RT8239A RICHTEK | Alldatasheet
Document overview
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Technical content
Features
zzzzz 5.5V to 25V Input Voltage Range zzzzz 2V to 5.5V Output Voltage Range zzzzz No Current Sense Resistor Needed zzzzz 5V/3.3V Linear Regulators zzzzz 4700ppm/°°°°°C RDS(ON) Current Sensing zzzzz Internal Current Limit Soft-Start and Soft Discharge Output zzzzz Built In OVP/UVP/OCP zzzzz Selectable Operation Mode with Switcher Enable Control (RT8239A) zzzzz SECFB Input Maintains Charge Pump Voltage (RT8239B/C) zzzzz Power Good Indicator (RT8239B/C includes SECFB) zzzzz RoHS Compliant and Halogen Free
Applications
z 3- and 4- Cell Li+ Battery-Powered Device RT8239A/B/C Package Type QW : WQFN-20L 3x3 (W-Type) Lead Plating System G : Green (Halogen Free and Pb Free) Z : ECO (Ecological Element with Halogen Free and Pb free) Pin Function With A : ENM B : SECFB C : SECFB, Ultrasonic Mode
DS8239A/B/C-06 October 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Pin Configurations (TOP VIEW) RT8239B/CRT8239A WQFN-20L 3x3 BYP1 BOOT1 ENTRIP2 TON FB1 ENTRIP1 LDO3 LDO5 ENLDO ENM PGOOD BOOT2 PHASE2 PHASE1 UGATE1 LGATE1 FB2 VIN LGATE2 UGATE2 17181920 9876 GND 115 LDO3 LDO5 ENTRIP2 TON FB1 ENTRIP1 ENLDO SECFB PGOOD BOOT2 PHASE2 BYP1 BOOT1 PHASE1 UGATE1 LGATE1 FB2 VIN LGATE2 UGATE2 17181920 9876 GND 115 Marking Information JB=YM DNN JB YM DNN JB= : Product Code YMDNN : Date Code JB : Product Code YMDNN : Date Code RT8239A JC=YM DNN JC YM DNN JC : Product Code YMDNN : Date Code JC= : Product Code YMDNN : Date Code RT8239B JD=YM DNN JD YM DNN JD : Product Code YMDNN : Date Code JD= : Product Code YMDNN : Date Code RT8239C
©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Figure 1. RT8239A NB Main Supply Typical Application Circuit
©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Figure 2. RT8239B/C NB Main Supply Typical Application Circuit
DS8239A/B/C-06 October 2012 www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Pin No. Pin Name Pin Function 1 FB1 SMPS1 Feedback Input. Connect FB1 to a resistive voltage divider from SMPS1 output to GND for adjustable output from 2V to 5.5V.
2 ENTRIP1
Channel 1 Enable and Current Limit Setting Input. Connect resistor to GND to set the threshold for Channel 1 synchronous R DS(ON) sense. The GND-PHASE1 current limit threshold is 1/10th the voltage seen at ENTRIP1 over a 0.5V to 3V range. There is an internal 10 μA current source from LDO5 to ENTRIP1. Leave ENTRIP1 floating or drive it above 4.5V to shut down channel 1. 3 TON ON-Time/Frequency Adjustment Input. Connect to GND with 56k Ω to 100kΩ.
4 ENTRIP2
Channel 2 Enable and Current Limit Setting Input. Connect resistor to GND to set the threshold for Channel 2 synchronous R DS(ON) sense. The GND-PHASE2 current limit threshold is 1/10th the voltage seen at ENTRIP2 over a 0.5V to 3V range. There is an internal 10 μA current source from LDO5 to ENTRIP2. Leave ENTRIP2 floating or drive it above 4.5V to shut down channel 2. 5 FB2 SMPS2 Feedback Input. Connect FB2 to a resistive voltage divider from SMPS2 output to GND for adjustable output from 2V to 5.5V. Power Good Output for Channel 1 and Channel 2 (RT8239A).
