芯美电子 EUP3618 Preliminary Charge Pump Flash LED Driver with Safety Timer DESCRIPTION FEATURES The EUP3618 is a high-current charge pump, optimized for driving Flash LEDs used in camera phone and other portable applications. It has two modes of operation which are pin selectable for either Flash or Torch. In Flash mode, the EUP3618 output can drive 500mA regulated current into an LED for a duration of 500ms or up to 700mA for a reduced duration. In Torch mode the EUP3618 regulates the output current to 40% of the Flash mode current setting and can remain enabled continuously. The EUP3618 operates in 2x mode while operating in Flash mode. In Torch mode it can operate in either 2x or 1x mode depending on the load current, LED forward voltage, and input voltage levels. Input Voltage Range — 2.7V to 5.25V Flash and Torch — Two Selectable Modes Up to 700mA Output Current — Flash Mode Torch Mode Set to 40% of Flash Current, Up to 280mA Output IQ < 1µA in Shutdown Time-Out Circuit Limits Flash Duration to 1 Second External Flash Control Pin for Synchronization to Camera Short-Circuit, Over-Voltage, and Over-Temperature Protection Internal Soft-Start Limits Inrush Current Independent Flash and Torch Control 3mm x 3mm TDFN-10 Package RoHS Compliant and 100% Lead (Pb)-Free APPLICATIONS Camera Flash in Mobile Phones Flash for Digital Still Cameras White LED Torch Typical Application Circuit Figure 1. DS3618 Ver0.1 Mar. 2008 1 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 Preliminary EUP3618 Pin Configurations Package Type Pin Configurations TDFN-10 Pin Description PIN NAME 1 VIN Input voltage 2 C2N Negative terminal of bucket capacitor 2 3 GND Ground— connect to ground plane using multiple vias 4 C1N 5 FLASH 6 ISET 7 CTRL 8 C1P Negative terminal of bucket capacitor 1 Flash mode enable pin— puts the device in active flash mode when high and also overrides CTRL. Current-setting reference pin — connect to the LED cathode and the current setting resistor. Control input bit — used to enable and set the output current in Torch mode when high. Positive terminal of bucket capacitor 1 9 VOUT Output pin — connect to the LED anode 10 C2P Positive terminal of bucket capacitor 2 DS3618 Ver0.1 Mar. 2008 DESCRIPTION 2 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 Preliminary EUP3618 Ordering Information Order Number Package Type Marking Operating Temperature Range EUP3618JIR1 TDFN-10 xxxxx P3618 -40 °C to 85°C EUP3618 □ □ □ □ Lead Free Code 1: Lead Free 0: Lead Packing R: Tape & Reel Operating temperature range I: Industry Standard Package Type J: TDFN Block Diagram Figure 2. DS3618 Ver0.1 Mar. 2008 3 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 EUP3618 Preliminary Absolute Maximum Ratings VIN(V),VOUT(V) -------------------------------------------------- -0.3V to 6.5V C1P,C2P(V) ----------------------------------------------------- -0.3V to (VOUT+0.3V) Pin Voltage-All Other Pins (V)-------------------------------------- -0.3V to (VIN+0.3V) Junction Temperature --------------------------------------------------- -40°C to 150°C Lead Temperature ------------------------------------------------------------------------ 260°C Storage Temperature --------------------------------------------------------- -60°C to 150°C Operating Ratings Operating Temperature ---------------------------------------------------------- -40°C to 85°C Thermal Resistance θJA (TDFN-10) ----------------------------------------------- 55°C/W Electrical Characteristics Unless otherwise specified: TA = 25°C for TYP; C1=C2 = COUT = 1uF (ESR < 0.1Ω); CIN = 10uF; VIN = 3.0V to 5.5V; VOUT = 3.1V to 4.2V; RSET = 0.5Ω (0.1%). EUP3618 Symbol Parameter Conditions Units Min Typ. Max VIN Input Voltage 2.7 5.5 V Flash HIGH, RSET=0.5Ω 3.3V < VIN < 4.2V 3.1V < VOUT < 4.2V IOUT VSET VSET(P-P) IQ Output Current ISET Reference Voltage ISET Ripple Voltage 212 280 mV Flash LOW, CTRL High， RSET=0.5Ω 3.3V < VIN < 4.2V 3.1V < VOUT < 4.2V 106 IOUT=500mA 20 IOUT=200mA 10 VIN < 3V, Flash or CTRL HIGH 5 mV 6 mA Quiescent Current VIN > 3V, Flash or CTRL High Output Resistance (open loop) tFLASH Flash Mode Pulse Duration tSTART Flash Mode Start-Up time tSAFE Flash Mode Safety Timer FOSC Charge Pump Frequency Flash and CTRL LOW 1X mode, IOUT = 200mA 2X mode, IOUT =200mA 3.3V < VIN < 4.2V, VOUT > 3.1V, IOUT =500mA Device Enabled Output short circuit Current Limit VOUT < 0.5V DS3618 Ver0.1 Mar. 2008 mA Flash LOW, CTRL High， RSET=0.5Ω 3.3V < VIN < 4.2V 3.1V < VOUT < 4.2V Flash HIGH, RSET=0.5Ω 3.3V < VIN < 4.2V 3.1V < VOUT < 4.2V ROUT ISC 560 3 4.5 0.1 0.8 3 1 uA Ω 500 ms 1 ms 0.8 1 1.2 s 0.8 1 1.2 MHz 650 4 联系电话：１５９９９６４４５７９ ８３１５１７１５ mA 芯美电子 EUP3618 Preliminary Electrical Characteristics (continued) Unless otherwise specified: TA = 25°C for TYP; C1=C2 = COUT = 1uF (ESR < 0.1Ω); CIN = 10uF; VIN = 3.0V to 5.5V; VOUT = 3.1V to 4.2V; RSET = 0.5Ω (0.1%). EUP3618 Symbol