L6711TR STMicroelectronics, L6711TR Datasheet

IC CTRLR 3PHASE VID/DACS 48-TQFP

L6711TR

Manufacturer Part Number
L6711TR
Description
IC CTRLR 3PHASE VID/DACS 48-TQFP
Manufacturer
STMicroelectronics
Type
Step-Down (Buck)r
Datasheet

Specifications of L6711TR

Internal Switch(s)
No
Synchronous Rectifier
No
Number Of Outputs
1
Voltage - Output
0.8 ~ 1.55 V
Current - Output
2A
Frequency - Switching
150kHz
Voltage - Input
12V
Operating Temperature
0°C ~ 70°C
Mounting Type
Surface Mount
Package / Case
48-TQFP Exposed Pad, 48-eTQFP, 48-HTQFP, 48-VQFP
Power - Output
2.5W
Output Voltage
0.8 V to 1.581 V
Output Current
95 A
Input Voltage
13.8 V
Mounting Style
SMD/SMT
Maximum Operating Temperature
+ 125 C
Minimum Operating Temperature
0 C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
497-5363-2
L6711TR

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Quantity
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Manufacturer:
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Quantity:
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Features
Applications
Order codes
April 2006
2A integrated gate drivers
Fully differential current reading across
inductor or LS MOSFET
0.5% Output voltage accuracy
6 bit programmable output from 0.8185V to
1.5810V in 12.5mV steps
5 bit programmable output from 0.800V to
1.550V in 25mV steps
Dynamic VID management
Adjustable reference voltage offset
3% active current sharing accuracy
Digital 2048 step soft-start
Programmable over voltage protection
Integrated temperature sensor
Constant over current protection
Oscillator internally fixed at 150kHz (450kHz
ripple) externally adjustable
Output enable
Integrated remote sense buffer
TQFP48 7x7 Package with exposed pad
High current VRM/VRD for desktop / Server /
Workstation CPUs
High density DC/DC Converters
Part Number
L6711TR
3 Phase controller with dynamic VID and selectable DACs
L6711
Package
TQFP48
TQFP48
Rev 4
Description
The device implements a three phase step-down
controller with a 120° phase-shift between each
phase with integrated high current drivers in a
compact 7x7mm body package with exposed pad.
The device embeds selectable DAC: the output
voltage ranges from 0.8185V to 1.5810V with
12.5mV steps (VID_SEL = OPEN) or from 0.800V
to 1.550V with 25mV steps (VID_SEL = GND;
VID5 drives an optional +25mV offset) managing
dynamic VID with 0.5% accuracy over line and
temp variations. Additional programmable offset
can be added to the voltage reference with a
single external resistor.
The device assures a fast protection against load
over current and load over/under voltage. An
internal crowbar is provided turning on the low
side mosfet if an over-voltage is detected.
In case of over-current, the system works in
Constant Current mode until UVP.
Selectable current reading adds flexibility in
system design.
TQFP48 (Exposed Pad)
Tape & Reel
Packing
Tube
L6711
www.st.com
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Related parts for L6711TR

L6711TR Summary of contents

Page 1

... High current VRM/VRD for desktop / Server / Workstation CPUs High density DC/DC Converters Order codes Part Number L6711 L6711TR April 2006 TQFP48 (Exposed Pad) Description The device implements a three phase step-down controller with a 120° phase-shift between each phase with integrated high current drivers in a compact 7x7mm body package with exposed pad ...

Page 2

Contents Contents 1 Typical application circuit and block diagram . . . . . . . . . . . . . . . . . . . . 4 1.1 Application circuit . . . . . . . ...

Page 3

L6711 12 Enable and disable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

Page 4

Typical application circuit and block diagram 1 Typical application circuit and block diagram 1.1 Application circuit Figure 1. Typical application circuit for LS MOSFET current sense V IN GND IN VID5 VID4 VID3 VID2 VID1 VID0 VID_SEL OUTEN C F ...

Page 5

L6711 Figure 2. Typical application circuit for inductor DCR current sense V IN GND IN VID5 VID4 VID3 VID2 VID1 VID0 VID_SEL OUTEN L6711 REF. SCH. (INDUCTOR) Typical application circuit and block diagram L ...

Page 6

Typical application circuit and block diagram 1.2 Block diagram Figure 3. Block diagram OUTEN OUTEN OSC TC DIGITAL SOFT START VID0 VID1 VID2 VID3 VID4 VID5 VID_SEL 1.240V 6/50 HS1 HS1 HS2 LS2 LOGIC PWM LOGIC PWM ADAPTIVE ANTI ADAPTIVE ...

Page 7

L6711 2 Pins description and connection diagrams Figure 4. Pins connection (top view) N.C. VCCDR3 PGND2 LGATE2 VCCDR2 PHASE2 UGATE2 BOOT2 BOOT1 UGATE1 PHASE1 N.C. 2.1 Pin descriptions Table 1. Pins description N° Name Channel 1 LS driver supply: it ...