6 PGOOD
Power Good Output for Channel 1, Channel 2 and SECFB (RT8239B/C). 7 BOOT2 Boost Flying Capacitor Connection for SMPS2. Connect to an external capacitor according to the typical application circuits. 8 UGATE2 Upper Gate Driver Output for SMPS2. UGATE2 swings between PHASE2 and BOOT2. 9 PHASE2 Switch Node for SMPS2. PHASE2 is the internal lower supply rail for the UGATE2 high side gate driver. PHASE2 is also the current sense input for the SMPS2. 10 LGATE2 Lower Gate Drive Output for SMSP2. LGATE2 swings between GND and LDO5. 11 VIN Supply Input for LDO5.
12 ENLDO
Master Enable Input. LDO5/LDO3 is enabled if it is within logic high level and disabled if it is less than the logic low level. Leave ENLDO floating to default enable LDO5/LDO3. ENM (RT8239A) Mode Selection with Enable Input. Pull up to LDO5 (Ultrasonic mode) or LDO3 (DEM) to turn on both switch Channels. Short to GND for shutdown.
13 SECFB
(RT8239B/C) Change Pump Feedback Pin. The SECFB is used to monitor the optional external charge pump. Connect a resistive divider from the change pump output to GND to detect the output. If SECFB drops below its feedback threshold, an ultrasonic pulse occurs to refresh the charge pump driven by LGATE1 or LGATE2. If SECFB drops below its UV threshold, the switcher channels stop working and enter into discharge-mode. Pull up to LDO5 or LDO3 to disable SECFB UVP function.
14 LDO5
5V Linear Regulator Output. LDO5 is the supply voltage for the low side MOSFET driver and also the analog supply voltage for the device. Bypass a minimum 4.7μF ceramic capacitor to GND 15 LDO3 3.3V Linear Regulator Output. Bypass a minimum 4.7 μF ceramic capacitor to GND. 16 LGATE1 Lower Gate Driver Output for SMPS1. LGATE1 swings between GND and LDO5. 17 PHASE1 Switch Node SMPS1. PHASE1 is the internal lower supply rail for the UGATE1 high side gate driver. PHASE1 is also the current sense input for the SMPS1. Functional Pin Description
DS8239A/B/C-06 October 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Function Block Diagram Pin No. Pin Name Pin Function 18 UGATE1 Upper Gate Driver Output for SMPS1. UGATE1 swings between PHASE1 and BOOT1. 19 BOOT1 Boost Flying Capacitor Connection for SMPS1. Connect to an external capacitor according to the typical application circuits. 20 BYP1 Switch Over Source Voltage Input for LDO5. 21 (Exposed Pad) GND Analog Ground and Power Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. ENM (RT8239A) SECFB (RT8239B/C) SMPS2 PWM Buck Controller BOOT2 UGATE2 PHASE2 LGATE2 GND LDO5 FB2 ENTRIP2 PGOOD SMPS1 PWM Buck Controller BOOT1 UGATE1 PHASE1 LGATE1 LDO5 FB1 ENTRIP1 LDO5 REF Switch Over Threshold VIN LDO5 On TimeTON LDO3 LDO3 BYP1 Power-On Sequence Clear Fault LatchENLDO LDO5 10µA LDO5 10µA
