rt9245b Richtek Technology Corporation, rt9245b Datasheet
rt9245b
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rt9245b Summary of contents
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... General Description RT9245B is a multi-phase buck DC/DC controller integrated with all control functions for AMD K8 CPU. The RT9245B could be operated with buck switching stages operating in interleaved phase set automatically. The multiphase architecture provides high output current while maintaining low power dissipation on power devices and low stress on input and output capacitors ...
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... RT9245B Typical Application Circuit + + + www.richtek.com DS9245B-02 March 2007 ...
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... PWM outputs for each driven channel. Connect these pins to the PWM input of the MOSFET driver. For systems which use 3 channels, connect PWM4 high. Two channel systems connect PWM3 high. VCC (Pin 28) IC power supply. Connect this pin supply. RT9245B www.richtek.com 3 ...
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... RT9245B Function Block Diagram www.richtek.com 4 DS9245B-02 March 2007 ...
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... RT9245B Nominal Output Voltage DACOUT VID0 0 1.5500 1 1.5250 0 1.5000 1 1.4750 0 1.4500 1 1.4250 0 1.4000 1 1.3750 0 1.3500 1 1.3250 0 1.3000 1 1.2750 0 1.2500 1 1.2250 0 1.2000 1 1.1750 0 1.1500 1 1 ...
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... RT9245B VID5 VID4 VID3 Note: ( Connected to GND ( Open www.richtek.com 6 Table 1 ...
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... CCRTH CC V CCHYS V Enable DVDTP V DVDHYS 20k OSC RT f OSC_ADJ 20k OSC 20k DAC V DAC V < 1V DAC V ILDAC V IHDAC RT9245B + 0.3V CC 10% Min Typ Max Units -- 4.0 4.2 4.5 V 0.2 0 0.94 1.0 1. 170 200 230 kHz 50 -- 400 kHz -- 1 ...
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... RT9245B Parameter DAC (VID0-VID5) pull up resistor DAC Pull Up Voltage VOSS Pin Voltage Error Amplifier DC Gain Gain-Bandwidth Product Slew Rate Current Sense GM Amplifier CSN Full Scale Source Current CSN Current for OCP Protection Over-Voltage Trip ( DAC IMAX Voltage Power Good Output Low Voltage Note 1. Stresses listed as the above “ ...
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... SS PWM UGATE CH3:(20V/Div) CH4:(10V/Div) LGATE Time (10ms/Div) DS9245B-02 March 2007 (kW) ADJ UGATE LGATE CH3:(50mV/Div) CH4:(20A/Div 60A OUT V RT9245B PWM vs 16k 0 (V) COMP Power-Off @ I PWM COMP Time (10 s/Div) ...
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... RT9245B DVID at Rising (500mV/Div) V CORE VID5 (2V/Div) Time (50 s/Div) Transient Response Time (5ms/Div) www.richtek.com 10 V CORE (500mV/Div) VID5 (2V/Div) (20mV/Div) V CORE (20mV/Div) DVID at Falling Time (50 s/Div) Transient Falling Time (500ns/Div) DS9245B-02 March 2007 ...
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... GND or left float if the channel is unused. For example, for 3-Channel application, connect PWM4 high. Current Sensing Setting into the resistor R X ADJ RT9245B senses the current flowing through inductor via its DCR for channel current balance and droop tuning ADJ ...
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... V C programmable over current trip point. OCP comparator + CSN compares each inductor current with this reference current CSN RT9245B uses hiccup mode to eliminate fault detection 1k of OCP or reduce output current when output is shorted to ground 100 125 150 Time Sharing of GM ...
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... DCR R2 V DCR )/R times current than other phases 0.3uH 0.6m 470 1uF 470 Figure 10. GM4 Setting for current ratio function I L 0.3uH 0.6m 470 1uF Figure 11. GM1~3 Setting for current ratio function RT9245B DCR www.richtek.com 13 ...
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... Referring to Figure 15 100 I X (A) where I make sure RT9245B could sense the inductor current, right hand side of Equation (1) should always be positive CSN R Since R could be simplified as : and consequently X R Figure 14 shows that dead zone of load line at light load is eliminated by applying this technique ...
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... VID on the Fly With external pull up resistors tied to VID pins, RT9245B converters different VID codes from CPU into output voltage. Figure 16 and Figure 17 show the waveforms of VID on the fly function. VID on the Fly (Falling) PWM V CORE V FB CH1:(5V/Div) CH2:(500mV/Div) ...
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... MOSFET and low side MOSFET. V will fall slowly to avoid negative V OUT typical waveform is shown in Figure 22. www.richtek.com 16 If the fault condition is OV, V low immediately also. RT9245B will try to turn on low and 12V CC IN side MOSFET and turn off high side MOSFET 12V is not ready CC IN fall quickly to protect CPU from high voltage ...
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... PGOOD V (SS) V OUT OV Figure 23. Waveform for OV Error Amplifier Characteristic For fast response of converter to meet stringent output current transient response, RT9245B provides large slew rate capability and high gain-bandwidth performance. EA Falling Slew Rate V FB CH1:(500mV/Div) V COMP CH2:(2V/Div) Time (250ns/Div) Figure 24. EA Rising Transient with 10pF Loading; Slew ...
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... RT9245B 0dB 180 Figure 27. EA Frequency Response with closed loop gain set at 0db to observe gain-bandwidth product; -3dB at Design Procedure Suggestion a.Output filter pole and zero (Inductor, output capacitor value & ESR). b.Error amplifier compensation & sawtooth wave amp- litude (compensation network). ...
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... For most application cases, 0 good engineering value. Figure 29. The Frequency Response with No Load C2 5.6pF C3 680pF C1 RB2 15k 2.7nF RB1 - EA 1.5k + Figure 28. Type 3 compensation network DCR IMAX IMAX COMMON 1.690V 1 40A 1.39m R 3 330 IMAX = 14k IMAX RT9245B www.richtek.com 19 ...
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... RT9245B www.richtek.com 20 Figure 30. The Frequency Response with Middle Load Figure 31. The Frequency Response with Heavy Load DS9245B-02 March 2007 ...
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... MOSFET driver should be closed to MOSFET. 4. The compensation, bypass and other function setting components should be near the IC and away from the noisy power path DS9245B-02 March 2007 SW1 IN SW2 Figure 32. Power Stage Ripple Current Path L1 V OUT C OUT L2 RT9245B R L www.richtek.com 21 ...
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... C BOOT CORE C OUT C IN For Thermal Couple Figure 33. Layout Consideration Figure 34. Layout of power stage PWM VCC RT VOSS COMP SGND RT9245B R CSN R CSN FB R CSPx ADJ GND DS9245B-02 March 2007 + Next Locate next to FB Pin ...
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... TSSOP Plastic Package 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 RT9245B L A2 Dimensions In Inches Min Max 0.033 0.047 0.002 0.006 0.031 ...