Page 8

Pins description and connection diagrams Table 1. Pins description N° Name This pin is connected to the error amplifier inverting input and is used to compensate the voltage control feedback loop Connecting a resistor between this pin and ...

Page 9

L6711 Table 1. Pins description N° Name Channel 2 Current Sense Positive Input pin. It must be connected through an Rg resistor to the LS mosfet source (or to the GND-side of the sense resistor placed in series to the ...

Page 10

Pins description and connection diagrams Table 1. Pins description N° Name Voltage IDentification pins. Internally pulled-up to 3V, connect to SGND to program a logic ‘0’ while leave floating (as well VID5, as pull-up with a resistor up to 3.3V) ...

Page 11

L6711 Table 1. Pins description N° Name Channel 1 HS driver supply. This pin supplies the relative high side driver. 45 BOOT1 Connect through a capacitor (100nF Typ.) to the PHASE1 pin and through a diode to VCC (cathode vs. ...

Page 12

Maximum ratings 3 Maximum ratings 3.1 Absolute maximum ratings Table 2. Absolute maximum ratings Symbol V , VCCDRx To PGNDx BOOTx Boot Voltage V PHASEx V - UGATEx V PHASEx LGATEx, PHASEx to PGNDx VID0 to VID5 ...

Page 13

L6711 4 Electrical specifications Table 4. Electrical characteristcs (V CC Symbol V supply current CC I VCC supply current CC VCCDRx supply I CCDRx current I BOOTx supply current BOOTx Power-ON Turn-On VCC threshold Turn-Off VCC threshold Turn-On VCCDRx Threshold ...

Page 14

Electrical specifications Table 4. Electrical characteristcs (continued Symbol Reference and DAC Output Voltage Accuracy VID, VID_SEL I , VID I pull-up Current VID_SEL VID, VID_SEL pull-up Voltage VID, VID_SEL VID IL Threshold VID IH Error amplifier A DC ...

Page 15

L6711 Table 4. Electrical characteristcs (continued Symbol Thermal sensor TC Voltage 27ºC amb Gate drivers High Side t RISE HGATE Rise Time High Side I HGATEx Source Current High Side R HGATEx Sink ...

Page 16

VID Tables 5 VID Tables Table 5. Voltage IDentification (VID) Codes. VID5 VID4 VID3 VID2 VID1 VID0 ...

Page 17

L6711 Table 6. Voltage IDentification (VID) Codes. HAMMER DAC VID5 VID4 VID3 VID2 VID1 VID0 ...

Page 18

Device description 6 Device description The device is a three phase PWM controller with embedded high current drivers that provides complete control logic and protections for a high performance step-down DC-DC voltage regulator optimized for advanced microprocessor power supply. Multi ...

Page 19

L6711 7 Current reading and current sharing control loop The device embeds a flexible, fully-differential current sense circuitry that is able to read across both low side or inductor parasitic resistance or across a sense resistor placed in series to ...

Page 20

Current reading and current sharing control loop 50 A offset allows negative current reading, enabling the device to check for dangerous returning current between the phases assuring the complete current equalization. From the current information of each phase, information about ...

Page 21

L6711 current information of each phase, information about the total current delivered ( INFO1 INFO2 INFO3 I )/3) is taken. I INFO3 in order to equalize the current carried by the three phases. Since Rg is ...

Page 22

DAC Selection 8 DAC Selection The device embeds a selectable DAC that allows the output voltage to have a tolerance of ±0.5% (0.6% for Hammer DAC) recovering from offsets and manufacturing variations. The VID_SEL pin selects the DAC table used ...

Page 23

L6711 9 Remote voltage sense The device embeds a Remote Sense Buffer to sense remotely the regulated voltage without any additional external components. In this way, the output voltage programmed is regulated between the remote buffer inputs compensating motherboard or ...

Page 24

Voltage positioning 10 Voltage positioning Output voltage positioning is performed by selecting the reference DAC and by programming the different contributors to the I sourced from the FB pin, causes the output voltage to vary according to the external R ...

Page 25

L6711 Since I depends on the current information about the three phases, the output DROOP characteristic vs. load current is given by: VID R – OOP Where R is the chosen sensing element resistance (Inductor DCR or ...

Page 26

Voltage positioning Offset resistor can be designed by considering the following relationship (R Droop effect): 1.240V R = ------------------ - R OFFSET V OS Offset automatically given by the DAC selection or by VID5 when VID_SEL=SGND differs from the offset ...

Page 27

L6711 The ITS circuit subtracts from the I temperature as follow (see considered): V T,I VID R = OUT OUT where ---------- - where A and B are positive constants depending on the value ...

Page 28

Dynamic VID transitions 11 Dynamic VID transitions The device is able to manage Dynamic VID Code changes that allow Output Voltage modification during normal device operation. OVP and UVP signals are masked during every VID transition and they are re-activated ...