DS8239A/B/C-06 October 2012 www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Recommended Operating Conditions (Note 4) Absolute Maximum Ratings (Note 1) z PHASEx to GND z UGATEx to PHASEx z LGATEx to GND z Power Dissipation, PD @ TA = 25°C z Package Thermal Resistance (Note 2) z ESD Susceptibility (Note 3) Parameter Symbol Test Conditions Min Typ Max Unit Input Supply Rising Threshold -- 5.1 5.5 VIN Power On Reset Falling Threshold 3.5 -- 4.5 V VIN Shutdown Current IVIN_SHDN V ENLDO = GND -- 20 40 VIN Standby Supply Current IVIN_SBY Both SMPS Off -- 250 350 μA Quiescent Power Consumption IQ Both SMPSs on, FBx = 2.1V, BYP1 = 5V, ENM = 3.3V (RT8239A) -- 5 7 mW SMPS Output and FB Voltage FBx, CCM Operation -- 2 -- FBx Regulation Voltage VFBx FBx, DEM Operation 1.98 2.006 2.03 V (VIN = 12V, VENLDO = 5V, VENTRIPx = 2V, VBYP1 = 5V, No Load on LDO5, LDO3, TA = 25°C, unless otherwise specified)
Electrical Characteristics
DS8239A/B/C-06 October 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Parameter Symbol Test Conditions Min Typ Max Unit Output Voltage Adjustable Range SMPS1, SMPS2 2 -- 5.5 SECFB Voltage VSECFB RT8239B 1.92 2 2.08 V On-Time VPHASE1 = 2V -- 256 -- On-Time Pulse Width tUGATEx VIN = 20V RTON = 56kΩ VPHASE2 = 2V -- 220 -- ns Minimum Off-Time tLGATEx V FBx = 1.8V -- -- 400 ns fSMPS1 SMPS1 Operating Frequency 200 -- 400 Frequency Range fSMPS2 SMPS2 Operating Frequency 233 -- 466 kHz Ultrasonic Mode Frequency fASM RT8239C, V PHASEx = 50mV 25 -- -- kHz Soft-Start Soft-Start Time tSSx Zero to 200mV Current Limit Threshold from ENTRIPx Enable -- 2 -- ms Current Sense Current Limit Current Source IENTRIPx V ENTRIPx = 0.9V 9.4 10 10.6 μA Temperature Coefficient of IENTRIPx On The Basis of 25°C -- 4700 -- ppm/°C Current Limit Adjustment Range VENTRIPx = IENTRIPx x RENTRIPx 0.5 -- 2.7 V Current Limit Threshold VENTRIPx GND − PHASEx, VENTRIPx = 2V 180 200 225 mV Zero-Current Threshold VZC GND − PHASEx, FBx = 2.1V -- 3 -- mV Internal Regulator and Reference VBYP1 = 0V, ILDO5 < 100mA 4.8 5 5.2 VBYP1 = 0V, ILDO5 < 100mA , 6.5V < VIN < 25V 4.75 -- 5.25 LDO5 Output Voltage VLDO5 VBYP1 = 0V, ILDO5 < 50mA, 5.5V < VIN < 25V 4.75 -- 5.25 V LDO5 Output Current I SHORT5 V BYP1 = 0V, VLDO5 = 4.5V -- 225 -- mA 5V Switchover Threshold V BYP1TH Falling Edge, Rising Edge with FB1 Regulation Point 4.53 4.66 4.79 V 5V Switch RDS(ON) R BYPSW V BYP1 = 5V, ILDO5 = 50mA -- 1.5 3 Ω VBYP1 = 0V, ILDO3 < 100mA 3.2 3.3 3.46 V LDO3 Output Voltage V LDO3 VBYP1 = 5V, ILDO3 < 100mA 3.2 3.3 3.46 LDO3 Output Current I SHORT3 V BYP1 = 0V, VLDO3 = 2.9V -- 150 -- mA UVLO Rising Edge -- 4.35 4.5 LDO5 UVLO Threshold V UVLO5 Falling Edge 3.9 4.05 4.2 V LDO3 UVLO Threshold V UVLO3 Both SMPS Off -- 2.2 -- Power Good PGOOD Threshold V PGOOD PGOOD Detect, Rising edge with soft-start delay time. Hysteresis = 2.5% −14 −10 −6 % PGOOD Propagation Delay t PD_PGOOD Falling Edge -- 5 -- μs
