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L6722TR

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P34
May 2006 Rev 1 1/34
34
L6722
3 Phase controller for DC/DC converters
Features
■ 2A integrated gate drivers
■ 0.8V reference
■ 1% output voltage accuracy
■ Adjustable reference offset
■ Precise current sharing and OCP across LS
MOSFETS
■ Constant over current protection
■ Feedback disconnection
■ LSLESS allows managing pre-bias startup
■ Preliminary of protection
■ Oscillator internally fixed at 100kHz, externally
adjustable
■ Power good
■ Integrated remote sense buffer
■ VFQFPN36 package with exposed pad
Applications
■ Memory supply for server and workstation MBs
■ High density DC / DC converters
■ High current pol
Description
L6722 implements a three-phase step-down
controller with 120º phase-shift between each
phase with integrated high-current drivers in a
compact VFQFPN36 package with exposed pad.
L6722 manages output voltages down to 0.8V
with ±1% output voltage accuracy over line and
temperature variations. Additional programmable
offset can be added to the reference voltage with
a single external resistor in order to perform
margining tests.
The controller assures fast protection against load
over current and over / under voltage. In case of
over-current the system works in Constant
Current mode until UVP. Preliminary OVP allows
full load protection in case of startup with failed
HS. Feedback-disconnection protection prevents
from damaging the load in case of misconnections
in the remote sense. Pre-bias start-up is also
managed thanks to LSLESS.
Combined use of DCR and RdsON current
sensing assures precision in voltage positioning
(by reading droop current across inductors DCR)
and safe current sharing and OCP per each
phase (by reading the current across LS RdsON).
Droop function can be anyway disabled to
perform precise and load-insensitive regulation.
VFQFPN36
www.st.com
Order codes
Part number Package Packing
L6722
VFQFPN36 Tube
L6722TR
VFQFPN36 Tape & Reel
Obsolete Product(s) - Obsolete Product(s)
Obsolete Product(s) - Obsolete Product(s)
Obsolete Product(s) - Obsolete Product(s)
L6722
2/34
Contents
1 Typical application circuit and block diagram . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Pins description and connection diagrams . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3 Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4 Device description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5 Driver section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1 Power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6 Current sharing loop and current reading . . . . . . . . . . . . . . . . . . . . . . . . 16
7 Output voltage positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.1 Offset and margining-mode (optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.2 Droop function (optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.3 Maximum duty cycle limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8 Soft start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1 Low-side-less startup for pre-bias output . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
9 Output voltage monitor and protections . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.1 Under voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.2 Over voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.3 Preliminary over voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.4 Feedback disconnection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
9.5 PGOOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Obsolete Product(s) - Obsolete Product(s)
Obsolete Product(s) - Obsolete Product(s)
L6722
3/34
9.6 Over-current protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
10 Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
11 System control loop compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
11.1 Compensation network guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
12 Layout guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
12.1 Power components and connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
12.2 Small signal components and connections . . . . . . . . . . . . . . . . . . . . . . . . . . 30
13 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Obsolete Product(s) - Obsolete Product(s)
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P34

L6722TR

Mfr. #:
Buy L6722TR
Manufacturer:
STMicroelectronics
Description:
Switching Controllers 3 Phase Controller
Lifecycle:
New from this manufacturer.
Delivery:
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