RT8206AGQW

RT8206A/B High Efficiency, Main Power Supply Controllers for Notebook Computers General Description Features The RT8206A/B dual step-down, Switch Mode Power Supply (SMPS) controller generates logic supply voltages in battery powered systems. The RT8206A/B includes two Pulse Width Modulation (PWM) controllers fixed at 5V/3.3V or adjustable from 2V to 5.5V. An optional external charge pump can be monitored through SECFB (RT8206A). This device also features a linear regulator providing a fixed 5V output. The linear regulator provides up to 70mA output current with automatic linear regulator bootstrapping to the BYP input. The RT8206A/B includes on-board power up sequencing, the power good outputs, internal soft-start, and internal soft-discharge output that prevents negative voltages on shutdown. z A constant on-time PWM control scheme operates without sense resistors and provides 100ns response to load transients while maintaining a relatively constant switching frequency. The unique ultrasonic mode maintains the switching frequency above 25kHz, which eliminates noise in audio applications. Other features include Diode Emulation Mode (DEM), which maximizes efficiency in light load applications, and fixed frequency PWM mode, which reduces RF interference in sensitive application. The RT8206A/B is available in the WQFN-32L 5x5 package. z z z z z z z z z z z z z z Wide Input Voltage Range 6V to 25V Dual Fixed 5V/3.3V Outputs or Adjustable from 2V to 5.5V, 1.5% Accuracy Secondary Feedback Input Maintains Charge Pump Voltage (RT8206A) Independent Enable and Power Good 5V Fixed LDO Output : 70mA 2V Reference Voltage ±1% : 50μ μA Constant ON-Time Control with 100ns Load Step Response Frequency Selectable via TON Setting RDS(ON) Current Sensing and Programmable Current Limit Selectable PWM, DEM or Ultrasonic Mode Internal Soft-Start with 5 Steps Current Limiting and Soft-Discharge High Efficiency Up to 97% 5mW Quiescent Power Dissipation Thermal Shutdown RoHS Compliant and Halogen Free Applications z z Notebook and Sub-Notebook Computers 3-Cell and 4-Cell Li+ Battery-Powered Devices Ordering Information Marking Information RT8206 RT8206AGQW RT8206AGQW : Product Number Package Type QW : WQFN-32L 5x5 (W-Type) Lead Plating System G : Green (Halogen Free and Pb Free) A : With SECFB B : Without SECFB Note : Richtek products are : ` RoHS compliant and compatible with the current require- ` Suitable for use in SnPb or Pb-free soldering processes. ments of IPC/JEDEC J-STD-020. DS8206A/B-06 August 2011 RT8206A GQW YMDNN YMDNN : Date Code RT8206BGQW RT8206BGQW : Product Number RT8206B GQW YMDNN YMDNN : Date Code www.richtek.com 1 RT8206A/B Pin Configurations 25 24 2 23 3 22 ENLDO NC VIN LDO NC 4 21 GND 5 BOOT2 LGATE2 PGND GND SECFB PVCC LGATE1 BOOT1 20 6 19 7 18 33 17 32 31 30 29 28 27 26 25 REF TON VCC 1 24 2 23 3 22 ENLDO NC VIN LDO NC 4 21 GND 5 20 6 19 7 18 33 17 9 10 11 12 13 14 15 16 9 10 11 12 13 14 15 16 BYP FB1 ILIM1 PGOOD1 EN1 UGATE1 PHASE1 BYP VOUT1 FB1 ILIM1 PGOOD1 EN1 UGATE1 PHASE1 8 VOUT1 8 PHASE2 PHASE2 26 UGATE2 UGATE2 