DS8239A/B/C-06 October 2012 www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Parameter Symbol Test Conditions Min Typ Max Unit PGOOD Leakage Current I LK_PGOOD High State, Forced to 5.5V -- -- 1 μA PGOOD Output Low Voltage V SINK_PGOOD I SINK = 4mA -- -- 0.4 V SECFB Power Good Threshold VSFB_PGOOD SECFB with Respect to 2V (RT8239B/C) 40 50 60 % Fault Detection Over Voltage Protection Trip Threshold VOVP OVP Detect, FBx Rising Edge 108 112 116 % Over Voltage Protection Propagation Delay tDLY_OVP Rising Edge -- 5 -- μs VUVP UVP Detect, FBx Falling Edge. 53 58 63 % Under Voltage Protection Trip Threshold VSFB_UVP UVP Detect, SECFB Falling Edge. 0.8 -- 1.2 V Under Voltage Protection Shutdown Blanking Time tSSHx From ENTRIPx or ENM Enable -- 5 -- ms Thermal Shutdown Thermal Shutdown TSD -- 150 -- °C Thermal Shutdown Hysteresis ΔTSD -- 10 -- °C Logic Input ENTRIPx Input Voltage V ENTRIPx Clear Fault Level/SMPSx Off Level 4.5 -- -- V Rising Edge Threshold 1.2 1.6 2 Falling Edge Threshold 0.9 0.95 1 ENLDO Input Voltage V ENLDO When ENLDO is Floating (Default Enable) 2.1 -- -- V Clear Fault Level/SMPSs Off Level -- -- 0.8 SMPSs On, DEM Operation 2.3 -- 3.6 ENM Input Voltage (RT8239A) VENM SMPSs On, Ultrasonic Mode Operation 4.5 -- -- V IFBx V FBx = 0V or 5V −1 -- 1 IP13 ENM/SECFB = 0V or 5V −1 -- 1 Input Leakage Current IENLDO ENLDO = 0V or 5V −1 -- 3 μA Internal BOOT Switch Internal Boost Charging Switch On-Resistance RBOOTx LDO5 to BOOTx, 10mA -- -- 90 Ω Power MOSFET Drivers RUGATEsr Source, V BOOTx − VUGATEx = 0.1V -- 5 8 UGATEx On-Resistance RUGATEsk Sink, V UGATEx − VPHASEx = 0.1V -- 2 4 Ω RLGATEsr Source, V LDO5 − VLGATEx = 0.1V -- 5 8 LGATEx On-Resistance RLGATEsk Sink, V LGATEx = 0.1V -- 1.5 3 Ω tLGATERx UGATEx Off to LGATEx On -- 30 -- Dead Time tUGATERx LGATEx Off to UGATEx On -- 40 -- ns
DS8239A/B/C-06 October 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Note 1. Stresses beyond those listed “Absolute Maximum Ratings ” may cause permanent damage to the device. These are stress ratings only, and 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 may affect device reliability. Note 2. θ JA is measured at T A = 25 °C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions.
DS8239A/B/C-06 October 2012 www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Typical Operating Characteristics VOUT2 Efficiency vs. Load Current 100 0.001 0.01 0.1 1 10 Load Current (A) Efficiency (%) VIN = 12V, RTON = 100kΩ, VENTRIP1 = 5V, VENTRIP2 = 1.5V, ENLDO = 5V DEM ASM VOUT2 Efficiency vs. Load Current 100 0.001 0.01 0.1 1 10 Load Current (A) Efficiency (%) VIN = 20V, RTON = 100kΩ, VENTRIP1 = 5V, VENTRIP2 = 1.5V, ENLDO = 5V DEM ASM VOUT2 Efficiency vs. Load Current 100 0.001 0.01 0.1 1 10 Load Current (A) Efficiency (%) VIN = 8V, RTON = 100kΩ, VENTRIP1 = 