PM6680TR STMicroelectronics, PM6680TR Datasheet
PM6680TR
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PM6680TR
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PM6680TR Summary of contents
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... Mobile system power supply ■ 3-4 cells Li+ battery powered devices Table 1. Device summary Order codes PM6680 PM6680TR January 2008 for notebook system power Description PM6680 is a dual step-down controller specifically designed to provide extremely high efficiency conversion, with lossless current sensing technique. The constant on-time ...
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Contents Contents 1 Simplified application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 Electrical ...
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PM6680 7.13 Design guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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List of figures List of figures Figure 1. Simplified application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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PM6680 List of tables Table 1. Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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Simplified application schematic 1 Simplified application schematic Figure 1. Simplified application schematic 6/49 VIN 19 LDO5 18 VCC 31 PM6680 FSEL 3 SKIP 24 VREF 32 EN1 25 EN2 4 ...
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PM6680 2 Electrical data 2.1 Maximum rating Table 2. Absolute maximum ratings V5SW, LDO5 to PGND VIN to PGND HGATEx and BOOTx, to PHASEx PHASEx to PGND CSENSEx , to PGND CSENSEx to BOOTx LGATEx to PGND FBx, COMPx, SKIP, ...
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Pin settings 3 Pin settings 3.1 Connections Figure 2. Pin connection (Through top view) 8/49 PM6680 PM6680 ...
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PM6680 3.2 Functions Table 4. Pin functions N° Pin 1 SGND1 2 COMP2 3 FSEL 4 EN2 5 SHDN FB2 8 OUT2 9 BOOT2 10 HGATE2 11 PHASE2 12 CSENSE2 13 LGATE2 14 PGND 15 LGATE1 Signal ...
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Pin settings Table 4. Pin functions (continued) N° Pin 16 SGND2 17 V5SW 18 LDO5 19 VIN 20 CSENSE1 21 PHASE1 22 HGATE1 23 BOOT1 24 SKIP 25 EN1 26 PGOOD1 27 PGOOD2 28 FB1 10/49 Signal ground for analog ...
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PM6680 Table 4. Pin functions (continued) N° Pin 29 OUT1 30 COMP1 31 VCC 32 VREF Output voltage sense for the switching section 1.This pin must be directly connected to the output voltage of the switching section. DC voltage error ...
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Electrical characteristics 4 Electrical characteristics Table 5. Electrical characteristics ° °C, unless otherwise specified IN A Symbol Parameter Supply section VIN Input voltage range Vcc IC supply voltage Turn-on voltage threshold ...
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PM6680 Table 5. Electrical characteristics (continued ° °C, unless otherwise specified IN A Symbol Parameter On time pulse width Ton On time duration OFF time T Minimum off time OFFMIN Voltage ...
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Electrical characteristics Table 5. Electrical characteristics (continued ° °C, unless otherwise specified IN A Symbol Parameter High and low gate drivers HGATE driver on-resistance LGATE driver on-resistance PGOOD pins UVP/OVP protections ...
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PM6680 5 Typical operating characteristics FSEL = GND (200/300 kHz), SKIP = GND (skip mode), V5SW = V5SW = EXT5V (external 5 V power supply connected), input voltage VIN = 12 V, SHDN, EN1 and EN2 high, OUT1 = 1.5 ...
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Typical operating characteristics Figure 7. No-audible skip no load battery current vs input voltage Figure 9. Shutdown mode input battery current vs input voltage Figure 11. 1.05 V switching frequency vs load current 16/49 Figure 8. Stand-by mode input battery ...
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PM6680 Figure 13. 1.5 V voltage regulation vs load current Figure 15. Voltage reference vs load current Figure 17. 1.5 V load transient Typical operating characteristics Figure 14. 1.05 V voltage regulation vs load current Figure 16. OUT1, OUT2 and ...
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Typical operating characteristics Figure 19. 1.5 V soft start (0.25 Figure 21. 1.5 V soft end (No load) Figure 23. 1.5 V soft end (1 18/49 Ω load) Figure 20. 1.05 V soft start (0.175 Figure 22. 1.05 V soft ...
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PM6680 Figure 25. 1.5 V no-audible skip mode Typical operating characteristics Figure 26. 1.05 V no-audible skip mode 19/49 ...
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Block diagram 6 Block diagram Figure 27. Functional block diagram VCC VREF NC FB2 OUT2 SKIP FREQUENCY FSEL BOOT2 HGATE2 PHASE2 CSENSE2 COMP2 LDO5 LGATE2 PGOOD2 SHDN EN2 20/49 VIN 5V REFERENCE VREF LINEAR GENERATOR REGULATOR LDO5 ENABLE SELECTOR LEVEL ...
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PM6680 7 Device description The PM6680 is a dual step-down controller dedicated to provide logic voltages for notebook computers based on a Constant On Time control architecture. This type of control offers a very fast load transient response ...
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Device description Figure 28. Constant ON time PWM control The duty cycle of the buck converter in steady state is: Equation 2 The PWM control works at a nearly fixed frequency f Equation 3 As mentioned the steady state switching ...
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PM6680 7.2 Constant on time architecture Figure 29 shows the simplified block diagram of a Constant On Time controller. A minimum off-time constrain (300 ns typ.) is introduced to allow inductor valley current sensing on synchronous switch. A minimum on-time ...