Parameter Conditions Units Typ. Max Min ILMT Input Current Limit 2X Mode, 3V < VIN < 4.2V 1.5 A VHI Logic High Level Flash, CTRL VLO Logic Low Level Flash, CTRL IIH Input Leakage Flash, CTRL -1 1 IIL Input Leakage Flash, CTRL -1 1 TSD Thermal Shutdown 150 ℃ THYS Thermal Hysteresis 20 ℃ DS3618 Ver0.1 Mar. 2008 1.6 0.4 5 联系电话：１５９９９６４４５７９ ８３１５１７１５ V µA 芯美电子 EUP3618 Preliminary Typical Operating Characteristics Flash Current 100ms,RISET=500mΩ 515 510 510 LED Current (mA) LED Current (mA) Flash Current 10ms,RISET=500mΩ 515 505 500 495 490 505 500 495 490 485 485 3.3 3.45 3.6 3.75 3.9 4.05 4.2 3.3 3.45 Flash Current 500ms,RISET=500mΩ 3.75 3.9 4.05 250 525 220 LED Current (mA) 520 515 510 505 190 160 130 500 3.3 3.45 3.6 3.75 3.9 4.05 100 4.2 5.25 VIN (V) 4.8 4.35 3.9 3.45 VIN (V) Torch Current, RISET=500mΩ 530 525 LED Current (mA) 4.2 Torch Current, RISET=500mΩ 530 LED Current (mA) 3.6 VIN (V) VIN (V) 520 515 VIN=3.3V 510 VIN=3.7V 505 VIN=4.2V 500 0 100 200 300 400 500 Pulse Duration (ms) DS3618 Ver0.1 Mar. 2008 6 联系电话：１５９９９６４４５７９ ８３１５１７１５ 3 芯美电子 Preliminary EUP3618 Typical Operating Characteristics (continued) Flash Mode Ripple, RISET=500mΩ Start-Up Flash, 500mA Safety Timer Shut-Off Torch 1X Mode Ripple, RISET=500mΩ Torch 2X Mode Ripple, RISET=500mΩ DS3618 Ver0.1 Mar. 2008 Short Circuit Current Limiting,VIN=5.25V,VOUT=0V 7 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 Preliminary Flash Mode Safety Timer The EUP3618 provides a time-out protection function when in flash mode. The output is disabled if the FLASH pin is held high for longer than 1 second to protect the LED. Once this time-out has occurred, the output will stay disabled until the FLASH pin has been pulled low and then re-enabled. Applications Information General Operation The EUP3618 is a powerful dual-mode charge pump designed to drive a high-intensity white LED. A constant current Torch mode or a pulsed current with higher intensity is used for camera flash. The device operates in 2x mode while operating in flash mode. In Torch mode it can operate in either 2x or 1x mode depending on the load current, load voltage, and input voltage levels. In flash mode the EUP3618 output can drive 500mA at 4.25V into an LED for a duration of 500ms under all temperature and input conditions. The FLASH pin is used to trigger this mode (active high). In Torch mode the EUP3618 regulates the output current to 40% of the flash mode current setting, when the CTRL pin is pulled high and the FLASH pin is low. Flash mode has priority over Torch mode, i.e., the FLASH pin triggers flash mode regardless of the state of the CTRL pin. Output current is regulated by attaching the ISET pin to the cathode(s) of the LED package and a low resistance sense resistor (typically 0.5Ω). The ISET pin monitors the voltage at the cathode and signals the charge pump to increase or decrease the output current until the ISET voltage reaches the programmed setting. The resistor value is chosen to set the current through the LED based on this reference voltage. The resistor can be chosen to set either the flash mode current or Torch mode current, but it should not be less than 0.35Ω due to output current limitations of the device. Torch Mode Torch mode is enabled by setting the CTRL pin high and keeping the FLASH pin low. When in Torch mode, the EUP3618 can maintain a constant current indefinitely to drive an LED or bank of LEDs. The ISET reference voltage is set to 100mV so that the output current is maintained at 200mA when a 0.5Ω resistor is used. Torch current is always 40% of flash current for any given value of RISET. In Torch mode, IOUT = 100mV/RISET. To maximize power efficiency, the EUP3618 has been designed to operate in 1x mode when conditions do not require the charge pump to be active. When first enabled the EUP3618 attempts to regulate the voltage on the ISET pin in 1x mode. If the voltage on the ISET pin cannot be maintained and this condition persists for longer than 500µs, then the charge pump will change to 2x mode operation. In a typical application, the EUP3618 will operate in 1x mode until the supply voltage decreases sufficiently that the voltage on the ISET pin can no longer be maintained. After a 500µs delay (included to prevent false transitions) the charge pump will convert to 2x mode. After the charge pump switches from 1x mode to 2x mode, the device remains in 2x mode until the part is turned off. If the part is re-enabled in Torch mode, it will begin operation in 1x mode and determine the appropriate mode of operation as previously described. Flash Mode Flash mode is enabled whenever the FLASH pin is pulled high and remains active until the FLASH pin is released. This mode has higher priority than Torch mode, so the state of the CTRL pin is overridden whenever the FLASH pin is activated. While in flash mode the reference voltage on the ISET pin is