RT9204_07 RICHTEK | Alldatasheet
Document overview
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Technical content
Features
l 0.8V Internal Reference l Voltage Mode PWM Control l Fast Transient Response l Fixed 600kHz Oscillator Frequency l Full 0 to 100% Duty Cycle l Internal Soft Start l Internal PWM Loop Compensation l RoHS Compliant and 100% Lead (Pb)-Free Pin Configurations
Applications
l Motherboard Power Regulation for Computers l Subsystems Power Supplies l Cable Modems, Set Top Box, and DSL Modems l DSP and Core Communications Processor Supplies l Memory Power Supplies l Personal Computer Peripherals l Industrial Power Supplies l 5V-Input DC-DC Regulators l Low Voltage Distributed Power Supplies Dual Regulators - Standard Buck PWM DC-DC and Linear Controller
Ordering Information
The RT9204/A is a dual power controllers designed for high performance graphics cards and computer applications. The IC integrates a standard buck controller, a linear regulator driver and protection functions into a small 8-pin package. The RT9204/A uses an internal compensated voltage mode PWM control for simple application design. An internal 0.8V reference allows the output voltage to be precisely regulated to low voltage requirement. A fixed 600kHz oscillator reduce the component size for saving board area. The RT9204/A protects the converter and regulator by monitoring the output under voltage. (TOP VIEW) SOP-8 GND VCC DRV FBL FB SD BOOT UGATE 4 5 8Note : RichTek Pb-free and Green products are : }RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. }Suitable for use in SnPb or Pb-free soldering processes. }100%matte tin (Sn) plating. RT9204/A Package Type S : SOP-8 Operating Temperature Range P : Pb Free with Commercial Standard G : Green (Halogen Free with Commer- cial Standard) UVP : Hiccup Mode UVP : Latch Mode
DS9204/A-08 March 2007www.richtek.com Typical Application Circuit VCC DRV UGATE BOOT GND SD RT9204/A FB 100 220uF VOUT2 1.6V 1uF 3.3V 2SD1802 C3 0.1uF BAT54A 250 120 10nF FBL 100 5uH 1000uF 2.5V VOUT1 MU C2 1uF 470uF VAUX SS34 VCC DRV UGATE BOOT GND SD RT9204/A FB 100 220uF VOUT2 1.6V 3.3V 2SD5706 250 120 10nF FBL 100 5uH 1000uF 2.5V VOUT1 MU C2 1uF 470uF 12V VAUX SS34 Suggest use Transistor 1uF 1uF 5V Figure1. RT9204/A powered from 5V only Figure2. RT9204/A powered from 12V
DS9204/A-08 March 2007www.richtek.com Function Block Diagram GND VCC RT9203/A BOOT CVCC 1uF CBOOT 0.1uF COUT 1000uF L 5uH MU D G S Diode CIN1 1uF CIN2 470uF GND Return Layout Placement Layout Notes 1. Put C 1 & C2 to be near the MU drain and ML source nodes. 2. Put RT9204/A to be near the C OUT 3. Put C BOOT as close as to BOOT pin 4. Put C VCC as close as to VCC pin 0.8 Reference Power on Reset Soft Start OVP UVP -35dB 0.8V 0.5V Error Amplifier PWM 600kHz Oscillator Control Logic 6.0V Regulation GND FB VCC BOOT UGATE UVP +SS LDODRV FBL
DS9204/A-08 March 2007www.richtek.com Functional Pin Description GND (Pin 1) Signal and power ground for the IC. All voltage levels are measured with respect to this pin. VCC (Pin 2) This is the main bias supply for the RT9204/A. This pin also provides the gate bias charge for the lower MOSFETs gate. The voltage at this pin monitored for power-on reset (POR) purpose. This pin is also the internal 6.0V regulator output powered from BOOT pin when BOOT pin is directly powered from ATX 12V. DRV (Pin 3) This pin is linear regulator output driver. Connect to external bypass NPN transistor base or NMOSFET gate terminal. FBL (Pin 4) This pin is connected to the linear regulator output divider. This pin also connects to internal linear regulator error amplifier inverting input and protection monitor. FB (Pin 5) This pin is connected to the PWM converter's output divider. This pin also connects to internal PWM error amplifier inverting input and protection monitor. SD (Pin 6) Active low design with a 40 µA pull low current source. Pull this pin to VCC to shutdown both PWM and linear regulator. BOOT (Pin 7) This pin provides ground referenced bias voltage to the upper MOSFET driver. A bootstrap circuit is used to create a voltage suitable to drive a logic-level N-Channel MOSFET when operating at a single 5V power supply. This pin also could be powered from ATX 12V, in this situation, an internal 6.0V regulator will supply to VCC pin for internal voltage bias. UGATE (Pin 8) Connect UGATE pin to the PWM converter's upper MOSFET gate. This pin provides the gate drive for the upper MOSFET.
