Regulators. L6728H Datasheet

L6728H Datasheet PDF

Part L6728H
Description Single-phase Switching DC-DC Controllers & Smart Regulators
Feature www.DataSheet4U.com L6728H Single phase PWM controller with Power Good Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■.
Manufacture ST Microelectronics
Datasheet
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L6728H
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L6728H
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 RDS(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
DFN10
Description
L6728H 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 VIN as low as 1.5 V and device
supply voltage ranging from 5 V to 12 V.
L6728H 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.
L6728H provides programmable dual level over
current protection as well as over and under
voltage protection. Current information is
monitored across the low-side MOSFET RDS(on)
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.
Table 1.
Device summary
Order codes
L6728H
L6728HTR
Package
DFN10
Packaging
Tube
Tape and reel
May 2009
Doc ID 15725 Rev 1
1/32
www.st.com
32



L6728H
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Contents
L6728H
1 Typical application circuit and block diagram . . . . . . . . . . . . . . . . . . . . 4
1.1 Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Pin description and connection diagrams . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Pin descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4 Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5 Device description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6 Driver section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1 Power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7 Soft-start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1 Low-side-less startup (LSLess) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
8 Over current protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.1 Over current threshold setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
9 Output voltage setting and protections . . . . . . . . . . . . . . . . . . . . . . . . 14
10 Application details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
10.1 Compensation network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
10.2 Layout guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
11 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
11.1 Inductor design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
11.2 Output capacitor(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
11.3 Input capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2/32 Doc ID 15725 Rev 1




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