RT9296GQW

RT9296 Synchronous Boost Converter with LDO Controller General Description Features The RT9296 is a synchronous boost converter, which is based on a fixed frequency pulse-width-modulation (PWM) controller using a synchronous rectifier to obtain maximum efficiency. The converter provides a power supply solution for products powered by a variety of batteries such as single cell, dual cell alkaline, NiMH and NiCd battery. At light load currents, the converter enters the power save mode to maintain a high efficiency over a wide load current range. z True Load Disconnection During Shutdown z Internal Synchronous Rectifier Up to 96% Efficiency Current Mode PWM Operation with Internal Compensation Low Start-Up Voltage Low Quiescent Current Internal Soft-Start Control Linear Controller Low EMI Converter (Anti-Ringing) Power Save Mode for Improved Efficiency at Light Load Current Over-Current Protection Short Circuit Protection Over Temperature Protection Over Voltage Protection Small 10-Lead WDFN Package RoHS Compliant and Halogen Free The output voltage can be programmed by an external resistor divider, or be a fixed voltage. Moreover, the converter can be disabled to the minimize battery drain. During shutdown, the load is completely disconnected from the battery. The maximum peak current in the boost switch is limited to 2A for current limit. z z z z z z z z z z z z For the RT9296, a low-EMI (anti-ringing) mode is implemented (by trim option) to reduce ringing of the inductor phase pin when the converter enters the discontinuous conduction mode. Moreover, a linear controller is built-in in the chip for linear regulator application. Ordering Information z Applications z z z All One-Cell, Two-Cell and Three-Cell Alkaline, NiCd, NiMH and Single-Cell Li Batteries Hand-Held Devices WLED Flash Light ) Package Type QW : WDFN-10L 3x3 (W-Type) Lead Plating System G : Green (Halogen Free and Pb Free) Boost VOUT Default : Adjustable 33 : 3.3V 50 : 5.0V Note : Pin Configurations (TOP VIEW) EN VOUT FB/NC DRV GND 1 2 3 4 5 GND RT9296(- z 11 10 9 8 7 6 PGND LX PGOOD FBL VBAT WDFN-10L 3x3 Richtek products are : ` RoHS compliant and compatible with the current require- Marking Information ments of IPC/JEDEC J-STD-020. ` Suitable for use in SnPb or Pb-free soldering processes. DS9296-01 April 2011 For marking information, contact our sales representative directly or through a Richtek distributor located in your area. www.richtek.com 1 RT9296 Typical Application Circuit L 4.7µH V BAT C IN 10µF RT9296 VOUT 2 9 LX V OUT 6 VBAT R4 V OUT Chip Enable R1 DRV 4 8 1 5, Exposed Pad (11) Q1 C OUT 22µF LDO PGOOD R2 EN C LDO FBL 7 PGND 10 GND R3 Figure 1. Fixed Output Voltage Boost Converter with Linear Regulator L 4.7µH V BAT C IN 10µF VOUT 2 V OUT 6 VBAT R5 V OUT RT9296 9 LX Chip Enable R1 FB 3 8 1 5, Exposed Pad (11) PGOOD EN C OUT 22µF R3 R2 DRV 4 PGND 10 GND Q1 WLED FBL 7 R4 Figure 2. Adjustable Output Voltage Boost Converter with WLED Driver Functional Pin Description Pin No. Pin Name Pin Function 1 EN Chip Enable (Active High). 2 VOUT Boost Output. 3 FB / NC Feedback Pin / No Internal Connection. 4 DRV Driver of Linear Controller. 5 GND Ground. 6 VBAT Battery Supply Input. 7 FBL Feedback Input Linear Controller. 8 PGOOD Power Good Indicator. 9 LX Switching Node. Connect this Pin to an inductor. 10 PGND Power Ground. 