5V, VENTRIP2 = 1.5V, ENLDO = 5V DEM ASM VOUT1 Efficiency vs. Load Current 100 0.001 0.01 0.1 1 10 Load Current (A) Efficiency (%) VIN = 20V, RTON = 100kΩ, VENTRIP1 = 1.5V VENTRIP2 = 5V, ENLDO = 5V DEM ASM VOUT1 Efficiency vs. Load Current 100 0.001 0.01 0.1 1 10 Load Current (A) Efficiency (%) VIN = 8V, RTON = 100kΩ, VENTRIP1 = 1.5V VENTRIP2 = 5V, ENLDO = 5V DEM ASM VOUT1 Efficiency vs. Load Current 100 0.001 0.01 0.1 1 10 Load Current (A) Efficiency (%) VIN = 12V, RTON = 100kΩ, VENTRIP1 = 1.5V VENTRIP2 = 5V, ENLDO = 5V DEM ASM
DS8239A/B/C-06 October 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. VOUT1 Switching Frequency vs. Load Current 100 120 140 160 180 200 220 240 0.001 0.01 0.1 1 10 Load Current (A) Switching Frequency (kHz) 1 VIN = 8V, RTON = 100kΩ, ENLDO = VIN, VENTRIP1 = 1.5V, VENTRIP2 = 5V ASM DEM VOUT1 Switching Frequency vs. Load Current 100 120 140 160 180 200 220 240 260 0.001 0.01 0.1 1 10 Load Current (A) Switch Frequency (kHz) 1 VIN = 12V, RTON = 100kΩ, ENLDO = VIN, VENTRIP1 = 1.5V, VENTRIP2 = 5V ASM DEM VOUT1 Switching Frequency vs. Load Current 100 120 140 160 180 200 220 240 260 0.001 0.01 0.1 1 10 Load Current (A) Switching Frequency (kHz) 1 VIN = 20V, RTON = 100kΩ, ENLDO = VIN, VENTRIP1 = 1.5V, VENTRIP2 = 5V ASM DEM VOUT2 Switching Frequency vs. Load Current 100 120 140 160 180 200 220 240 260 280 300 0.001 0.01 0.1 1 10 Load Current (A) Switching Frequency (kHz) 1 VIN = 12V, RTON = 100kΩ, ENLDO = VIN, VENTRIP1 = 5V, VENTRIP2 = 1.5V ASM DEM VOUT2 Switching Frequency vs. Load Current 100 120 140 160 180 200 220 240 260 280 300 0.001 0.01 0.1 1 10 Load Current (A) Switching Frequency (kHz) 1 VIN = 20V, RTON = 100kΩ, ENLDO = VIN, VENTRIP1 = 5V, VENTRIP2 = 1.5V ASM DEM VOUT2 Switching Frequency vs. Load Current 100 120 140 160 180 200 220 240 260 280 0.001 0.01 0.1 1 10 Load Current (A) Switching Frequency (kHz) 1 VIN = 8V, RTON = 100kΩ, ENLDO = VIN, VENTRIP1 = 5V, VENTRIP2 = 1.5V ASM DEM
DS8239A/B/C-06 October 2012 www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. VOUT2 Output Voltage vs. Load Current 3.372 3.378 3.384 3.390 3.396 3.402 3.408 3.414 3.420 0.001 0.01 0.1 1 10 Load Current (A) Output Voltage (V) VIN = 12V, RTON = 100kΩ, ENLDO = VIN, VENTRIP1 = 5V, V ENTRIP2 = 1.5V ASM DEM VOUT1 Output Voltage vs. Load Current 5.010 5.013 5.016 5.019 5.022 5.025 5.028 5.031 5.034 0.001 0.01 0.1 1 10 Load Current (A) Output Voltage (V) VIN = 12V, RTON = 100kΩ, ENLDO = VIN, VENTRIP1 = 1.5V, V ENTRIP2 = 5V ASM DEM Standby Input Current vs. Input Voltage 226 228 230 232 234 236 238 240 6 8 10 12 14 16 18 20 22 24 26 Input Voltage (V) Standby Input Current (μA) 1 VENTRIP1 = VENTRIP2 = 5V, ENLDO = VIN, No Load LDO5 Output Voltage vs. Output Current 5.048 5.052 5.056 5.060 5.064 5.068 5.072 0 1 02 03 04 05 06 07 08 09 0 1 0 0 Output Current (mA) Output