 1.5ms or more. To power-down the device, the EN input should be kept low for a duration TOFF of 1.5ms or more. When power-down, all registers data are lost and reset to default value.
Figure 5. 3 LEDs Application Protection Mode If an LED is disconnected, the output voltage VOUT automatically limits at about 5.8V. This is to prevent the output pin from exceeding its absolute maximum rating. If the die temperature exceeds 160C the driver will enter a thermal protection shutdown mode. When the device temperature drops by about 20C the device will resume normal operation. LED Selection LEDs with forward voltages (VF) ranging from 1.3V to 4V may be used with the EUP3651. Selecting LEDs with lower VF is recommended in order to improve the efficiency by keeping the driver in 1X mode longer as the battery voltage decreases. For example, if a white LED with a VF of 3.3V is selected over one with VF of 3.5V, the EUP3651 will stay in 1X mode for lower supply voltage of 0.2V. This helps improve the efficiency and extends battery life.
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External Component The driver requires two external 1F ceramic capacitors for decoupling input, output, and for the charge pump. Both capacitors type X5R and X7R are recommended for the LED driver application. In charge pump modes, the input current ripple is kept very low by design and an input bypass capacitor of 1F is sufficient. In 1X mode, the device operates in linear mode and does not introduce switching noise back onto the supply. Layout Consideration Due to the switching frequency and high transient current of EUP3651, careful consideration of PCB layout is necessary. The CIN should be connected as close to the IC as possible. The ground of CIN and COUT should be placed as close as possible. To achieve the best performance of EUP3651, minimize the distance between every two components and also minimize every connection length with a maximum trace width. Make sure each device connects to immediate ground plane. A copper area matching the TDFN exposed pad (TAB) must be connected to the ground plane underneath. The use of multiple via improves the package heat dissipation.
Applications Examples
I. Use the EUP3651 to drive four LEDs for one panel backlighting.
II. Use the EUP3651 to drive 3 LEDs for one panel backlighting. The unused channel should be connected to VOUT.
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Packaging Information
TDFN-12
SYMBOLS A A1 b E D D1 E1 e L
MILLIMETERS MIN. MAX. 0.70 0.80 0.00 0.05 0.18 0.30 2.90 3.10 2.90 3.10 2.40 1.70 0.45 0.30 0.50
INCHES MIN. 0.028 0.000 0.007 0.114 0.114 0.094 0.067 0.018 0.012 0.020 MAX. 0.031 0.002 0.012 0.122 0.122
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