11 (Exposed Pad) GND www.richtek.com 2 Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. DS9296-01 April 2011 RT9296 Function Block Diagram PGOOD Determine Higher Voltage Soft-Start Control EN V REF1 OCP, OTP, OVP V OUT EA VBAT VOUT Logic Control Back Gate Control UGATE LX PWM LGATE Current Sense GND PGND DRV Internal Compensation V REF2 + - FBL Figure 3. Fixed Voltage Regulator PGOOD V REF1 FB Determine Higher Voltage Soft-Start Control EN OCP, OTP, OVP EA VBAT VOUT Logic Control UGATE Back Gate Control LX PWM LGATE Current Sense GND PGND DRV Internal Compensation V REF2 + - FBL Figure 4. Adjustable Voltage Regulator DS9296-01 April 2011 www.richtek.com 3 RT9296 Absolute Maximum Ratings z z z z z z z z z z z z (Note 1) Supply Input Voltage, VBAT ---------------------------------------------------------------------------------------------Boost Output Voltage, VOUT -------------------------------------------------------------------------------------------Switch Output Voltage, LX ---------------------------------------------------------------------------------------------Digital Input Voltage, EN, FBL ----------------------------------------------------------------------------------------Digital Output Voltage, DRV, PGOOD -------------------------------------------------------------------------------Others Pin ------------------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C WDFN-10L 3x3 ------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) WDFN-10L 3x3, θJA ------------------------------------------------------------------------------------------------------WDFN-10L 3x3, θJC ------------------------------------------------------------------------------------------------------Junction Temperature Range -------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Mode) ---------------------------------------------------------------------------------------------MM (Machine Mode) ------------------------------------------------------------------------------------------------------ Recommended Operating Conditions z z z −0.3V to 6V −0.3V to 6.5V −0.3V to 6.5V −0.3V to 6V −0.3V to 6V −0.3V to 6V 1.429W 70°C/W 7.8°C/W 150°C 260°C −65°C to 150°C 2kV 200V (Note 4) Supply Input Voltage Range, VBAT ------------------------------------------------------------------------------------- 1.2V to 5V Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VBAT ≥ 2.5V or VBAT = VOUT + 0.7V, VEN = VBAT, CIN = 10μF, COUT = 22μF, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit -- 1.2 -- V 0.8 -- 5 V -- -- 5 V 0.49 0.5 0.51 -- 0.1 -- 0.49 0.5 0.51 V −3 -- +3 % DC/DC Stage Start-Up Input Voltage V BAT ILoad = 1mA Input Voltage Range After Start-Up V BAT Output Voltage Range V OUT EN Threshold Voltage V EN Rising Threshold Voltage V Hysteresis Voltage Feedback Reference Voltage V FB For Adjustable Output Voltage Output Voltage Accuracy ΔVOUT For Fixed Output Voltage Switching Frequency fSW -- 1.2 -- MHz Maximum Duty Cycle DMAX -- 90 -- % Non-Switching Quiescent Current IQ,NS No Switching -- 100 -- μA Shutdown Current ISHDN V EN = 0, VBAT = 1.2V -- 10 -- μA To be continued www.richtek.com 4 DS9296-01 April 2011 RT9296 Parameter Symbol Test Conditions Min Typ Max Unit Protection Over-Temperature Protection T OTP -- 170 -- °C Over-Temperature Hysteresis T OTP_Hys -- 40 -- °C Over-Current Protection IOCP 1.6 2 2.4 A Over-Voltage Protection V OVP 5.5 -- 6.5 V V OUT = 3.3V Power MOSFET N-MOSFET ON-Resistance RDS(ON)_N V OUT = 3.3V -- 260 -- mΩ P-MOSFET ON-Resistance RDS(ON)_P V OUT = 3.3V -- 290 -- mΩ 0.19 0.2 0.21 V -- 2 -- kΩ Linear Controller FBL Reference Voltage V FBL Output Impedance of Linear Controller RON_LBO V LBI = 0V Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2. θJA is measured in the natural convection at TA = 25°C on a high effective four layers thermal conductivity test board of JEDEC 51-7 thermal measurement standard. The case point of θJC is on the expose pad for the WDFN package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. DS9296-01 April 2011 www.richtek.com 5 RT9296 Typical Operating Characteristics Efficiency vs. Load Current Efficiency vs. Load Current 100 100 90 90 80 VIN = 3V VIN = 2.4V VIN = 1.8V VIN = 1.2V VIN = 0.9V 70 60 50 Efficiency (%) Efficiency (%) 80 40 30 20 VIN = 4.2V VIN = 3.6V VIN = 3V VIN = 2.4V VIN = 1.8V 70 60 50 40 30 20 10 10 VOUT = 3.3V 0 0.001 0.01 0.1 VOUT = 5V 0 0.001 1 0.01 Load Current (A) Efficiency vs. Input Voltage 100 90 90 60 Efficiency (%) Efficiency (%) 80 IOUT = 100mA IOUT = 10mA 