Voltage (V) VIN = 12V, VENTRIP1 = VENTRIP2 = 5V, ENLDO = VIN LDO3 Output Voltage vs. Output Current 3.334 3.336 3.338 3.340 3.342 3.344 3.346 3.348 3.350 3.352 3.354 0 1 02 03 04 05 06 07 08 09 0 1 0 0 Output Current (mA) Output Voltage (V) VIN = 12V, VENTRIP1 = VENTRIP2 = 5V, ENLDO = VIN No Load Battery Current vs. Input Voltage 0.1 100 6 7 8 9 1 01 11 21 31 41 51 61 71 81 92 02 12 22 32 42 5 Input Voltage (V) Battery Current (mA) RTON = 100kΩ, VENTRIP1 = VENTRIP2 =1.5V, EVLDO = VIN ASM DEM
DS8239A/B/C-06 October 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Power On from ENLDO Time (2ms/Div) VIN = 12V, VENTRIP1 = VENTRIP2 = 1.5V LDO5 (2V/Div) LDO3 (2V/Div) ENLDO (10V/Div) CP (10V/Div) ENLDO = VIN, RTON = 100kΩ, No Load Shutdown Input Current vs. Input Voltage 6 8 10 12 14 16 18 20 22 24 26 Input Voltage (V) Shutdown Input Current ( μA) 1 VENTRIP1 = VENTRIP2 = 5V, ENLDO = GND, No Load Power Off from ENTRIP1 Time (4ms/Div) RT8239B/C VIN = 12V, VENTRIP1 = V ENTRIP2 = 1.5V, ENLDO = VIN, RTON = 100kΩ, No Load VIN = 12V, VENTRIP1 = V ENTRIP2 = 1.5V, ENLDO = VIN, RTON = 100kΩ, No Load VOUT1 (2V/Div) PGOOD (5V/Div) ENTRIP1 (5V/Div) RT8239B/C Power On from ENTRIP1 Time (1ms/Div) VIN = 12V, VENTRIP1 = V ENTRIP2 = 1.5V, ENLDO = VIN, RTON = 100kΩ, No Load VOUT1 (2V/Div) PGOOD (5V/Div) ENTRIP1 (5V/Div) RT8239B/C Power Off from ENM Time (10ms/Div) VOUT1 (5V/Div) PGOOD (5V/Div) ENM (5V/Div) VOUT2 (5V/Div) RT8239A VIN = 12V, VENM = 5V, RTON = 100kΩ, VENTRIP1 = VENTRIP2 = 1.5V, ENLDO = VIN, No Load Power On from ENM Time (1ms/Div) VOUT1 (2V/Div) PGOOD (5V/Div) ENM (5V/Div) RT8239A VOUT2 (2V/Div) VENTRIP1 = VENTRIP2 = 1.5V, ENLDO = VIN, No Load VIN = 12V, VENM = 5V, RTON = 100kΩ
DS8239A/B/C-06 October 2012 www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. OVP Time (10ms/Div) VIN = 12V, RTON = 100kΩ, ENLDO = VIN, No Load VOUT1 (2V/Div) PGOOD (5V/Div) VOUT2 (2V/Div) UVP Time (100 μs/Div) VIN = 12V, RTON = 100kΩ, ENLDO = VIN VOUT1 (2V/Div) LGATE1 (10V/Div) UGATE1 (50V/Div) PGOOD (5V/Div) VOUT2 DEM-MODE Load Transient Response Time (20 μs/Div) ENLDO = VIN, IOUT2 =1A to 8A VOUT2_AC (50mV/Div) Inductor Current (5A/Div) UGATE2 (20V/Div) LGATE2 (5V/Div) VIN = 12V, RTON = 100kΩ, Power Off from ENTRIP2 Time (20ms/Div) VIN = 12V, VENTRIP1 = V ENTRIP2 = 1.5V, ENLDO = VIN, RTON = 100kΩ, No Load VOUT2 (1V/Div) PGOOD (10V/Div) ENTRIP2 (5V/Div) RT8239B/C VOUT1 DEM-MODE Load Transient Response Time (20 μs/Div) VIN = 12V, RTON = 100kΩ, ENLDO = VIN, IOUT1 =1A to 8A VOUT1_AC (50mV/Div) Inductor Current (5A/Div) UGATE1 (20V/Div) LGATE1 (5V/Div) Power On from ENTRIP2 Time (1ms/Div) VIN = 12V, VENTRIP1 = V ENTRIP2 = 1.5V, ENLDO = VIN, RTON = 100kΩ, No Load VOUT2 (1V/Div) PGOOD (5V/Div) ENTRIP2 (5V/Div) RT8239B/C
DS8239A/B/C-06 October 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation.
