PM6641TR STMicroelectronics, PM6641TR Datasheet

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... UMPC and portable equipment ■ Handheld and PDAs Table 1. Device summary Order codes PM6641 PM6641TR May 2009 Monolithic VR for chipset and DDR2/3 supply for ultra-mobile PC (UMPC) applications Description The PM6641 is a monolithic voltage regulator module specifically designed to supply DDR2/3 memory and chipset in ultra-mobile PC and real estate constrained portable systems ...

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Contents Contents 1 Typical application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

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PM6641 7.11.1 7.11.2 7.11.3 7.11.4 8 Components selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

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Typical application circuit 1 Typical application circuit Figure 1. Application circuit 4/47 VTTREF SET_SWF EN_VTT (S3) VTTFB VTT VTTGND AVCC VCC LDOIN Doc ID 13510 Rev 3 PM6641 VIN_1S05 VSW_1S05 VFB_1S05 SGND_1S05 SS_1S05 SET_PH1 COMP_1S05 EN_1S05 (S5) EN_1S8 PG_1S05 PG_1S8 ...

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PM6641 2 Pin settings 2.1 Connections Figure 2. Pin connection (through top view) SET_SWF VOUT_1S8 SGND_1S8 SGND_1S8 VSW_1S8 VSW_1S8 COMP_1S8 AGND CSNS PM6641 VIN_1S8 VIN_1S8 VFB_1S8 Doc ID 13510 Rev 3 Pin settings EN_VTT (S3) EN_1S5 EN_1S05 VIN_1S5 VSW_1S5 VSW_1S5 ...

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Pin settings 2.2 Pin description Table 2. Pin functions n° Pin 1 AGND 2 SET_SWF 3 VOUT_1S8 4 CSNS 5 SGND_1S8 6 SGND_1S8 7 VSW_1S8 8 VSW_1S8 9 VIN_1S8 10 VIN_1S8 11 VFB_1S8 12 COMP_1S8 13 SS_1S8 14 SS_1S05 15 ...

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PM6641 Table 2. Pin functions (continued) n° Pin 26 SS_1S5 27 COMP_1S5 28 VFB_1S5 29 SGND_1S5 30 SGND_1S5 31 VSW_1S5 32 VSW_1S5 33 VIN_1S5 34 EN_1S05 35 EN_1S5 36 EN_VTT 37 EN_1S8 38 AGND 39 SET_PH1 40 AGND 41 AVCC ...

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Electrical data 3 Electrical data 3.1 Maximum rating Table 3. Absolute maximum ratings Symbol V VIN_x to SGND_x VIN V VCC to AGND or SGND_x VCC V AVCC to AGND or SGND_x AVCC AGND to SGND_x VTTGND to SGND_x VSW_x ...

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PM6641 3.3 Recommended operating conditions Table 5. Recommended operating conditions Symbol V AVCC voltage range AVCC V VCC IC supply voltage VCC V VIN_x input voltage range IN Parameter Doc ID 13510 Rev 3 Electrical data Values Unit Min Typ ...

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Electrical characteristics 4 Electrical characteristics ° °C, AVCC = 5 V, VCC = 5 V, VIN_x = 3.3 V and LDOIN connected to 1 output if not otherwise specified Table 6. Electrical characteristics ...

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PM6641 Table 6. Electrical characteristics (continued) Symbol Parameter Thermal shutdown Thermal shutdown threshold T SHDN Thermal shutdown hysteresis Switching node – chipset 1.5 V rail t Minimum on-time Onmin R High side PMOS Ron DSon,HS R Low side NMOS Ron ...

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Electrical characteristics Table 6. Electrical characteristics (continued) Symbol Parameter LS turn-on VFB_1SX threshold with internal divider LS turn-on VFB_1SX threshold with external divider Power management section – chipset 1.05 V rail EN_1S05 turn-off level EN_1S05 turn-on level Switching node – ...