27 EN2 EN2 28 PGOOD2 PGOOD2 29 SKIP SKIP 30 VOUT2 VOUT2 31 1 ILIM2 ILIM2 32 REF TON VCC FB2 FB2 (TOP VIEW) WQFN-32L 5x5 WQFN-32L 5x5 RT8206A RT8206B BOOT2 LGATE2 PGND GND NC PVCC LGATE1 BOOT1 Typical Application Circuit VIN 6V to 25V R14 3.9 C1 10µF RT8206A/B 6 VIN C18 0.1µF Q1 C3 220µF PHASE2 25 R3 0 17 LGATE2 23 18 LGATE1 9 C8 C9 1µF C7 0.1µF 3 VCC 0.1µF C19 C11 0.1µF R7 0 C16 1µF 11 FB1 32 FB2 ILIM2 19 PVCC SKIP 7 LDO C15 0.22µF R6 100k 28 R13 100k C17 220µF R10 PVCC PVCC 5V Enable ON 3.3V Enable OFF LDO Control 31 TON 2 GND VOUT2 3.3V C14 13 EN1 14 EN2 27 20 SECFB/NC R12 39k L2 4.7µH Q4 ILIM1 12 R11 200k CP PGOOD1 C12 10µF C13 10µF Q2 R8 0 VOUT2 30 REF 1 ENLDO 4 D4 R9 0 PGND 22 PGOOD2 D2 D3 BYP 10 VOUT1 C5 0.1µF D1 BOOT1 16 PHASE1 C4 C6 0.1µF 24 15 UGATE1 Q3 R5 BOOT2 R4 0 C2 0.1µF L1 6.8µH VOUT1 5V UGATE2 26 29 VIN R1 180k R2 180k Frequency Control PWM/DEM/Ultrasonic 21, 33 (Exposed Pad) C10 4.7µF Figure 1. Fixed Voltage Regulator www.richtek.com 2 DS8206A/B-06 August 2011 RT8206A/B VIN 6V to 25V R14 3.9 C1 10µF RT8206A/B 6 VIN C18 0.1µF R4 0 Q1 R3 0 C2 0.1µF L1 6.8µH VOUT1 5V C3 220µF BOOT2 15 UGATE1 17 18 LGATE1 9 C4 D1 C6 0.1µF BYP C9 1µF C7 0.1µF C8 0.1µF C23 C20 0.1µF R15 15k CP C19 20 SECFB/NC R12 39k 11 FB1 R7 0 R16 10k C16 1µF C10 4.7µF 19 PVCC 7 LDO L2 4.7µH Q4 C17 220µF R10 R17 11.5k C15 0.22µF SKIP GND C22 C21 0.1µF PVCC PVCC ON 3.3V Enable OFF LDO Control VIN R1 180k R2 180k 31 29 R18 10k 5V Enable ILIM1 12 TON 2 R6 100k R13 100k PGOOD2 28 ILIM2 VOUT2 3.3V C14 13 ENLDO 4 R11 200k C11 0.1µF VOUT2 30 FB2 32 REF 1 C12 10µF R8 0 PGND 22 EN1 14 EN2 27 D4 C13 10µF Q2 LGATE2 23 PGOOD1 3 VCC 24 R9 0 PHASE2 25 10 VOUT1 C5 0.1µF D2 D3 BOOT1 16 PHASE1 Q3 R5 UGATE2 26 Frequency Control PWM/DEM/Ultrasonic 21, 33 (Exposed Pad) Figure 2. Adjustable Voltage Regulator DS8206A/B-06 August 2011 www.richtek.com 3 RT8206A/B Function Block Diagram TON SKIP BOOT1 BOOT2 UGATE1 UGATE2 PHASE1 PVCC PHASE2 PVCC SMPS1 PWM Buck Controller LGATE1 PGND SMPS2 PWM Buck Controller LGATE2 VOUT2 FB2 ILIM2 PGOOD2 VOUT1 FB1 ILIM1 PGOOD1 GND SW Threshold VCC PVCC ENLDO EN1 EN2 BYP Internal Logic LDO Power On Sequence Clear Fault Latch Thermal Shutdown LDO REF REF VIN Function Block Diagram TON VIN UGATE On-Time Compute VOUT TON Q 1-Shot R TOFF TRIG 1-Shot Q TRIG REF - - Comp + + + - LGATE FB 1.1 x VREF Over Voltage + Fault Latch - VCC - 0.7 x VREF Blanking Time + Under Voltage + Current Limit - 0.9 x VREF PGOOD + ILIM - SS Time + 25kHz Detector Zero Detector + - PHASE - SKIP PWM Controller (One Side) www.richtek.com 4 DS8206A/B-06 August 2011 RT8206A/B Functional Pin Description REF (Pin 1) VOUT1 (Pin 10) 2V Reference Output. Bypass to GND with a 0.22μF capacitor. REF can source up to 50μA for external loads. Loading REF degrades FBx and output accuracy according to the REF load regulation error. SMPS1 Output Voltage Sense Input. Connect this pin to the SMPS1 output. VOUT1 is an input to the Constant on-time-PWM one-shot circuit. It also serves as the SMPS1 feedback input in fixed voltage mode. TON (Pin 2) FB1 (Pin 11) Frequency Select Input. (VOUT1/VOUT2 