IC PWM CTLR 1PH POWERGOOD 10DFN

L6728DTR

Manufacturer Part NumberL6728DTR
DescriptionIC PWM CTLR 1PH POWERGOOD 10DFN
ManufacturerSTMicroelectronics
L6728DTR datasheet
 


Specifications of L6728DTR

Pwm TypeVoltage ModeNumber Of Outputs1
Frequency - Max330kHzDuty Cycle80%
Voltage - Supply5 V ~ 12 VBuckYes
BoostNoFlybackNo
InvertingNoDoublerNo
DividerNoCukNo
IsolatedNoOperating Temperature-40°C ~ 125°C
Package / Case10-DFNFrequency-max330kHz
Duty Cycle (max)80 %Mounting StyleSMD/SMT
Switching Frequency300 KHzOperating Supply Voltage5 V to 12 V
Supply Current6 mALead Free Status / RoHS StatusLead free / RoHS Compliant
Other names497-10432-2  
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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 protection
VSEN disconnection protection
Oscillator internally fixed at 300 kHz
LSLess to manage pre-bias startup
Adjustable output voltage
Disable function
Internal soft-start
DFN10 package
Applications
Memory and termination supply
Subsystem power supply (MCH, IOCH, PCI,
etc.)
CPU and DSP power supply
Distributed power supply
General DC-DC converters
Table 1.
Device summary
Order codes
L6728D
L6728DTR
February 2010
Single-phase PWM controller with Power Good
Description
L6728D is a single-phase step-down controller
with integrated high-current drivers that provides
complete control logic and protection to simplify
the design of general DC-DC converters by using
a compact DFN10 package.
Device flexibility allows the management of
conversions with power input (V
1.5 V, and device supply voltage ranging from 5 V
to 12 V.
The L6728D provides a simple control loop with
voltage mode EA. The integrated 0.8 V reference
allows output voltages regulation with ±0.8%
accuracy over line and temperature variations.
The oscillator is internally fixed to 300 kHz.
The L6728D provides programmable dual level
overcurrent protection, as well as overvoltage and
undervoltage protection. Current information is
monitored across the low-side MOSFET R
eliminating the need for expensive and space-
consuming sense resistors.
A PGOOD output easily provides real-time
information on output voltage status, through the
VSEN dedicated output monitor.
Package
DFN10
Doc ID 16498 Rev 1
L6728D
DFN10
) as low as
IN
,
DS(on)
Packaging
Tube
Tape and reel
1/33
www.st.com
33

L6728DTR Summary of contents

  • Page 1

    ... Distributed power supply ■ General DC-DC converters Table 1. Device summary Order codes L6728D L6728DTR February 2010 Single-phase PWM controller with Power Good Description L6728D is a single-phase step-down controller with integrated high-current drivers that provides complete control logic and protection to simplify the design of general DC-DC converters by using a compact DFN10 package ...

  • Page 2

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

  • Page 3

    L6728D 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 of the L6728D 12V CC C DEC PGOOD ...

  • Page 5

    L6728D 2 Pin description and connection diagram Figure 3. Pin connection (top view) 2.1 Pin descriptions Table 2. Pins description Pin n° Name HS driver supply. Connect through a capacitor (100 nF) to the floating node (LS-Drain) pin 1 BOOT ...

  • Page 6

    Thermal data 3 Thermal data Table 3. Thermal data Symbol Thermal resistance junction-to-ambient R th(JA) (device soldered on 2s2p board) R Thermal resistance junction-to-case th(JC) T Maximum junction temperature MAX T Storage temperature range STG ...

  • Page 7

    L6728D 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 Overcurrent protection I OCSET current source OCSET V OC ...

  • Page 9

    L6728D 5 Device description The L6728D is a single-phase PWM controller with embedded high-current drivers which provides complete control logic and protection features for easy implementation of a general DC-DC step-down converter. Designed to drive N-channel MOSFETs in a synchronous ...

  • Page 10

    Driver section 6 Driver section The integrated high-current drivers permit the use of different types of power MOSFETs (also multiple MOSFETs to reduce the equivalent R transition. The driver for the high-side MOSFET uses the BOOT pin for supply and ...

  • Page 11

    L6728D External gate resistors help the device to dissipate the switching power since the same power P is shared between the internal driver impedance and the external resistor, SW resulting in a general cooling of the device. Doc ID 16498 ...

  • Page 12

    Soft-start 7 Soft-start The L6728D implements a soft-start to smoothly charge the output filter, avoiding the high in-rush currents to be required from the input power supply. The device gradually increases the internal reference from 0.8 V ...

  • Page 13

    L6728D 8 Overcurrent protection The overcurrent 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 expensive and space-consuming sense ...

  • Page 14

    Overcurrent protection 8.1 Overcurrent threshold setting The L6728D allows easy programming 550 mV, simply by adding a resistor (R level threshold is automatically set accordingly. During a short period of time (about 5 ms) following ...

  • Page 15

    L6728D 9 Output voltage setting and protections The L6728D is capable of precisely regulating an output voltage as low as 0 fact, the device is equipped with a fixed 0.8 V internal reference that guarantees the output regulated ...

  • Page 16

    Application details 10 Application details 10.1 Compensation network The control loop shown in regulated to the internal reference (when present, the offset resistor between the FB node and GND can be neglected in control loop calculation). The error amplifier output ...

  • Page 17

    L6728D 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 ● Compensation ...

  • Page 18

    Application details b) Place ----------------------------- π Place ---------------------------------------------------------- P 2π Place -------------------------- - S F ----------------- - ------------------------------ - S π ...

  • Page 19

    L6728D Figure 7. Power connections (heavy lines) L6728A Gate traces and phase traces must be sized according to the driver RMS current delivered to the power MOSFET. The device robustness allows the management of applications with the power section far ...

  • Page 20

    Application information 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 21

    L6728D 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 any ...

  • Page 22

    A demonstration board demonstration board The L6728D demonstration board is constructed using a four-layer PCB, and is designed as a step-down DC-DC converter. The board demonstrates the operation of the device in a general-purpose application. The ...

  • Page 23

    L6728D Figure 13 demonstration board schematic Doc ID 16498 Rev demonstration board 23/33 ...

  • Page 24

    A demonstration board 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 ...

  • Page 25

    L6728D 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 the voltage is ...

  • Page 26

    A demonstration board demonstration board The L6728D demonstration board is constructed using a two-layer PCB, and is designed as a step-down DC-DC converter. The board demonstrates the operation of the device in a general-purpose, low-current application. ...

  • Page 27

    L6728D Figure 17 demonstration board schematic GND Doc ID 16498 Rev demonstration board OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT COMP 27/33 ...

  • Page 28

    A demonstration board 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 ...

  • Page 29

    L6728D 13.1 Board description 13.1.1 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 the voltage is ...

  • Page 30

    A demonstration board 13.1.5 Board characterization Figure 18 demonstration board efficiency 30/33 Doc ID 16498 Rev 1 L6728D ...

  • Page 31

    L6728D 14 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 at: www.st.com. ...

  • Page 32

    Revision history 15 Revision history Table 9. Document revision history Date 03-Feb-2010 32/33 Revision 1 Initial release. Doc ID 16498 Rev 1 L6728D Changes ...

  • Page 33

    ... L6728D 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. ...