DS9204/A-08 March 2007www.richtek.com Absolute Maximum Ratings l Power Dissipation, PD @ TA = 25°C l Package Thermal Resistance CAUTION: Stresses beyond the ratings specified in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
Electrical Characteristics
(VCC = 5V, T A = 25 °C, Unless otherwise specified.) Parameter Symbol Test Conditions Min Typ Max Units VCC Supply Current Nominal Supply Current ICC UGATE, LGATE open -- 3 -- mA VCC Regulated Voltage VCC VBOOT=12V -- 6 -- V Power-On Reset Rising VCC Threshold 3.75 4.1 4.35 V VCC Threshold Hysteresis -- 0.5 -- V Reference Reference Voltage Both FB & FBL 0.784 0.8 0.816 V Oscillator Free Running Frequency 550 600 650 kHz Ramp Amplitude Δ VOSC -- 1.75 -- VP-P PWM Error Amplifier DC Gain -- 35 -- dB PWM Controller Gate Driver Upper Drive Source RUGATE VBOOT = 12V; VBOOT - VUGATE = 1V -- 7 -- Ω Upper Drive Sink RUGATE VUGATE = 1V -- 5 -- Ω Linear Regulator DRV Driver Source VDRV = 2V 100 -- -- mA To be continued
DS9204/A-08 March 2007www.richtek.com Parameter Symbol Test Conditions Min Typ Max Units Protection FB Over-Voltage Trip FB Rising -- 1 -- V FB & FBL Under-Voltage Trip FB & FBL Falling -- 0.5 -- V Soft-Start Interval -- 1 -- ms SD Pin Threshold VCC = 5V -- 1.5 -- V SD pin Sink Current VCC = 5V -- 40 -- µA
DS9204/A-08 March 2007www.richtek.com Typical Operating Characteristics Load Transient Time (5us/Div) VCC = 5V VOUT = 2.2V COUT = 3000uF VOUT UGATE Power On Time (1ms/Div) VCC = 5V VOUT = 2.2V VCC VOUT1 VOUT2 Short Hiccup Time (2ms/Div) VCC = 5V VOUT = 2.2V VOUT UGATE RT9204A Load Transient Time (5us/Div) VCC = 5V VOUT = 2.2V COUT = 3000uF VOUT UGATE Power Off Time (50ms/Div) VCC = 5VVCC VOUT1 VOUT2 Short Hiccup (Latch Mode) Time (5ms/Div) VCC = 5V VOUT = 2.2V VOUT UGATE RT9204
DS9204/A-08 March 2007www.richtek.com Reference vs. Temperature 0.796 0.797 0.798 0.799 0.800 0.801 0.802 0.803 -50050100150 Temperature Reference (V) (°C) Oscillator Frequency vs. Temperature 270 275 280 285 290 295 300 305 310 315 -50050100150 Temperature Frequency (kHz) A (°C) POR (Rising/Falling) vs. Temperature 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 -50050100150 Temperature POR (V) Rising Falling (°C)
DS9204/A-08 March 2007www.richtek.com The power components and the PWM controller should be placed firstly. Place the input capacitors, especially the high-frequency ceramic decoupling capacitors, close to the power switches. Place the output inductor and output capacitors between the MOSFETs and the load. Also locate the PWM controller near by MOSFETs. A multi-layer printed circuit board is recommended. Figure 13. shows the connections of the critical components in the converter. Note that the capacitors CIN and COUT each of them represents numerous physical capacitors. Use a dedicated grounding plane and use vias to ground all critical components to this layer. Apply another solid layer as a power plane and cut this plane into smaller islands of common voltage levels. The power plane should support the input power and output power nodes. Use copper filled polygons on the top and bottom circuit layers for the PHASE node, but it is not necessary to oversize this particular island. Since the PHASE node is subjected to very high dV/dt voltages, the stray capacitance formed between these island and the surrounding circuitry will tend to couple switching noise. Use the remaining printed circuit layers for small signal routing. The PCB traces between the PWM controller and the gate of MOSFET and also the traces connecting source of MOSFETs should be sized to carry 2A peak currents. Figure 13 LOAD VCC GND RT9204/A FB UGATE ILIQ1 VOUT IQ2 GND
DS9204/A-08 March 2007www.richtek.com Richtek Technology Corporation Headquarter 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Richtek Technology Corporation Taipei Office (Marketing) 8F, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek.com Outline Dimension A BJ F H M C D I 8-Lead SOP Plastic Package Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 4.801 5.004 0.189 0.197 B 3.810 3.988 0.150 0.157 C 1.346 1.753 0.053 0.069 D 0.330 0.508 0.013 0.020 F 1.194 1.346 0.047 0.053 H 0.170 0.254 0.007 0.010 I 0.050 0.254 0.002 0.010 J 5.791 6.200 0.228 0.244 M 0.400 1.270 0.016 0.050