switching frequency, respectively) : SMPS1 Feedback Input. Connect FB1 to VCC or GND for fixed 5V operation. Connect FB1 to a resistive voltage divider from VOUT1 to GND to adjust output from 2V to 5.5V. TON = VCC, (200kHz / 250kHz) TON = REF, (300kHz / 375kHz) TON = GND, (400kHz / 500kHz) VCC (Pin 3) Analog Supply Voltage Input for the PWM Core. Bypass to GND with a 1μF ceramic capacitor ENLDO (Pin 4) LDO Enable Input. The REF/LDO is enabled if ENLDO is within logic high level and disable if ENLDO is less than the logic low level. NC (Pin 5, 8) No Internal Connection. VIN (Pin 6) Power supply Input. VIN is used for the constant on-time PWM one shot circuits. VIN is also used to power the linear regulators. The linear regulators are powered by SMPS1 if VOUT1 is set greater than 4.66V and BYP is tied to VOUT1. Connect VIN to the battery input and bypass with a 1μF capacitor. LDO (Pin 7) Linear Regulator Output. LDO can provide a total of 70mA external loads. The LDO regulates a fixed 5V output. When the BYP is within 5V switchover threshold, the internal regulator shuts down and the LDO output pin connects to BYP through a 1.5Ω switch. Bypass LDO output with a minimum of 4.7μF ceramic. BYP (Pin 9) BYP is the switchover source voltage input for the LDO. DS8206A/B-06 August 2011 ILIM1 (Pin 12) SMPS1 Current Limit Adjustment. The GND − PHASE1 current limit threshold is 1/10th the voltage seen at ILIM1 over a 0.5V to 2V range. There is an internal 5μA current source from VCC to ILIM1. The logic current limit threshold is default to 100mV if ILIM1 is higher than (VCC − 1V). PGOOD1 (Pin 13) SMPS1 Power Good Open-Drain Output. PGOOD1 is low when the SMPS1 output voltage is more than 7.5% below the normal regulation point or during soft-start. PGOOD1 is high impedance when the output is in regulation and the soft-start circuit has terminated. PGOOD1 is low in shutdown. EN1 (Pin 14) SMPS1 Enable Input. The SMPS1 will be enabled if EN1 is greater than the logic high level and disabled if EN1 is less than the logic low level. If EN1 is connected to REF, the SMPS1 starts after the SMPS2 reaches regulation (delay start). Drive EN1 below 0.8V to clear fault level and reset the fault latches. UGATE1 (Pin 15) High Side MOSFET Floating Gate Driver Output for SMPS1. UGATE1 swings between PHASE1 and BOOT1. PHASE1 (Pin 16) Inductor Connection for SMPS1. PHASE1 is the internal lower supply rail for the UGATE1 high side gate driver. PHASE1 is the current sense input for the SMPS1. www.richtek.com 5 RT8206A/B BOOT1 (Pin 17) PHASE2 (Pin 25) Boost Flying Capacitor Connection for SMPS1. Connect to an external capacitor according to the typical application circuits. Inductor Connection for SMPS2. PHASE2 is the internal lower supply rail for the UGATE2 high side gate driver. PHASE2 is the current sense input for the SMPS2. LGATE1 (Pin 18) UGATE2 (Pin 26) SMPS1 Synchronous-Rectifier Gate drive Output. LGATE1 swings between PGND and PVCC. High Side MOSFET Floating Gate Driver Output for SMPS2. UGATE2 swings between PHASE2 and BOOT2. PVCC (Pin 19) EN2 (Pin 