Application Information
The RT8239A/B/C is a dual, Mach ResponseTM DRVTM mode synchronous buck controller targeted for notebook system power supply solutions. RICHTEK's Mach Response TM technology provides fast response to load steps. The topology circumvents the poor load transient timing problems of fixed frequency current mode PWMs while avoiding the problems caused by widely varying switching frequency in conventional constant on-time and constant off-time PWM schemes. A special adaptive on- time control trades off the performance and efficiency over wide input voltage range. The RT8239A/B/C includes 5V (LDO5) and 3.3V (LDO3) linear regulators. The LDO5 linear regulator steps down the battery voltage to supply both internal circuitry and gate drivers. The synchronous switch gate drivers are directly powered by LDO5. When V OUT1 rises above 4.66V, an automatic circuit disconnects the linear regulator and allows the device to be powered by V OUT1 via the BYP1 pin. PWM Operation The Mach ResponseTM DRVTM mode controller relies on the output filter capacitor's Effective Series Resistance (ESR) to act as a current sense resistor, so that the output ripple voltage provides the PWM ramp signal. Referring to the RT8239A/B/C's Function Block Diagram, the synchronous high side MOSFET will be turned on at the beginning of each cycle. After the internal one-shot timer expires, the MOSFET will be turned off. The pulse width of this one-shot is determined by the converter's input voltage and the output voltage to keep the frequency fairly constant over the entire input voltage range. Another one- shot sets a minimum off-time (400ns typ). The on-time one-shot will be triggered if the error comparator is high, the low side switch current is below the current limit threshold, and the minimum off-time one-shot has timed out. PWM Frequency and On-time Control For each specific input voltage range, the Mach Response TM control architecture runs with pseudo constant frequency by feed forwarding the input and output voltage into the on-time one-shot timer. The high side switch on- time is inversely proportional to the input voltage as measured by V IN and proportional to the output voltage. There are two benefits of a constant switching frequency. First, the frequency can be selected to avoid noise sensitive regions such as the 455kHz IF band. Second, the inductor ripple current operating point remains relatively constant, resulting in easy design methodology and predictable output voltage ripple. The frequency for 3V SMPS is set higher than the frequency for 5V SMPS. This is done to prevent audio frequency “beating” between the two sides, which switch asynchronously for each side. The TON pin is connected to GND through the external resistor, R TON, to set the switching frequency. The RT8239A/B/C adaptively changes the operation frequency according to the input voltage. Higher input voltage usually comes from an external adapter, so the RT8239A/B/C operates with higher frequency to have better performance. Lower input voltage usually comes from a battery, so the RT8239A/B/C operates with lower switching frequency for lower switching losses. For a specific input voltage range, the switching cycle period is given by : For 5.5V < V IN < 6.5V : t S1 = 61.28p x RTON t S2 = 44.43p x RTON For 6.5V < VIN < 12V : t S1 = 51.85p x RTON t S2 = 44.43p x RTON For 12V < VIN < 25V : t S1 = 45.75p x RTON t S2 = 39.2p x RTON The on-time guaranteed in the Electrical Characteristics table is influenced by switching delays in the external high side power MOSFET. Two external factors that influence switching frequency accuracy are resistive drops in the two conduction loops (including inductor and PC board resistance) and the dead time effect. These effects are the largest contributors to the change of frequency with changing load current. The dead time effect increases the effective on-time by reducing the switching frequency
©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. is the on-time calculated by the RT8239A/B/C. Figure 3. Boundary condition of CCM/DEM operation. This is normal and results in high efficiency. (especially at low input voltage levels). Table 1. Operation Mode Setting the inductor current reaches the continuous conduction.
©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Figure 4. “Valley” Current Limit low side MOSFET to induce a negative inductor current. disconnects the internal linear regulator. The RT8239A/B/C has cycle-by-cycle current limit control. the PWM is not allowed to initiate a new cycle (Figure 4). threshold by an amount equal to the inductor ripple current. resistance, inductor value, and battery and output voltage. is charged to C2 voltage minus a diode drop through D3. dropped across the Schottky diode. will occur to refresh the charge pump driven by LGATEx.