70 IOUT = 200mA 50 40 30 IOUT = 10mA 70 IOUT = 100mA 60 50 40 30 20 20 10 10 VOUT = 5V VOUT= 3.3V 0 0 0.9 1.4 1.9 2.4 2.9 0.9 3.4 1.4 Output Voltage vs. Load Current 2.9 3.4 3.9 4.4 4.9 Output Voltage vs. Load Current 3.35 5.0 Output Voltage (V) 3.30 VIN = 3V VIN = 2.4V VIN = 1.8V VIN = 1.2V VIN = 0.9V 3.25 3.20 3.15 3.10 4.9 VIN = 4.2V VIN = 3.6V VIN = 3V VIN = 2.4V VIN = 1.8V VIN = 1.2V 4.8 4.7 4.6 3.05 0.01 0.1 Load Current (A) www.richtek.com 6 2.4 5.1 3.40 VOUT = 3.3V 3.00 0.001 1.9 Input Voltage (V) Input Voltage (V) Output Voltage (V) 1 Efficiency vs. Input Voltage 100 80 0.1 Load Current (A) 1 VOUT = 5V 4.5 0.001 0.01 0.1 1 Load Current (A) DS9296-01 April 2011 RT9296 Switching Frequency vs. Temperature 1300 5.5 1250 Switching Frequency (kHz) Output Voltage (V) Output Voltage vs. Input Voltage 6.0 5.0 IOUT= 10mA IOUT= 100mA 4.5 4.0 3.5 3.0 2.5 1200 1150 1100 1050 1000 950 VOUT = 5V VIN = 3.6V, VOUT = 5V 900 2.0 0.9 1.4 1.9 2.4 2.9 3.4 3.9 4.4 -50 4.9 -25 0 25 0.54 0.24 0.53 0.52 0.51 0.50 0.49 0.48 0.47 0.46 VIN = 3.6V, VOUT = 5V 25 50 0.22 0.21 0.20 0.19 0.18 0.17 0.16 75 100 0 25 50 75 100 125 CCM Switching VIN (2V/Div) VIN (2V/Div) VOUT (20mV/Div) VOUT (50mV/Div) ILX (200mA/Div) VLX (5V/Div) DS9296-01 April 2011 -25 Temperature (°C) DCM Switching VBAT = 3.6V, VOUT = 5V, ILOAD = 20mA VIN = 3.6V, VOUT = 5V -50 125 Temperature (°C) Time (1μs/Div) 125 0.23 0.15 0.45 0 100 FBL Reference Voltage vs Temperature 0.25 FBL Reference Voltage (V) FB Reference Voltage (V) FB Reference Voltage vs. Temperature 0.55 -25 75 Temperature (°C) Input Voltage (V) -50 50 ILX (500mA/Div) VBAT = 3.6V, VOUT = 5V, ILOAD = 200mA Time (250ns/Div) www.richtek.com 7 RT9296 Line Transient Response Load Transient Response VIN (2V/Div) VIN (2V/Div) VOUT (100mV/Div) VOUT (100mV/Div) IOUT (200mA/Div) IOUT (200mA/Div) VBAT = 3.6V, VOUT = 5V, ILOAD = 100mA to 200mA Time (500μs/Div) www.richtek.com 8 VBAT = 3V to 3.6V, VOUT = 5V, ILOAD = 200mA Time (500μs/Div) DS9296-01 April 2011 RT9296 Application Information The RT9296 integrates a high-efficiency synchronous stepup DC-DC converter and a linear regulator controller. To fully utilize its advantages, peripheral components should be appropriately selected. The following information provides detailed description of application. Inductor Selection For a better efficiency in high switching frequency converter, the inductor selection has to use a proper core material such as ferrite core to reduce the core loss and choose low ESR wire to reduce copper loss. The most important point is to prevent the core saturation when handling the maximum peak current. Using a shielded inductor can minimize radiated noise in sensitive applications. The maximum peak inductor current is the maximum input current plus the half of inductor ripple current. The calculated peak current has to be smaller than the current limitation in the electrical characteristics. A typical setting of the inductor ripple current is 20% to 40% of the maximum input current. If the selection is 40% 1 IPK = IIN(MAX) + IRIPPLE = 1.2 × IIN(MAX) 2 ⎡ IOUT(MAX) × VOUT ⎤ = 1.2 × ⎢ ⎥ ⎣ η × VIN(MIN) ⎦ The minimum inductance value is derived from the following equation : L= η × IIN(MIN)2 × [ VOUT − VIN(MIN) ] 0.4 × IOUT(MAX) × VOUT 2 × fSW Depending on the application, the recommended inductor value is between 2.2μH and 10μH. flows through the ESR, and the other is the capacitive ripple caused by charging and discharging. VRIPPLE = VRIPPLE(ESR) + VRIPPLE(C) ≅ IPEAK × RESR + IPEAK ⎡ VOUT − VIN ⎤ COUT ⎢⎣ VOUT × fSW ⎥⎦ Output Voltage Setting Referring to application circuit (Figure 2), the output voltage of the switching regulator (VOUT) can be set with below equation : R1 ⎞ ⎛ VOUT = ⎜ 1 + ⎟ × VFB ⎝ R2 ⎠ where VFB = 0.5V (typ.) Linear Regulator The RT9296 integrates a linear controller with an opendrain output. An external P-MOSFET and external feedback resistors are required for this application. The feedback