27) PVCC is the supply voltage for the low side MOSFET driver LGATEx. Connect a 5V power source to the PVCC pin (bypass with 1μF MLCC capacitor to PGND if necessary). There is an internal 10Ω connecting from PVCC to VCC. Make sure that both VCC and PVCC are bypassed with 1μF MLCC capacitors. SMPS2 Enable Input. The SMPS2 will be enabled if EN2 is greater than the logic high level and be disabled if EN2 is less than the logic low level. If EN2 is connected to REF, the SMPS2 starts after the SMPS1 reaches regulation (delay start). Drive EN2 below 0.8V to clear fault level and reset the fault latches. SECFB (Pin 20) (RT8206A) PGOOD2 (Pin 28) The SECFB is used to monitor the optional external 14V charge pump. Connect a resistive voltage divider from the 14V charge pump output to GND to detect the output. If SECFB drops below the threshold voltage, LGATE1 will be turned on for 300ns. This will refresh the external charge pump driven by LGATE1 without over discharging the output voltage. SMPS2 Power Good Open-Drain Output. PGOOD2 is low when the SMPS2 output voltage is more than 7.5% below the normal regulation point or during soft-start. PGOOD2 is high impedance when the output is in regulation and the soft-start circuit has terminated. PGOOD2 is low in shutdown. SKIP (Pin 29) NC (Pin 20) (RT8206B) SMPS Operation Mode Control. No Internal Connection. SKIP = GND : DEM operation GND [Pin 21, 33 (Exposed Pad)] SKIP = REF : Ultrasonic Mode operation Analog Ground for both SMPS and LDO. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. SKIP = VCC : PWM operation. VOUT2 (Pin 30) Power Ground for SMPS controller. Connect PGND externally to the underside of the exposed pad. SMPS2 Output Voltage Sense Input. Connect this pin to the SMPS2 output. VOUT2 is an input to the constant on-time-PWM one-shot circuit. It also serves as the SMPS2 feedback input in fixed voltage mode. LGATE2 (Pin 23) ILIM2 (Pin 31) SMPS2 Synchronous-Rectifier Gate drive Output. LGATE2 swings between PGND and PVCC. SMPS2 Current Limit Adjustment. The GND − PHASE2 current limit threshold is 1/10th the voltage seen at ILIM2 over a 0.5V to 2V range. There is an internal 5μA current source from VCC to ILIM2. The logic current limit threshold is default to 100mV value if ILIM2 is higher than (VCC − 1V). PGND (Pin 22) BOOT2 (Pin 24) Boost Flying Capacitor Connection for SMPS2. Connect this pin to an external capacitor according to the typical application circuits. www.richtek.com 6 DS8206A/B-06 August 2011 RT8206A/B FB2 (Pin 32) SMPS2 Feedback Input. Connect FB2 to VCC or GND for fixed 3.3V operation. Connect FB2 to a resistive voltage divider from VOUT2 to GND to adjust output from 2V to 5.5V. DS8206A/B-06 August 2011 www.richtek.com 7 RT8206A/B Absolute Maximum Ratings z z z z z z z z z z z z z z (Note 1) VIN, ENLDO to GND ---------------------------------------------------------------------------------------------- –0.3V to 30V PHASEx to GND DC --------------------------------------------------------------------------------------------------------------------- –0.3V to 30V