Step-Down Controller. LTC3819 Datasheet

LTC3819 Controller. Datasheet pdf. Equivalent

Part LTC3819
Description Step-Down Controller
Feature www.DataSheet4U.com LTC3819 2-Phase, High Efficiency, Step-Down Controller for Sun Server CPUs FEA.
Manufacture Linear Technology
Datasheet
Download LTC3819 Datasheet




LTC3819
www.DataSheet4U.com
LTC3819
2-Phase, High Efficiency,
Step-Down Controller for
Sun Server CPUs
FEATURES
Output Stages Operate Antiphase Reducing Input
and Output Capacitance Requirements and Power
Supply Induced Noise
Dual Input Supply Capability for Load Sharing
5-Bit SUN CPU VID Code:
VOUT = 1.025V to 1.4125V
±1% Output Voltage Accuracy
True Remote Sensing Differential Amplifier
Power Good Output Voltage Monitor
Supports Active Voltage Positioning
Current Mode Control Ensures Current Sharing
OPTI-LOOP® Compensation Minimizes COUT
Three Operational Modes: PWM, Burst and Cycle Skip
Programmable Fixed Frequency: 150kHz to 300kHz
Wide VIN Range: 4V to 36V Operation
Adjustable Soft-Start Current Ramping
Internal Current Foldback and Short-Circuit Shutdown
Overvoltage Soft Latch Eliminates Nuisance Trips
Available in 36-LUead Narrow (0.209) SSOP Package
APPLICATIO S
Sun™ Server CPU Supply
, LTC and LT are registered trademarks of Linear Technology Corporation. OPTI-LOOP
and Burst Mode are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents including
5481178, 5929620, 6177787, 6144194, 6100678, 5408150, 6580258, 6304066, 5705919.
DESCRIPTIO
The LTC®3819 is a 2-phase, VID programmable, synchro-
nous step-down switching regulator controller that drives
two N-channel external power MOSFET stages in a fixed fre-
quency architecture. The 2-phase controller drives its two
output stages out of phase at frequencies up to 300kHz to
minimize the RMS ripple currents in both input and output
capacitors. The 2-phase technique effectively multiplies the
fundamental frequency by two, improving transient re-
sponse while operating each channel at an optimum fre-
quency for efficiency. Thermal design is also simplified.
An operating mode select pin (FCB) can be used to select
among three modes including Burst Mode® operation for
highest efficiency. An internal differential amplifier provides
true remote sensing of the regulated supply’s positive and
negative output terminals as required in high current ap-
plications.
The RUN/SS pin provides soft-start and optional timed,
short-circuit shutdown. Current foldback limits MOSFET
dissipation during short-circuit conditions when the
overcurrent latchoff is disabled. OPTI-LOOP compensation
allows the transient response to be optimized for a wide
range of output capacitors and ESR values.
TYPICAL APPLICATIO
0.1µF FCB
VIN TG1
S
220pF
3.3k
RUN/SS
BOOST1
SW1
LTC3819
ITH BG1
0.47µF
S
SGND
PGND
PGOOD
5 VID BITS VID0–VID4
SENSE1+
SENSE1
TG2
EAIN
ATTENOUT
BOOST2
SW2
0.47µF
ATTENIN
BG2
VDIFFOUT
VOS–
VOS+
INTVCC
SENSE2+
SENSE2
10µF
10µF
35V
×6
1µH
D1
0.002
1µH
D2
0.002
Figure 1. High Current Dual Phase Step-Down Converter
VIN
5V TO 28V
VDD_CORE
1.025V TO 1.4125V
45A
+ COUT
270µF
2V
×4
3716 F01
3819f
1



LTC3819
www.DataSheet4U.com
LTC3819
ABSOLUTE AXI U RATI GS
(Note 1)
Input Supply Voltage (VIN).........................36V to – 0.3V
Topside Driver Voltages (BOOST1,2) .........42V to – 0.3V
Switch Voltage (SW1, 2) .............................36V to – 5 V
SENSE1+, SENSE2 +, SENSE1,
SENSE2 Voltages ................... (1.1)INTVCC to – 0.3V
EAIN, VOS+, VOS–, EXTVCC, INTVCC, RUN/SS,
VBIAS, ATTENIN, ATTENOUT, PGOOD, NO_CPU,
VID0–VID4, Voltages ...............................7V to – 0.3V
Boosted Driver Voltage (BOOST-SW) ..........7V to – 0.3V
PLLFLTR, PLLIN, VDIFFOUT,
FCB Voltages ................................... INTVCC to – 0.3V
ITH Voltage ................................................2.7V to – 0.3V
Peak Output Current <1µs(TG1, 2, BG1, 2) ................ 3A
INTVCC RMS Output Current ................................ 50mA
Operating Ambient Temperature Range
(Note 2) .............................................. – 40°C to 85°C
Junction Temperature (Note 3) ............................. 125°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
UW U
PACKAGE/ORDER I FOR ATIO
TOP VIEW
RUN/SS
SENSE1+
SENSE1
1
2
3
EAIN 4
PLLFLTR 5
PLLIN 6
FCB 7
ITH 8
SGND 9
VDIFFOUT
VOS–
VOS+
SENSE2
10
11
12
13
SENSE2+ 14
ATTENOUT 15
NO_CPU 16
VID0 17
VID1 18
36 PGOOD
35 TG1
34 SW1
33 BOOST1
32 VIN
31 BG1
30 EXTVCC
29 INTVCC
28 PGND
27 BG2
26 BOOST2
25 SW2
24 TG2
23 ATTENIN
22 VBIAS
21 VID4
20 VID3
19 VID2
ORDER PART
NUMBER
LTC3819EG
G PACKAGE
36-LEAD PLASTIC SSOP
TJMAX = 125°C, θJA = 85°C/W
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 15V, VBIAS = 5V, VRUN/SS = 5V unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Main Control Loop
VEAIN
VSENSEMAX
IINEAIN
VLOADREG
Regulated Feedback Voltage
Maximum Current Sense Threshold
Feedback Current
Output Voltage Load Regulation
VREFLNREG
VFCB
IFCB
VBINHIBIT
Reference Voltage Line Regulation
Forced Continuous Threshold
Forced Continuous Current
Burst Inhibit (Constant Frequency)
Threshold
ITH Voltage = 1.2V; Measured at VEAIN (Note 4)
(Note 4)
(Note 4)
Measured in Servo Loop, ITH Voltage: 1.2V to 0.7V
Measured in Servo Loop, ITH Voltage: 1.2V to 2V
VIN = 3.6V to 30V (Note 4)
0.594
62
0.57
Measured at FCB pin
0.600
75
–5
0.1
– 0.1
0.002
0.6
– 0.17
4.3
0.606
88
– 50
0.5
– 0.5
0.02
0.63
–1
4.8
V
mV
nA
%
%
%/V
V
µA
V
VOVL
UVLO
Output Overvoltage Threshold
Undervoltage Lockout
Measured at VEAIN
VIN Ramping Down
0.64 0.66 0.68
3 3.33 4
V
V
3819f
2







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