IC CTRLR PWM SGL PHASE 8-SOIC

L6726ATR

Manufacturer Part NumberL6726ATR
DescriptionIC CTRLR PWM SGL PHASE 8-SOIC
ManufacturerSTMicroelectronics
TypeStep-Down (Buck)
L6726ATR datasheet
 


Specifications of L6726ATR

Internal Switch(s)NoSynchronous RectifierNo
Number Of Outputs1Voltage - OutputAdj to 0.8V
Frequency - Switching270kHzVoltage - Input1.5 ~ 12 V
Operating Temperature-20°C ~ 85°CMounting TypeSurface Mount
Package / Case8-SOIC (3.9mm Width)Output Current1.5 A
Input Voltage4.1 V to 13.2 VOperating Temperature Range- 40 C to + 150 C
Mounting StyleSMD/SMTFor Use With497-9046 - BOARD EVAL BASED ON L6726A497-6364 - BOARD DEMO FOR TS4995EIJT497-6259 - BOARD EVAL 1PH STPDN CONV L6726A
Lead Free Status / RoHS StatusLead free / RoHS CompliantCurrent - Output-
Power - Output-Other names497-5906-2
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Feature
Flexible power supply from 5 V to 12 V
Power conversion input as low as 1.5 V
1% output voltage accuracy
High-current integrated drivers
Adjustable output voltage
0.8 V internal reference
Sensorless and programmable OCP across
Low-side R
dsON
Oscillator internally fixed at 270 kHz
Programmable soft-start
Ls-less start up
Disable function
FB disconnection protection
SO-8 package
Applications
Subsystem power supply (MCH, IOCH, PCI...)
Memory and termination supply
CPU and DSP power supply
Distributed power supply
General DC / DC converters
Table 1.
Device summary
Order codes
L6726A
L6726ATR
March 2010
Single phase PWM controller
Description
L6726A is a single-phase step-down controller
with integrated high-current drivers that provides
complete control logic, protections and reference
voltage to realize in an easy and simple way
general DC-DC converters by using a compact
SO-8 package.
Device flexibility allows managing conversions
with power input V
supply voltage ranging from 5 V to 12 V.
L6726A provides simple control loop with trans-
conductance error amplifier. The integrated 0.8 V
reference allows regulating output voltage with
±1% accuracy over line and temperature
variations. Oscillator is internally fixed to 270 kHz.
L6726A provides programmable over current
protection. Current information is monitored
across the low-side MOSFET R
use of expensive and space-consuming sense
resistors.
FB disconnection protection prevents excessive
and dangerous output voltages in case of floating
FB pin.
Package
SO-8
SO-8
Doc ID 12754 Rev 4
L6726A
SO-8
as low as 1.5 V and device
IN
saving the
dsON
Packaging
Tube
Tape and reel
1/35
www.st.com
35

L6726ATR Summary of contents

  • Page 1

    ... Distributed power supply ■ General converters Table 1. Device summary Order codes L6726A L6726ATR March 2010 Single phase PWM controller Description L6726A is a single-phase step-down controller with integrated high-current drivers that provides complete control logic, protections and reference voltage to realize in an easy and simple way general DC-DC converters by using a compact SO-8 package ...

  • Page 2

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

  • Page 3

    L6726A 9 Application Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

  • Page 4

    Typical application circuit and block diagram 1 Typical application circuit and block diagram 1.1 Application circuit Figure 1. Typical application circuit 12V CC C DEC L6726A Reference Schematic (1) Up ...

  • Page 5

    L6726A 2 Pins description and connection diagrams Figure 3. Pins connection (top view) 2.1 Pin descriptions Table 2. Pins descriptions Pin n Name 1 BOOT 2 UGATE 3 GND 4 LGATE / OC 5 VCC COMP / ...

  • Page 6

    Pins description and connection diagrams 2.2 Thermal data Table 3. Thermal data Symbol R Thermal resistance junction to ambient thJA T Maximum junction temperature MAX T Storage temperature range STG T Junction temperature range J 1. Measured with the component ...

  • Page 7

    L6726A 3 Electrical specifications 3.1 Absolute maximum ratings Table 4. Absolute maximum ratings Symbol V to GND PHASE BOOT to GND V to PHASE UGATE to PHASE; t < 50ns to GND V to GND PHASE V ...

  • Page 8

    Electrical specifications Table 5. Electrical characteristics (continued) Symbol Parameter Reference Output voltage accuracy Transconductance error amplifier gm Transconductance I Input bias current FB (1) A Open loop gain 0 (1) F Unity gain 0 I COMP Current capability Soft-Start and ...

  • Page 9

    L6726A 4 Device description L6726A is a single-phase PWM controller with embedded high-current drivers that provides complete control logic and protections to realize in an easy and simple way a general DC- DC step-down converter. Designed to drive N-channel MOSFETs ...

  • Page 10

    Driver section 5 Driver section The integrated high-current drivers allow using different types of power MOSFET (also multiple MOSFETs to reduce the equivalent R The driver for high-side MOSFET uses BOOT pin for supply and PHASE pin for return. The ...