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Device description 7.3 Output ripple compensation and loop stability In a classic Constant On Time control, the system regulates the valley value of the output voltage and not the average value, as shown in voltage ripple is source of a ...
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PM6680 7.4 Pulse skip mode If the SKIP pin is tied to ground, the device works in skip mode. At light loads a zero-crossing comparator truncates the low-side switch on-time when the inductor current becomes negative. In this condition the ...
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Device description Figure 32. No audible skip mode The low side switch is turned on until the output voltage crosses about Vreg+1 %. Then the high side MOSFET is turned on for a fixed on time period. Afterwards the low ...
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PM6680 An internal 100 µA current source is connected to CSENSE pin and determines a voltage drop on R CSENSE drop, the controller doesn't initiate a new cycle. A new cycle starts only when the sensed current goes below the ...
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Device description Where RSNS is the sensing element (R PM6680 provides also a fixed negative peak current limit to prevent an excessive reverse inductor current when the switching section sinks current from the load in PWM mode. This negative current ...
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PM6680 When a switching section is turned off (EN1/EN2 pins low), the controller enters in soft end mode.The output capacitor is discharged through an internal 18 Ω P-MOSFET switch; when the output voltage reaches 0.3 V, the low-side MOSFET turns ...
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Device description 7.10 Internal linear regulator The PM6680 has an internal linear regulator providing 5 V (LDO5) at ±2 % accuracy. High side drivers, low side drivers and most of internal circuitry are supplied by LDO5 output through VCC pin ...
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PM6680 7.12 Monitoring and protections 7.12.1 Power good signals The PM6680 provides three independent power good signals: one for each switching section (PGOOD1/PGOOD2). PGOOD1/PGOOD2 signals are low if the output voltage is out of ± the designed set ...
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Device description 7.13 Design guidelines The design of a switching section starts from two parameters: ● Input voltage range: in notebook applications it varies from the minimum battery voltage, V INmin ● Maximum load current the maximum required ...
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PM6680 Equation 14 If hard saturation inductors are used, the inductor saturation current should be much greater than the maximum inductor peak current I Equation 15 Using soft saturation inductors it's possible to choose inductors with saturation current limit nearly ...
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Device description Table 11. Output capacitor manufacturer Manufacturer Series SANYO POSCAP TPB,TPD, TPE PANASONIC SPCAP UD, UE 7.13.4 Input capacitors selection In a buck topology converter the current that flows into the input capacitor is a pulsed current with zero ...
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PM6680 7.13.5 Power MOSFETs Logic-level MOSFETs are recommended, since low side and high side gate drivers are powered by LDO5. Their breakdown voltage VBR In notebook applications, power management efficiency is a high level requirement. The power dissipation on the ...
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Device description Equation 22 Choose a synchronous rectifier with low R variation of the phase node voltage can bring up even the low side gate through its gate- drain capacitance C that minimizes the ratio C Below there is a ...
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PM6680 7.13.6 Closing the integrator loop The design of external feedback network depends on the output voltage ripple. If the ripple is higher than approximately 30 mV, the feedback network ( keep the loop stable. Figure 36. Circuitry for output ...
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Device description In order to reduce ground noise due to load transient on the other section recommended to add a resistor R low pass filter (see times) than the switching frequency of the section: Equation 26 Due to ...
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PM6680 The T node voltage is the sum of the output voltage and the triangular waveform generated by the virtual ESR network. In fact the virtual ESR network behaves like a further equivalent ESR R . ESR A good trade-off ...
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Device description R must be chosen in order to have enough ripple voltage on integrator input: Equation 34 R1 can be selected as follows: Equation 35 Example: OUT1 = 1 design R ESR ...
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PM6680 Figure 39. Inductor current waveforms Typical components values are: R=47 Ω and uF. ● VREF capacitor 100 nF ceramic capacitor on VREF pin must be added to ensure noise rejection. ● LDO5 ...
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Device description 7.13.8 Design example The following design example considers an input voltage from The two switching outputs are OUT1=1.5 V and OUT2=1.05 V and must deliver a maximum current The selected ...
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PM6680 Equation 39 (Let's assume the maximum temperature Tmax = 75 °C in RDSon calculation) OUT2: Equation 40 Equation 41 (Let's assume Tmax = 75 ° Input capacitor Maximum input capacitor RMS current is about 2.8 A. ...
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Device description possible. Place the synchronous diode D near the LS MOSFET. Connect the LS MOSFET drain to the switching node with a short trace. ● Place input capacitors near HS MOSFET drain recommended to use the same ...
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PM6680 coupling place these traces as far as possible from the gate drivers and phase (switching) paths. ● Place the current sense traces on the bottom side. If low side MOSFET R is enabled, use a dedicated connection between the ...
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Package mechanical data 8 Package mechanical data In order to meet environmental requirements, ST offers these devices in ECOPACK packages. These packages have a Lead-free second level interconnect. The category of second Level Interconnect is marked on the package and ...
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PM6680 Figure 42. Package dimensions Package mechanical data 47/49 ...
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Revision history 9 Revision history Table 19. Document revision history Date 17-Mar-2006 10-May-2006 29-Jun-2006 28-Jul-2006 25-Oct-2006 28-Aug-2007 21-Jan-2008 48/49 Revision 1 Initial release 2 Few updates 3 Mechanical data updated 4 Application schematic updated Changes electrical characteristics, added COMP value ...
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... PM6680 Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. ...