RT8205A RICHTEK [Richtek Technology Corporation], RT8205A Datasheet
RT8205A
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RT8205A Summary of contents
Page 1
... The linear regulator each provides up to 70mA output current with automatic linear-regulator bootstrapping to the PWM outputs. The RT8205A/B/C includes on-board power-up sequencing, the power-good output, internal soft- start, and internal soft-discharge output that prevents negative voltages on shutdown ...
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... FB1 VREG5 2 17 REF VIN 3 16 GND TONSEL PGND 4 15 FB2 SKIPSEL ENTRIP2 RT8205B WQFN-24L 4x4 RT8205A 10 16 UGATE2 VIN 9 BOOT2 21 UGATE1 11 PHASE2 12 22 LGATE2 BOOT1 20 PHASE1 7 VOUT2 19 LGATE1 17 VREG5 23 24 PGOOD VOUT1 8 3 REF VREG3 ...
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... VOUT2 19 LGATE1 VREG5 24 PGOOD VOUT1 VREG3 3 REF ENTRIP1 2 FB1 5 ENTRIP2 FB2 TONSEL 18 SECFB SKIPSEL PGND GND registered trademark of Richtek Technology Corporation. RT8205A/B BSC119 N03S BSC119 N03S Exposed Pad (25 BSC119 N03S 9 11 ...
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... RT8205A/B/C For Adjustable Voltage Regulator Q1 BSC119 N03S Q3 BSC119 N03S ON OFF Q1 BSC119 N03S Q3 BSC119 N03S CP Copyright © 2012 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 RT8205A 10 16 UGATE2 VIN 9 BOOT2 21 UGATE1 11 PHASE2 12 22 LGATE2 BOOT1 20 PHASE1 7 VOUT2 19 LGATE1 5 FB2 1 ENTRIP1 24 VOUT1 6 ENTRIP2 ...
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... UGATE2 VIN 9 BOOT2 21 UGATE1 11 PHASE2 12 22 LGATE2 BOOT1 20 PHASE1 7 VOUT2 19 LGATE1 5 FB2 24 VOUT1 1 ENTRIP1 2 FB1 6 ENTRIP2 Exposed Pad (25) GND 3 REF 17 VREG5 23 PGOOD 8 VREG3 18 SECFB 4 TONSEL 14 SKIPSEL PGND is a registered trademark of Richtek Technology Corporation. RT8205A/B/C Q2 BSC119 N03S Q4 BSC119 N03S www.richtek.com 5 ...
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... RT8205A/B/C Function Block Diagram BOOT1 UGATE1 PHASE1 LGATE1 PGND VOUT1 FB1 ENTRIP1 EN VREG5 VIN VOUT REF - + PGOOD © Copyright 2012 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 TONSEL SKIPSEL VREG5 SMPS1 PWM Buck PWM Buck Controller Controller Power-On ...
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... There is an internal 10uA current source © Copyright 2012 Richtek Technology Corporation. All rights reserved. DS8205A/B/C-06 July 2012 RT8205A/B/C from VREG5 to ENTRIP2. The logic current limit threshold is default to 200mV value if ENTRIP2 is higher than VREG5-1V. VOUT2 (Pin 7) SMPS2 Output Voltage-Sense Input. Connect to the SMPS2 output ...
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... RT8205A/B/C GND [Pin 15 (RT8205A), Exposed Pad (25)] Analog Ground for SMPS controller. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. PGND (Pin 15) (RT8205B/C) Power Ground for SMPS controller. Connect PGND externally to the underside of the exposed pad. ...
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... Input Voltage, VIN -------------------------------------------------------------------------------------------- 6V to 25V Junction Temperature Range ------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range ------------------------------------------------------------------------------- −40°C to 85°C © Copyright 2012 Richtek Technology Corporation. All rights reserved. DS8205A/B/C-06 July 2012 (Note 1) (Note registered trademark of Richtek Technology Corporation. RT8205A/B/C www.richtek.com continued ...
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... RT8205A/B/C Electrical Characteristics (V = 12V 5V, ENTRIP1 = ENTRIP2 = 2V, No Load on VREG5, VREG3, VOUT1, VOUT2 and REF otherwise specified) Parameter Symbol Input Supply VIN Standby Supply I VIN_SBY Current VIN Shutdown Supply I VIN_SHDH Current Quiescent Power Consumption SMPS Output and FB Voltage VOUT1 Output Voltage in ...
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... Reference, Falling Edge, Hysteresis = 1% Falling Edge, 50mV Overdrive High State, Forced to 5. 4mA SINK FBx with Respect to Internal V FB_OVP Reference FBx with Respect to Internal Reference t From ENTRIPx Enable SHDN_UVP T SHDN RT8205A/B/C Min Typ = 0. =1V 90 100 =2V 180 200 -- 3 < 25V, IN 4.8 5 < 25V ...
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... RT8205A/B/C Parameter VOUT Discharge VOUTx Discharge Current Logic Input FB1/FB2 Input Voltage SKIPSEL Input Voltage ENTRIPx Input Voltage EN Threshold Logic-High Voltage Logic-Low TONSEL Setting Voltage Input Leakage Current Internal BOOT Switch Internal Boost Charging Switch On-Resistance Power MOSFET Drivers UGATEx Driver Sink/Source ...