set to 250mV. The duration of the pulse is limited by the amount of power that can be dissipated in the EUP3618 before it exceeds the maximum operating temperature. If an output current less than the rated 500mA is desired, the duration of the pulse can increase proportionally. Extending flash mode beyond the 500ms pulse limit could adversely affect the long term reliability of the EUP3618. Flash duration must be derated at higher currents. For example, 700mA derates to a maximum of 350ms. In flash mode, IOUT = 250mV/RISET. Figure 1 shows maximum flash mode current for extended duration times. DS3618 Ver0.1 Mar. 2008 EUP3618 Protection Circuitry The EUP3618 provides several protection features to safeguard the device from catastrophic failures. These features include: Output Over-Voltage Protection (OVP) Over-Temperature Protection (OTP) Over-Current Protection (OCP) Short-Circuit Current Protection (SCCP) Output Over-Voltage Protection Output OVP prevents the EUP3618 from generating an output voltage that could damage other devices connected to it such as load LEDs and bypass capacitors. When the output voltage exceeds 5.8V, the OVP circuit disables the charge pump until the voltage decreases to a level within the acceptable range. This circuit allows the device to drive LEDs with high forward voltages at a reduced level without exceeding the output voltage limits specified for the device. 8 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 Preliminary EUP3618 Thermal Resistance Considerations The EUP3618 package is thermally efficient when the circuit board layout connects the thermal pad through multiple vias to the ground plane. The thermal resistance is rated at 50°C/W, and this rating is dependent on the connection between the thermal pad and the ground plane. The layout should keep the junction temperature below the OTP limit while operating the EUP3618 within the specified electrical conditions for IOUT and VISET. A poor layout may allow the junction temperature to reach the OTP limit while in flash or Torch mode. It is critical to maintain adequate ground plane around the device to maximize heat transfer and avoid over-temperature shutdown. Over-Temperature Protection The OTP circuit prevents the device from overheating and experiencing a catastrophic failure. When the junction temperature exceeds 150 ℃ the device is disabled. It remains disabled until the junction temperature drops below this threshold. Hysteresis is included to prevent toggling between modes. Over-Current Protection When the EUP3618 is in 2x mode, the input current will be approximately double the required output. When the steady-state load requires the maximum current available in 2x mode, the OCP circuit prevents the device from overheating from excessive power dissipation. This feature protects the device when in 1x mode. The current limit is set lower in the 1x mode due to lower current requirements. Short-Circuit Current Protection SCP is provided to limit the current that can be sourced when the output is shorted to ground. When a short circuit forces VOUT to drop below 2V, the SCP detects the condition and limits the output current. Resistor Selection The ISET resistor selection is critical in generating the correct current. The value can be chosen to set the Torch mode current or the flash mode current, and the two current settings are dependent on the same resistor. It is recommended that the resistor be selected to match the desired LED current for flash mode. This allows the designer to set the EUP3618’s maximum current and select the resistor package size necessary for the power dissipation required in flash mode. The typical application uses a 0.5Ω resistor to set a flash mode current of 500mA and Torch mode current of 200mA. A high precision resistor should be used to ensure the specified accuracy for LED current. To avoid malfunction of the charge pump, it is recommended that the resistance seen at the ISET pin remain constant while the device is active (flash or Torch mode). Changing the resistance value or the load current while the device is active could cause instability. Capacitor Selection The EUP3618 is designed to use low-ESR ceramic capacitors for the input and output bypass capacitors as well as the charge pump bucket capacitors. Ideal performance is achieved when C1 is exactly equal to C2. It is recommended that X5R or X7R ceramic capacitors be used for best performance. DS3618 Ver0.1 Mar. 2008 9 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 EUP3618 Preliminary Packaging Information TDFN-10 SYMBOLS A A1 D1 D E1 E L b e D1 DS3618 Ver0.1 Mar. 2008 MILLIMETERS MIN. MAX. 0.70 0.80 0.00 0.05 2.50 2.90 3.10 1.70 2.90 3.10 0.30 0.50 0.18 0.30 0.50 2.40 INCHES MIN. 0.028 0.000 MAX. 0.031 0.002 0.098 0.114 0.122 0.067 0.114 0.012 0.007 0.122 0.020 0.012 0.020 0.094 10 联系电话：１５９９９６４４５７９ ８３１５１７１５