IC PWM CTLR 1PH PWRGOOD 10DFN

L6728TR

Manufacturer Part NumberL6728TR
DescriptionIC PWM CTLR 1PH PWRGOOD 10DFN
ManufacturerSTMicroelectronics
L6728TR datasheet
 


Specifications of L6728TR

Pwm TypeVoltage ModeNumber Of Outputs1
Frequency - Max330kHzDuty Cycle80%
Voltage - Supply4.5 V ~ 12 VBuckYes
BoostNoFlybackNo
InvertingNoDoublerNo
DividerNoCukNo
IsolatedNoOperating Temperature-40°C ~ 125°C
Package / Case10-DFNFrequency-max330kHz
Output Voltage0.8 VOutput Current30 A
Input Voltage1.5 V to 13.2 VMounting StyleSMD/SMT
Maximum Operating Temperature+ 125 CMinimum Operating Temperature- 40 C
For Use With497-8228 - BOARD EVALUATION W/L6728497-6418 - BOARD EVAL BASED ON L6728Lead Free Status / RoHS StatusLead free / RoHS Compliant
Other names497-6274-2  
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Features
Flexible power supply from 5 V to 12 V
Power conversion input as low as 1.5 V
0.8 V internal reference
0.8 % output voltage accuracy
High-current integrated drivers
Power Good output
Sensorless and programmable OCP across
low-side R
DS(on)
OV / UV protections
VSEN disconnection protection
Oscillator internally fixed at 300 kHz
LSless to manage pre-bias start-up
Adjustable output voltage
Disable function
Internal soft-start
DFN10 package
Applications
Memory and termination supply
Subsystem power supply (MCH, IOCH, PCI...)
CPU and DSP power supply
Distributed power supply
General DC-DC converters
Table 1.
Device summary
Order codes
L6728
L6728TR
November 2008
Single phase PWM controller with Power Good
Description
L6728 is a single-phase step-down controller with
integrated high-current drivers that provides
complete control logic and protection to realize in
a simple way general DC-DC converters by using
a compact DFN10 package.
Device flexibility allows managing conversions
with power input V
supply voltage ranging from 5 V to 12 V.
L6728 provides simple control loop with voltage
mode EA. The integrated 0.8 V reference allows
regulating output voltages with ±0.8 % accuracy
over line and temperature variations. Oscillator is
internally fixed to 300 kHz.
L6728 provides programmable dual level over
current protection as well as over and under
voltage protection. Current information is
monitored across the low-side MOSFET R
saving the use of expensive and space-
consuming sense resistors.
PGOOD output easily provides real-time
information on output voltage status, through
VSEN dedicated output monitor.
Package
DFN10
Rev 4
L6728
DFN10
as low as 1.5 V and device
IN
DS(on)
Packaging
Tube
Tape and reel
1/31
www.st.com
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L6728TR Summary of contents

  • Page 1

    ... Distributed power supply ■ General DC-DC converters Table 1. Device summary Order codes L6728 L6728TR November 2008 Single phase PWM controller with Power Good Description L6728 is a single-phase step-down controller with integrated high-current drivers that provides complete control logic and protection to realize in a simple way general DC-DC converters by using a compact DFN10 package ...

  • Page 2

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

  • Page 3

    L6728 demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

  • 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 PGOOD L6728 Reference ...

  • Page 5

    L6728 2 Pin description and connection diagrams Figure 3. Pin connection (top view) 2.1 Pin descriptions Table 2. Pins description Pin # Name 1 BOOT 2 PHASE 3 UGATE 4 LGATE / OC 5 GND 6 VCC 7 COMP / ...

  • Page 6

    Thermal data Table 2. Pins description (continued) Pin # Name 9 VSEN 10 PGOOD 3 Thermal data Table 3. Thermal data Symbol Thermal resistance junction to ambient R th(JA) (Device soldered on 2s2p board) R ...

  • Page 7

    L6728 4 Electrical specifications 4.1 Absolute maximum ratings Table 4. Absolute maximum ratings Symbol VCC to GND to PHASE GND BOOT, UGATE to GND; t < 200 ns to GND V PHASE to GND; t < 200 ...