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... Richtek Technology Corporation. All rights reserved. DS8205A/B/C-06 July 2012 Ultrasonic Mode , IN 0 Ultrasonic Mode , IN 0 Ultrasonic Mode PWM Mode , IN 0 RT8205A/B/C V Output Efficiency vs. Load Current OUT2 100 90 80 DEM Mode 70 60 Ultrasonic Mode 50 PWM Mode 8V, TONSEL = GND ENTRIP1 = GND, ENTRIP2 = 0.91V 0 0 ...
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... RT8205A/B/C V Output Switching Frequency vs. Load Current OUT1 250 V = 8V, TONSEL = GND 225 ENTRIP1 = 0.91V, ENTRIP2 = GND 200 PWM Mode 175 150 125 100 75 50 Ultrasonic Mode 25 0 0.001 0.01 0.1 Load Current (A) V Output Switching Frequency vs. Load Current OUT1 250 V = 12V, TONSEL = GND ...
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... Richtek Technology Corporation. All rights reserved. DS8205A/B/C-06 July 2012 , IN 0 RT8205A/B/C V Output Voltage vs. Load Current OUT2 3.378 V = 12V, TONSEL = GND ENTRIP1 = GND, ENTRIP2 = 0.91V 3.372 3.366 Ultrasonic Mode 3.360 3.354 DEM Mode 3.348 3.342 PWM Mode 3.336 3 ...
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... RT8205A/B/C Standby Input Current vs. Input Voltage 252 No Load ENTRIP1 = ENTRIP2 = GND IN 250 248 246 244 242 240 Input Voltage (V) V vs. Temperature REF 2.011 2.008 2.005 2.002 1.999 1.996 1.993 V = 12V, ENTRIP1 = ENTRIP2 = GND TONSEL = GND IN 1.990 -40 -25 -10 ...
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... ENTRIP1 (1V/Div) ENTRIP2 (1V/Div OUT1_ac (50mV/Div) Inductor Current (5A/Div) UGATE1 (20V/Div) LGATE1 (10V/Div) RT8205A/B/C V Start Up OUT2 No Load 12V, TONSEL = GND OUT2 ENTRIP1 = ENTRIP2 = 0.91V Time (400μs/Div) V Delay Start OUT1 No Load 12V, TONSEL = GND ...
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... RT8205A/B/C V PWM Mode Load Transient Response OUT2 V = 12V, TONSEL = GND SKIPSEL = GND, I OUT2 V OUT2_ac (50mV/Div) Inductor Current (5A/Div) UGATE2 (20V/Div) LGATE2 (10V/Div) Time (20μs/Div) No Load 12V, TONSEL = GND OUT1 (5V/Div) V OUT2 (2V/Div) PGOOD (5V/Div) Time (4ms/Div) © ...
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... PWM schemes. The DRV modulator is specifically designed to have better noise immunity for such a dual output application. The RT8205A/ B/C includes 5V (VREG5) and 3.3V (VREG3) linear regulators. VREG5 linear regulator can step down the battery voltage to supply both internal circuitry and gate drivers ...
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... REF VREG5 or 500 VREG3 Operation Mode Selection (SKIPSEL) The RT8205A/B/C supports three operation modes : Diode- Emulation Mode, Ultrasonic Mode, and Forced-CCM Mode. Diode-Emulation Mode (SKIPSEL = REF) In Diode-Emulation mode, The RT8205A/B/C automatically reduces switching frequency at light-load conditions to maintain high efficiency. This reduction of frequency is achieved smoothly and without increase of V load regulation ...
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... The benefit of forced- IN The RT8205A/B/C uses the on-resistance of the synchronous rectifier as the current-sense element. Use the worse-case maximum value for R MOSFET datasheet, and add a margin of 0.5%/°C for the rise in R The R the over current threshold ...
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... RT8205A/B/C D4 when LGATE1 switched to high. So − OUT1 LGATE1 Where V is the peak voltage of LGATE1 driver and is LGATE1 equal to the VREG5 the forward diode dropped D across the Schottky. LG1_CP in the RT8205B (Figure 3) can be used as clock signal for charge pump circuit to generate approximately ...
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... This activates the low-side MOSFET switch, which rapidly discharges the output capacitor and pulls the input voltage downward. RT8205A/B/C is latched once OVP is triggered and can only be released by EN power-on reset. There is 10us delay built into the over voltage protection circuit to prevent false transition ...
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... RT8205A/B/C Output Voltage Setting (FBx) Connect FBx directly to GND or VREG5 to enable the fixed, SMPS output voltages (3.3V and 5V). Connect a resistor voltage-divider at the FBx between the VOUTx and GND to adjust the respective output voltage between 2V and 5.5V (Figure 6). Choose approximately 10kΩ, and solve for R1 using the equation : ⎡ ...
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... For recommended operating conditions specification, the maximum junction temperature is 125°C. The junction to ambient thermal resistance θ WQFN-24L 4x4 packages, the thermal resistance θ 52°C/W on the standard JEDEC 51-7 four layers thermal RT8205A/B θ D(MAX) J(MAX) ...
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... Layout is very important in high frequency switching converter design. If the IC is designed improperly, the PCB could radiate excessive noise and contribute to the converter instability. Certain points must be considered before starting a layout using the RT8205A/B/C. and thermal J(MAX) Four Layers PCB WQFN-24L 4x4 ...
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... High (after REF powers up) On Low (after REF powers up) On High (after ENTRIP1 (after REF is high without 60us) powers up) On High (after REF powers up) RT8205A/B/C Comment VREG3 SMPS1 Off Off On (after REF Off powers up) On (after REF Off powers up (after REF ...
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... RT8205A/B/C Outline Dimension Symbol 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 ...