voltage is set at 0.2V typically. For linear regulator application, the output voltage can be set by an external voltage resistive divider. For WLED driver application, the LED current can be set by an external feedback resistor. Thermal Considerations For continuous operation, do not exceed absolute maximum operation junction temperature. The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surroundings airflow and temperature difference between junction to ambient. The maximum power dissipation can be calculated by following formula : Input Capacitor Selection PD(MAX) = (TJ(MAX) − TA) / θJA For better input bypassing, low-ESR ceramic capacitors are recommended for performance. A 10μF input capacitor is sufficient for most applications. For a lower output power requirement application, this value can be decreased Where T J(MAX) is the maximum operation junction temperature, TA is the ambient temperature and the θJA is the junction to ambient thermal resistance. Output Capacitor Selection For lower output voltage ripple, low-ESR ceramic capacitors are recommended. The tantalum capacitors can be used as well, but the ESR is bigger than ceramic capacitor. The output voltage ripple consists of two components: one is the pulsating output ripple current DS9296-01 April 2011 For recommended operating conditions specification of RT9296, the maximum junction temperature is 125°C. The junction to ambient thermal resistance θJA is layout dependent. For WDFN-10L 3x3 packages, the thermal resistance θJA is 70°C/W on the standard JEDEC 51-7 four layers thermal test board. The maximum power dissipation at TA = 25°C can be calculated by following www.richtek.com 9 RT9296 PD(MAX) = (125°C − 25°C) / (70°C/W) = 1.429W for WDFN-10L 3x3 packages The maximum power dissipation depends on operating ambient temperature for fixed T J(MAX) and thermal resistance θJA. For RT9296 packages, the Figure 5 of derating curves allows the designer to see the effect of rising ambient temperature on the maximum power allowed. V BAT C OUT 10 PGND EN 1 L FB node copper 9 LX VOUT 2 R1 area should be 8 PGOOD FB/NC 3 V OUT minimized and 7 FBL DRV 4 R2 11 6 VBAT keep far away from GND 5 noise sources (LX pin) GND The GND and Exposed Pad should be connected to a strong ground plane for heat sinking and noise protection. Figure 6. PCB Layout Guide 1.6 Maximum Power Dissipation (W) C IN and C OUT should be placed close to the IC and connected to ground plane to reduce noise coupling. C IN GND formula : Four Layers PCB 1.4 1.2 WDFN-10L 3x3 1.0 0.8 0.6 0.4 0.2 0.0 0 25 50 75 100 125 Ambient Temperature (°C) Figure 5. Derating Curves for RT9296 Packages Layout Consideration For Best performance of RT9296, the following layout guidelines must be strictly followed. ` Input and Output capacitors should be placed close to the IC and connected to ground plane to reduce noise coupling. ` The GND and Exposed Pad should be connected to a strong ground plane for heat sinking and noise protection. ` Keep the main current traces as possible as short and wide. ` Place the feedback components as close as possible to the IC and keep away from the noisy devices. www.richtek.com 10 DS9296-01 April 2011 RT9296 Outline Dimension D2 D L E E2 1 e SEE DETAIL A b 2 1 2 1 A A1 A3 DETAIL A Pin #1 ID and Tie Bar Mark Options Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.180 0.300 0.007 0.012 D 2.950 3.050 0.116 0.120 D2 2.300 2.650 0.091 0.104 E 2.950 3.050 0.116 0.120 E2 1.500 1.750 0.059 0.069 e L 0.500 0.350 0.020 0.450 0.014 0.018 W-Type 10L DFN 3x3 Package Richtek Technology Corporation Richtek Technology Corporation Headquarter Taipei Office (Marketing) 5F, No. 20, Taiyuen Street, Chupei City 5F, No. 95, Minchiuan Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Tel: (8862)86672399 Fax: (8862)86672377 Email: marketing@richtek.com Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek. DS9296-01 April 2011 www.richtek.com 11