  • Page 11

    L6726A 5.1 Power dissipation L6726A embeds high current MOSFET drivers for both high side and low side MOSFETs then important to consider the power that the device is going to dissipate in driving them in order to avoid ...

  • Page 12

    Soft start and disable 6 Soft start and disable L6726A implements a soft start to smoothly charge the output filter avoiding high in-rush currents to be required from the input power supply. The device sources a 10 µA soft start ...

  • Page 13

    L6726A 7 Protections 7.1 Overcurrent protection The overcurrent feature protects the converter from a shorted output or overload, by sensing the output current information across the low side MOSFET drain-source on-resistance This method reduces cost and enhances converter ...

  • Page 14

    Protections Figure 6. OC threshold setting procedure timings (top) and waveforms (bottom) UVLO Th VCC PWM ramp bottom edge Enable Th COMP 700mV LGATE 7.3 Undervoltage lock out In order to avoid anomalous behaviors of the device when the supply ...

  • Page 15

    L6726A 8 Application details 8.1 Output voltage selection L6726A is capable to precisely regulate an output voltage as low as 0 fact, the device comes with a fixed 0.8 V internal reference that guarantees the output regulated voltage ...

  • Page 16

    Application details depending on the output capacitor ESR. The DC gain of the modulator is simply the input divided by the peak-to-peak oscillator voltage ΔV voltage scaled and transferred to FB node by the output resistor ...

  • Page 17

    L6726A Type II compensation relies on the zero introduced by the output capacitors bank to achieve stability. Thus, a needed condition to successfully apply type II compensation is (usually true when output capacitor is based on electrolytic, aluminium electrolytic or ...

  • Page 18

    Application details 8.3 Soft-start time calculation To calculate SS time ( The previous equation refers only setting phase or COMP set free to the beginning of V approximately estimated as follow: t delay Once calculated ...

  • Page 19

    L6726A Connect output bulk capacitors (C inductance and resistance associated to the copper trace, also adding extra decoupling capacitors along the way to the load when this results in being far from the bulk capacitors bank. Gate traces and phase ...

  • Page 20

    Application details 8.5 Embedding L6726A-based VRs… When embedding the VR into the application, additional care must be taken since the whole switching DC/DC regulator and the most common system in which it has to work is a ...

  • Page 21

    L6726A 9 Application Information 9.1 Output inductor Inductor value is defined by a compromise between dynamic response, ripple, efficiency, cost and size. Usually, inductance is calculated to maintain inductor ripple current (ΔI between 20% and 30% of maximum output current. ...

  • Page 22

    Application Information 9.2 Output capacitors Output capacitors choice depends on the application constraints in point of output voltage ripple and output voltage deviation during a load transient. During steady-state conditions, the output voltage ripple is influenced by ESR and capacitance ...

  • Page 23

    L6726A demonstration board L6726A demonstration board realizes on a four-layer PCB a step-down DC/DC converter and shows the operation of the device in a general purpose application. Input voltage can range from ...

  • Page 24

    A demonstration board Figure 15 demonstration board inner layers 24/35 Doc ID 12754 Rev 4 L6726A ...

  • Page 25

    L6726A Figure 16 demonstration board schematic PHASE PHASE HSD GND GND PHASE HSD HSD 2 ...

  • Page 26

    A demonstration board Table demonstration board - bill of material Qty Capacitors 2 C1 C10 3 C11 to C13 2 C14, C38 2 C18, C25 1 C23 1 C24 1 C35 Resistors 3 R1, ...

  • Page 27

    L6726A 10.1 Board description 10.1.1 Power input (VIN) This is the input voltage for the power conversion. The high-side MOSFET drain is connected to this input. Supply must be compliant with VIN recommended operating conditions and capacitors rating. If VIN ...

  • Page 28

    A demonstration board demonstration board L6726A demonstration board realizes on a two-layer PCB a step-down DC/DC converter and shows the operation of the device in a general-purpose low-current application. Input voltage can range from 5 V ...

  • Page 29

    L6726A Figure 20 demonstration board schematic L6726A L6726A GND Doc ID 12754 Rev demonstration board OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT COMP ...

  • Page 30

    A demonstration board Table demonstration board - bill of material Qty Capacitors 2 C12, C51 1 C10 2 C14, C38 1 C39 1 C30 1 C23 1 C24 1 C35 Resistors R3, R5, ...

  • Page 31

    L6726A 11.1.2 Power output (VOUT) This is the output voltage of the power conversion. The output voltage is programmed to 1. can be changed by replacing R13 (adjusting of compensation network may be needed). Adding R18 allows to ...

  • Page 32

    Package mechanical data 12 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 ...

  • Page 33

    L6726A Table 8. SO-8 mechanical data Dim ( ddd 1. D and F does not include mold flash or protrusions. Mold flash or potrusions shall not exceed 0.15mm ...

  • Page 34

    Revision history 13 Revision history Table 9. Document revision history Date 16-Oct-2006 26-Oct-2006 30-Jul-2007 23-Mar-2010 34/35 Revision 1 Initial release. 2 Mechanical data dimensions updated 3 Updated Figure 1 on page Added: 4 Section 9 on page 21, Updated: Table ...

  • Page 35

    ... L6726A 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. ...