L6728ATR

Manufacturer Part NumberL6728ATR
DescriptionIC CTLR PWM SGL HI FREQ 10VFQFPN
ManufacturerSTMicroelectronics
L6728ATR datasheet
 


Specifications of L6728ATR

Pwm TypeVoltage ModeNumber Of Outputs1
Frequency - Max660kHzDuty Cycle67%
Voltage - Supply5 V ~ 12 VBuckYes
BoostNoFlybackNo
InvertingNoDoublerNo
DividerNoCukNo
IsolatedNoOperating Temperature-40°C ~ 125°C
Package / Case10-DFNFrequency-max660kHz
TopologyBuckOutput Voltage0.8 V
Output Current1500 mASwitching Frequency660 KHz
Duty Cycle (max)67 %Maximum Operating Temperature+ 125 C
Minimum Operating Temperature- 40 CSynchronous PinNo
For Use With497-8228 - BOARD EVALUATION W/L6728497-6418 - BOARD EVAL BASED ON L6728Lead Free Status / RoHS StatusLead free / RoHS Compliant
Other names497-8324-2  
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High frequency single phase PWM controller with Power Good
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 600 kHz
LS-LESS to manage pre-bias start-up
Adjustable output voltage
Disable function
Internal soft-start
VFDFPN 10 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
L6728A
L6728ATR
October 2008
VFQFPN 10
Description
L6728A 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 VFDFPN 10 package.
Device flexibility allows managing conversions
with power input V
as low as 1.5 V and device
IN
supply voltage ranging from 5 V to 12 V.
L6728A 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 600 kHz.
L6728A 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
VFDFPN 10
VFDFPN 10
Rev 1
L6728A
DS(on)
Packing
Tube
Tape and reel
1/32
www.st.com
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L6728ATR Summary of contents

  • Page 1

    ... Distributed power supply ■ General converters Table 1. Device summary Order codes L6728A L6728ATR October 2008 VFQFPN 10 Description L6728A 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 VFDFPN 10 package ...

  • Page 2

    L6728A Contents 1 Typical application circuit and block diagram . . . . . . . . . . . . . . . . . . . . 4 1.1 Application circuit . . . . . . . ...

  • Page 3

    L6728A demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

  • Page 4

    L6728A 1 Typical application circuit and block diagram 1.1 Application circuit Figure 1. Typical application circuit 12V CC C DEC PGOOD L6728A Reference Schematic 1.2 Block diagram Figure ...

  • Page 5

    L6728A 2 Pins description and connection diagrams Figure 3. Pins connection (top view) 2.1 Pin descriptions Table 2. Pin description Pin # Name 1 BOOT 2 PHASE 3 UGATE 4 LGATE / OC 5 GND 6 VCC 7 COMP / ...

  • Page 6

    L6728A Table 2. Pin description (continued) Pin # Name 9 VSEN 10 PGOOD 2.2 Thermal data Table 3. Thermal data Symbol Thermal resistance junction to ambient R TH(JA) (Device soldered on 2s2p board) R Thermal ...

  • Page 7

    L6728A 3 Electrical specifications 3.1 Absolute maximum ratings Table 4. Absolute maximum ratings Symbol V to GND CC to PHASE GND BOOT, UGATE to GND; t < 200 ns to GND V PHASE to GND; t < ...

  • Page 8

    L6728A 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 Over-current ...

  • Page 9

    L6728A 4 Device description L6728A 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

    L6728A 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 the high-side MOSFET uses BOOT pin for supply and PHASE pin for return. The ...

  • Page 11

    L6728A 6 Soft-start L6728A 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

    L6728A 7 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 expensive and space-consuming sense ...

  • Page 13

    L6728A 8 Output voltage setting and protections L6728A 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 output regulated voltage to ...

  • Page 14

    L6728A 9 Application details 9.1 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 15

    L6728A 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 16

    L6728A b) Place ----------------------------- π Place ---------------------------------------------------------- P 2π Place -------------------------- - S F ----------------- - 1 ⋅ ------------------------------ ...

  • Page 17

    L6728A Figure 7. Power connections (heavy lines) L6728A 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 the ...

  • Page 18

    L6728A 10 Application information 10.1 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 19

    L6728A 10.2 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 20

    L6728A demonstration board L6728A 20 A demonstration board realizes two-layer PCB, a step-down DC/DC converter and shows the operation of the device in a general-purpose high-current application. Different output voltage rails have been considered: 8 ...

  • Page 21

    L6728A Figure 11 demonstration board schematic 20 A demonstration board 21/32 ...

  • Page 22

    L6728A Table 6. 20A demonstration board - bill of material (common components) Qty Capacitors 2 C1 C10 3 C11 to C13 2 C14, C38 C3 to C9, C15 to C20, C39 to 48 C59, C36, C37, C21 to ...

  • Page 23

    L6728A 11.1 Demonstration board description 11.1.1 Power input (V 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 ...

  • Page 24

    L6728A 11.2 Demonstration board characterization Figure 12 and Figure 17 accuracy and efficiency. Figure 12 demonstration board performances Load / Line Regulation 0,3% 0,2% 0,1% 0,0% -0,1% -0,2% -0, 100% 90% 80% 70% 60% ...

  • Page 25

    L6728A 12 5A demonstration board L6728A 5 A demonstration board realizes two-layer PCB, a step-down DC/DC converter and shows the operation of the device in a general-purpose high-current application. Different output voltage rails have been considered ...

  • Page 26

    L6728A Figure 15 demonstration board schematic 5A demonstration board 26/32 ...

  • Page 27

    L6728A Table demonstration board - bill of material Qty Capacitors 2 C12, C51 1 C10 2 C14, C38 2 C39, C40 2 C36 1 C24 1 C35 Resistors 3 R1, R2, R17 3 R3, R5, R16 1 ...

  • Page 28

    L6728A 12.1 Demonstration board description 12.1.1 Power input (V 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 ...

  • Page 29

    L6728A 12.2 Demonstration board characterization Figure 16 and Figure 17 terms of accuracy and efficiency. Figure 16 demonstration board performances Load / Line Regulation 0,3% 0,2% 0,1% 0,0% -0,1% -0,2% -0, 100% 90% 80% ...

  • Page 30

    L6728A 13 Mechanical data and package dimensions Figure 18. Mechanical data and package dimensions DIMENSIONS mm REF. MIN. TYP. MAX. MIN. A 0.80 0.90 A1 0.02 A2 0.70 A3 0.20 b 0.18 0.23 D 3.00 D2 2.21 2.26 E 3.00 ...

  • Page 31

    L6728A 14 Revision history Table 10. Document revision history Date 01-Oct-2008 Revision 1 Initial release Revision history Changes 31/32 ...

  • Page 32

    ... L6728A 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. ...