DS8239A/B/C-06 October 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Output Over Voltage Protection (OVP) The output voltage can be continuously monitored for over voltage. If the output voltage exceeds 12% of its set voltage threshold, the over voltage protection is triggered and the LGATEx low side gate drivers are forced high. This activates the low side MOSFET switch, which rapidly discharges the output capacitor and pulls the input voltage downward. The RT8239A/B/C is latched once OVP is triggered and can only be released by either toggling ENLDO, ENTRIPx or cycling VIN. There is a 5 μs delay built into the over voltage protection circuit to prevent false transition. Note that latching LGATEx high will cause the output voltage to dip slightly negative due to previously stored energy in the LC tank circuit. For loads that cannot tolerate a negative voltage, place a power Schottky diode across the output to act as a reverse polarity clamp. If the over voltage condition is caused by a short in high side switch, turning the low side MOSFET on 100% will create an electrical short between the battery and GND, hence blowing the fuse and disconnecting the battery from the output. Output Under Voltage Protection (UVP) The output voltage can be continuously monitored for under voltage. If the output is less than 58% of its set voltage threshold, the under voltage protection will be triggered and then both UGATEx and LGATEx gate drivers will be forced low. The UVP is ignored for at least 5ms (typ.) after a start up or a rising edge on ENTRIPx. Toggle ENTRIPx or cycle VIN to reset the UVP fault latch and restart the controller. Thermal Protection The RT8239A/B/C features thermal shutdown to prevent damage from excessive heat dissipation. Thermal shutdown occurs when the die temperature exceeds 150°C. All internal circuitry is inactive during thermal shutdown. The RT8239A/B/C triggers thermal shutdown if LDOx is not supplied from V OUTx, while input voltage on VIN and drawing current from LDOx are too high. Nevertheless, even if LDOx is supplied from V OUTx, overloading LDOx can cause large power dissipation on automatic switches, which may still result in thermal shutdown. Discharge Mode (Soft Discharge) When ENTRIPx is low and a transition to standby or shutdown mode occurs, or the output under voltage fault latch is set, the output discharge mode will be triggered. During discharge mode, an internal switch creates a path for discharging the output capacitors' residual charge to GND. Shutdown Mode SMPS1, SMPS2, LDO3 and LDO5 all have independent enabling control. Drive ENLDO, ENTRIP1 and ENTRIP2 below the precise input falling edge trip level to place the RT8239A/B/C in its low power shutdown state. The RT8239A/B/C consumes only 20μA of input current while in shutdown. When shutdown mode is activated, the reference turns off. The accurate 0.95V falling edge threshold on ENLDO can be used to detect a specific analog voltage level and to shutdown the device. Once in shutdown, the 1.6V rising edge threshold activates, providing sufficient hysteresis for most applications. Power Up Sequencing and On/Off Controls (ENTRIPx, ENM) ENTRIP1 and ENTRIP2 control SMPS power up sequencing. When the RT8239A/B/C is applied in the single channel mode, ENTRIPx disables the respective output when ENTRIPx voltage rises above 4.5V. Furthermore, when the RT8239A is applied in the dual channel mode, the outputs are enabled when ENM voltage rises above 2.3V.
©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Protection Either output > 112% of the nominal level. LGATEx is forced high. LDO3 and LDO5 are active. enter discharge mode. LDO3 and LDO5 are active. ENLDO = high. LDO3 and LDO5 are active. Shutdown ENLDO = low All circuitry are off. Table 2. Power up Sequencing (RT8239A)
©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Figure 7. Setting VOUTx with a resistive voltage divider the average inductor current. The calculation above shall serve as a general reference. considered when improving transient response. calculated from below equations.
©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. on the maximum power dissipation. Figure 8. Derating Curve of Maximum Power Dissipation starting a layout with the RT8239A/B/C. to high-voltage switching node. 0.65mm (25 mils) or wider trace. inductor, should be as short and wide as possible.
DS8239A/B/C-06 October 2012www.richtek.com Richtek Technology Corporation 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnish ed by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringeme nts of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of R ichtek or its subsidiaries. Outline Dimension 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 0.150 0.250 0.006 0.010 D 2.900 3.100 0.114 0.122 D2 1.650 1.750 0.065 0.069 E 2.900 3.100 0.114 0.122 E2 1.650 1.750 0.065 0.069 e 0.400 0.016 L 0.350 0.450 0.014 0.018 W-Type 20L QFN 3x3 Package Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. DETAIL A Pin #1 ID and Tie Bar Mark Options 2 2