  • Page 8

    Electrical specifications Table 5. Electrical characteristics (continued Symbol Parameter Gate drivers I HS source current UGATE R HS sink resistance UGATE I LS source current LGATE R LS sink resistance LGATE ...

  • Page 9

    L6728 5 Device description L6728 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 in ...

  • Page 10

    Driver section 6 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 the high-side MOSFET uses BOOT pin for supply and PHASE pin for return. ...

  • Page 11

    L6728 7 Soft-start L6728 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 gradually increases the internal reference from 0 4.5 ...

  • Page 12

    Over current protection 8 Over current protection The over current function protects the converter from a shorted output or overload, by sensing the output current information across the low side MOSFET drain-source on- resistance, R DS(on) avoiding the use of ...

  • Page 13

    L6728 8.1 Over current threshold setting L6728 allows to easily program a 1 550 mV, simply by adding a resistor (R will be automatically set accordingly. During a short period of time (about 5 ms) following VCC rising over UVLO ...

  • Page 14

    Output voltage setting and protections 9 Output voltage setting and protections L6728 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 guarantee the ...

  • Page 15

    L6728 10 Application details 10.1 Compensation network The control loop showed in regulated to the internal reference (when present, offset resistor between FB node and GND can be neglected in control loop calculation). Error Amplifier output is compared to oscillator ...

  • Page 16

    Application details Figure 6. Example of type III compensation open loop EA gain closed loop gain compensation open loop converter gain ● Open loop converter singularities --------------------------------- - LC 2π ESR ● ...

  • Page 17

    L6728 b) Place ----------------------------- π Place ---------------------------------------------------------- P 2π Place -------------------------- - S F ----------------- - 1 ⋅ ------------------------------ ...

  • Page 18

    Application details Figure 7. Power connections (heavy lines) L6728 Gate traces and phase trace must be sized according to the driver RMS current delivered to the power MOSFET. The device robustness allows managing applications with the power section far from ...

  • Page 19

    L6728 11 Application information 11.1 Inductor design The inductance value is defined by a compromise between the dynamic response time, the efficiency, the cost and the size. The inductor has to be calculated to maintain the ripple current (ΔI ) ...

  • Page 20

    Application information 11.2 Output capacitor(s) The output capacitors are basic components to define the ripple voltage across the output and for the fast transient response of the power supply. They depend on the output voltage ripple requirements, as well as ...

  • Page 21

    L6728 demonstration board L6728 demonstration board realizes in a four-layer PCB a step-down DC/DC converter and shows the operation of the device in a general purpose application. The input voltage can range from ...

  • Page 22

    A demonstration board Figure 13 demonstration board schematic 22/31 L6728 ...

  • Page 23

    L6728 Table demonstration board - bill of material Qty Capacitors 2 C1 C10 3 C11 to C13 2 C14, C38 2 C15, C19 2 C18, C20 1 C23 1 C24 1 C35 Resistors 4 R1, ...

  • Page 24

    A demonstration board 12.1 Board description 12.1.1 Power input (Vin) This is the input voltage for the power conversion. The High-Side drain is connected to this input. This voltage can range from 1 bus. If ...

  • Page 25

    L6728 demonstration board L6728 demonstration board realizes in a two-layer PCB a step-down DC/DC converter and shows the operation of the device in a general-purpose low-current application. The input voltage can range from ...

  • Page 26

    A demonstration board Figure 17 demonstration board schematic 26/31 OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT COMP GND L6728 ...

  • Page 27

    L6728 Table demonstration board - bill of material Qty Capacitors 2 C12, C51 1 C10 2 C14, C38 1 C39 1 C30 2 C23, C36 1 C24 1 C35 Resistors 3 R1, R2, R17 3 R3, R5, ...

  • Page 28

    A demonstration board If the voltage is between 4.5 V and can supply also the device (through the Vcc pin) and in this case the R16 (0Ω) resistor must be present. 13.1.2 Output (Vout) The output ...

  • Page 29

    L6728 14 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 on the ...

  • Page 30

    Revision history 15 Revision history Table 9. Document revision history Date 29-Jun-2007 17-Sep-2007 05-Jun-2008 18-Nov-2008 30/31 Revision 1 Initial release 2 Updated T value in Table 3: Thermal data on page 6 J Added Figure 11 on page 21 3 ...

  • Page 31

    ... L6728 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. ...