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PM6641 Table 6. Electrical characteristics (continued) Symbol Parameter V LDO section – DDR2/3 rails TT Power Good upper threshold PG_VTT_TH Power Good lower threshold LDO input bias current in full- I LDOIN,ON ON state LDO input bias current in I ...

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Typical operating characteristics 5 Typical operating characteristics Figure 3. VDDQ and VTT soft-start without load Figure 5. 1V5 soft-start without load Figure 7. 1V05 soft-start without load 14/47 Figure 4. VDDQ and VTT soft-start with AVG load Figure 6. 1V5 ...

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PM6641 Figure 9. VDDQ output ripple and phase @ AVG current Figure 11. 1V5 output ripple and phase @ AVG current Figure 13. SW reg. efficiency @ 600 kHz ...

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Typical operating characteristics Figure 15. 1.5 V load regulation 1,536 1,534 1,532 1,530 1,528 1,526 1,524 1,522 0,00 0,50 1,00 1,50 Load Current [ A] Figure 17. VDDQ (1.8 V) load transient: 0-AVG Figure 18. VTT load transient ...

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PM6641 Figure 21. VDDQ e VTT soft-end with DSCG = AVCC Figure 23. Current limit Figure 25. Output OV (1V5 Note: All the above measures and screen captures are based on PM6641EVAL demonstration board. Refer to PM6641 demonstration ...

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Block diagram 6 Block diagram Figure 27. Functional and block diagram PG_1S8 PG_1S8 VTTREF VTTREF VTTFB VTTFB LDOIN LDOIN VTT VTT VTTGND VTTGND VOUT_1S8 VOUT_1S8 SET_PH1 SET_PH1 SET_SWF SET_SWF VIN_1S05 VIN_1S05 SW_1S05 SW_1S05 SGND_1S05 SGND_1S05 COMP_1S05 COMP_1S05 VFB_1S05 VFB_1S05 SS_1S05 ...

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PM6641 7 Device description The PM6641 is an integrated voltage regulator module designed to supply DDR2/3 memory and chipset I/O in real estate constrained portable equipment and ultra-mobile PCs. The device consists of three buck regulators (two for chipset supply ...

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Device description 7.1 Memory supply The DDR2/3 section of PM6641 is based on the VDDQ rail, the VTT termination rail and the VTTREF reference voltage buffer. The VDDQ rail is provided by a step-down switching regulator whose output voltage, by ...

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PM6641 the loop voltage reference is increased linearly from zero long time ( couple of milliseconds) (see When the EN_1S8 pin goes low, the VDDQ rail output capacitor is discharged through internal discharge ...

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Device description 7.1.4 S3 and S5 power management pins According to DDR2/3 memories supply requirements, the PM6641 can manage all system states just connecting EN_VTT – EN_1S8 pins to their respective sleep-mode signals in the notebook’s motherboard: ...

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PM6641 current mode loop to avoid sub-harmonic instability with duty cycle greater than 50%, is internally implemented and no further external components are required. The chipset supply is able to source the following average and peak currents, assuming 1 A ...

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Device description 7.3 SW regulators control loop The PM6641 switching regulators are buck converters employing a constant frequency, peak current mode PWM control loop, as shown in the following figure: Figure 28. SW regulator control loop In the current mode ...

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PM6641 In order to obtain the typical integrative loop transfer function the signal stag e must compensate for the power stage pole (due to the output capacitor and the load) and zero (above the loop bandwidth if ceramic output capacitors ...

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Device description 7.4 SW regulators pulse skipping and PWM mode In order to enhance the light load efficiency each switching regulator enters the pulse skipping algorithm when the output current sourced is too low. The threshold load current which allows ...

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PM6641 7.5 Output voltage divider PM6641 switching regulators are adjustable voltage converters. If the feedback pin (VFB_1S8, VFB_1S5, VFB_1S05 respectively belonging to VDDQ (1.8 V), 1.5 V, 1.05 V rail) is directly tied to the rail output capacitor the internal ...