Page 29

L6711 11.1 VID_SEL = OPEN. Selecting the VRD10.x DAC, the device checks for VID code modifications on the rising edge of a clock that is three times the switching frequency of each phase and waits for a confirmation on the ...

Page 30

Dynamic VID transitions 11.2 VID_SEL = GND. Selecting the HAMMER DAC, the device checks for VID code modifications on the rising edge of a clock that is the same frequency of each phase and waits for a confirmation on the ...

Page 31

L6711 12 Enable and disable The device has three different supplies: VCC pin to supply the internal control logic, VCCDRx to supply the low side drivers and BOOTx to supply the high side drivers. If the voltage at pins VCC ...

Page 32

Soft start 13 Soft start During soft start, a ramp is generated increasing the loop reference from 0V to the final value programmed by VID in 2048 clock periods as shown in Figure 15. Once the soft start begins, the ...

Page 33

L6711 14 Output voltage monitor and protections The device monitors through pin VSEN the regulated voltage in order to manage the OVP / UVP conditions. 14.1 UVP protection If the output voltage monitored by VSEN drops below the 60% of ...

Page 34

Output voltage monitor and protections Figure 16. Output voltage protections and typical principle connections to assure complete protection Vcc TurnON PreOVP TurnON 14.4 Over current Depending on the current reading method selected, the device limits the peak or ...

Page 35

L6711 14.5 Low side sense overcurrent (CS_SEL=OPEN) The device detects an Over Current condition for each phase when the current information I overcomes the fixed threshold of I INFOx keeps the relative LS mosfet on, skipping clock cycles, until the ...

Page 36

Output voltage monitor and protections 14.5.2 Constant current operation This happens when the on-time limitation is reached after the valley current in each phase reaches I (I OCPx INFOx The device enters in Quasi-Constant-Current operation: the low-side mosfets stays ON ...

Page 37

L6711 Figure 18. Constant current operation Maximum current for each phase 14.6 Inductor sense over current (CS_SEL = SGND) The device detects an over current when the I Since the device always senses ...

Page 38

Oscillator 15 Oscillator The internal oscillator generates the triangular waveform for the PWM charging and discharging with a constant current an internal capacitor. The switching frequency for each channel internally fixed at 150kHz so that the resulting ...

Page 39

L6711 16 Driver section The integrated high-current drivers allow using different types of power MOS (also multiple MOS to reduce the equivalent R The drivers for the high-side mosfets use BOOTx pins for supply and PHASEx pins for return. The ...

Page 40

Driver section Moreover, since the device has an exposed pad to better dissipate the power, also the thermal resistance between junction and ambient is important. Figure 16 shows the Switching Power for different kind of mosfets driven. Figure 20. Controller ...

Page 41

L6711 17 System control loop compensation The control loop is composed by the Current Sharing control loop and the Average Current Mode control loop. Each loop gives, with a proper gain, the correction to the PWM in order to minimize ...

Page 42

System control loop compensation V 4 PWM = -- - --------------- 5 V amplitude and has a typical value of 3V Removing the dependence from the Error Amplifier gain, so assuming this gain high enough, the control loop gain results: ...

Page 43

L6711 Figure 22. Equivalent Control Loop Gain Block Diagram (left) and Bode Diagram (right ...

Page 44

Layout guidelines 18 Layout guidelines Since the device manages control functions and high-current drivers, layout is one of the most important things to consider when designing such high current applications. A good layout solution can generate a benefit in lowering ...

Page 45

L6711 18.2 Power connections related. Figure 24 shows some small signal components placement. Gate and phase traces must be sized according to the driver RMS current delivered to the power mosfet. The device robustness allows managing applications with the power ...

Page 46

Layout guidelines 18.3 Current sense connections. Remote Buffer: The input connections for this component must be routed as parallel nets from the FBG/FBR pins to the load in order to compensate losses along the output power traces and also to ...

Page 47

L6711 19 Embedding L6711-based VRDs... When embedding the VRD into the application, additional care must be taken since the whole VRD is a switching DC/DC regulator and the most common system in which it has to work is a digital ...

Page 48

TQFP48 Mechanical data & package dimensions 20 TQFP48 Mechanical data & package dimensions Figure 25. TQFP48 Mechanical data & package dimensions mm DIM. MIN. TYP 0.05 A2 0.95 1.00 b 0.17 0.22 c 0.09 D 8.80 9.00 D1 ...

Page 49

L6711 21 Revision history Table 8. Revision History Date 01-Jun-2004 23-Nov-2004 26-Oct-2005 18-Apr-2006 Revision 1 First Issue 2 Modificated the Paragraph 18.2 on the page 32/38. 3 Added new paragraph 9.1.2 Warning 2. 4 Updated graphic, Modified Table1 Revision history ...

Page 50

... 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. ...

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