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Device description 7.6 Outputs soft-start The soft-start function of each switching regulator is achieved by ramping up the SS pin voltage with a constant slew rate dV/dt. When the switching section is enabled (EN high), the SS pin constant current ...

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PM6641 7.7 Outputs soft-end When the switching regulator enable pin (EN_1S8 for the VDDQ section, EN_1S5 and EN_1S05 for chipset sections) goes down or when UV or thermal protections are detected, the switching regulator output capacitor is actively discharged through ...

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Device description 7.9 Phase management When all the three switching regulators high side MOSFETs are turned on simultaneously the input root mean square (RMS) current could rise up to very high values, increasing the system losses and inducing external components ...

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PM6641 The synchronous mode of operation provides the following total input current: Equation 8 whereas by shifting the three regulator turn on pulses of 120 deg the resulting total input current is given by Equation 9 I CIN 3 ≅ ...

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Device description where VREF = 0.9V is the constant voltage forced by CSNS pin, R connected between CSNS and AGND, α is the coefficient that collects the MOS current sensing scaling factor and other design parameters and I The following ...

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PM6641 7.11 Fault management PM6641 has been conceived to constantly monitor the rails output voltage. In order to protect itself from failure and the load from damage, the device is able to: ● Limit the power MOSFETs current ● Detect ...

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Device description 7.11.3 Thermal shutdown If the device temperature exceeds 150 °C, a thermal protection is triggered consequence, the output soft end takes place for all the outputs of the PM6641 (VDDQ rail (1.8 V), VTT, VTTREF, 1.5 ...

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PM6641 8 Components selection The PM6641 switching regulator sections are buck converters employing a constant frequency, current mode PWM current loop (see page 24 section for details). The duty-cycle of the buck converter is, in steady-state conditions, given by Equation ...

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Components selection Once the inductor value is determined, the inductor current ripple is then recalculated: Equation 13 The next step is the computation of the maximum RMS inductor current: Equation 14 The inductor must have an RMS current greater than ...

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PM6641 The losses due to the input capacitor are thus maximized when the duty-cycle is 0.5: Equation 18 The input capacitor should be selected with a RMS rated current higher than I Tantalum capacitors are good in term of low ...

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Components selection If ceramic capacitors are used, the output voltage ripple due to inductor current ripple is negligible. Then the inductance could be smaller, reducing the size of the choke. In this case it is important that output capacitor can ...

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PM6641 From the definition of cross-over frequency, the value of the compensation resistor is derived: Equation 25 A good choice for the cross-over frequency is to assign f The fixed parameters g feedback divider factor (α) is application dependant (see ...

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Components selection 8.5 Layout guidelines Each signal is referred to AGND, the analog ground typical 4-layers PCB one internal layer should be dedicated to this common ground. The IC thermal pad must be connected to AGND plane through ...

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PM6641 9 Application examples The following application examples are typical or customized applications. Each example has been tested and evaluated and the schematic and BOM are available for reference design. 9.1 UMPC DDR2 and chipset power supply Figure 34. System ...

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Application examples The default switching frequency has been selected (750 kHz) and the tracking discharge has been enabled in agreement with DDR2 JEDEC specifications. No external resistor dividers are required for these output voltage levels. The allowed inductor current ripple ...

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PM6641 Table 13. BOM suggested components for DDR2 and chipset power supply Qty Component Description 1 C1 Ceramic X5R, 10% C2, C3, C4, 4 Ceramic X5R, 10% C12 C6, C7, C9, 5 Ceramic X5R, ...

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Package mechanical data 10 Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ® ECOPACK packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available ...

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PM6641 Figure 36. VFQFPN-48 (7x7x1.0 mm) package drawings Doc ID 13510 Rev 3 Package mechanical data 45/47 ...

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Revision history 11 Revision history Table 15. Document revision history Date 16-May-2007 16-Jan-2008 04-May-2009 46/47 Revision 1 Initial release Document status promoted from preliminary data to datasheet. Updated: Table 2 on page 2 Chapter 7: Device description on page Added: ...

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