Switching Regulator. LTC1628-SYNC Datasheet

LTC1628-SYNC Regulator. Datasheet pdf. Equivalent

Part LTC1628-SYNC
Description 2-Phase Synchronous Step-Down Switching Regulator
Feature U U LTC1628-SYNC High Efficiency, 2-Phase Synchronous Step-Down Switching Regulator FEATURES ■ Out.
Manufacture Linear
Datasheet
Download LTC1628-SYNC Datasheet



LTC1628-SYNC
LTC1628-SYNC
High Efficiency, 2-Phase
Synchronous Step-Down Switching Regulator
FEATURES
Out-of-Phase Controllers Reduce Required Input
Capacitance and Power Supply Induced Noise
OPTI-LOOP® Compensation Minimizes COUT
Dual N-Channel MOSFET Synchronous Drive
±1% Output Voltage Accuracy
Power Good Output Voltage Monitor
Phase-Lockable Fixed Frequency 150kHz to 300kHz
Wide VIN Range: 3.5V to 36V Operation
Very Low Dropout Operation: 99% Duty Cycle
Adjustable Soft-Start Current Ramping
Foldback Output Current Limiting
Latched Short-Circuit Shutdown with Defeat Option
Output Overvoltage Protection
Remote Output Voltage Sense
Low Shutdown IQ: 20µA
5V and 3.3V Standby Regulators
Selectable Constant Frequency or Burst Mode®
Operation
Small 28-Lead SSOP Package
U
APPLICATIO S
Notebook and Palmtop Computers, PDAs
Telecom Systems
Battery-Operated Digital Devices
DC Power Distribution Systems
DESCRIPTIO
The LTC®1628-SYNC is a high performance dual step-
down switching regulator controller that drives all
N-channel synchronous power MOSFET stages. A con-
stant frequency current mode architecture allows phase-
lockable frequency of up to 300kHz. Power loss and noise
due to the ESR of the input capacitors are minimized by
operating the two controller output stages out of phase.
OPTI-LOOP compensation allows the transient response
to be optimized over a wide range of output capacitance and
ESR values. The precision 0.8V reference and power good
output indicator are compatible with future microproces-
sor generations, and a wide 3.5V to 30V (36V maximum)
input supply range encompasses all battery chemistries.
A RUN/SS pin for each controller provides both soft-start
and optional timed, short-circuit shutdown. Current
foldback limits MOSFET dissipation during short-circuit
conditions when overcurrent latchoff is disabled. Output
overvoltage protection circuitry latches on the bottom
MOSFET until VOUT returns to normal. The FCB mode pin
can select among Burst Mode, constant frequency mode
and continuous inductor current mode or regulate a
secondary winding.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode and OPTI-LOOP 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.
TYPICAL APPLICATIO
L1
6.3µH
D1
VOUT1
5V
5A
RSENSE1
0.01
+
COUT1
47µF
6V
SP
R2
105k
1%
+
4.7µF
M1
CB1, 0.1µF
M2
D3
VIN PGOOD INTVCC
TG1 TG2
BOOST1
BOOST2
SW1 SW2
LTC1628-SYNC
BG1 BG2
1µF
D4 CERAMIC
CB2, 0.1µF
M3
M4
fIN
1000pF
PLLIN
SENSE1+
SENSE1
PGND
SENSE2+
SENSE2
1000pF
VOSENSE1
VOSENSE2
ITH1 ITH2
R1
CC1
220pF
RUN/SS1 SGND RUN/SS2
CC2
220pF
20k
1%
RC1
15k
CSS1
0.1µF
CSS2
0.1µF
RC2
15k
R3
20k
1%
VIN
CIN 5.2V TO 28V
22µF
50V
CERAMIC
L2
6.3µH
D2
R4
63.4k
1%
RSENSE2
0.01
VOUT2
3.3V
5A
COUT
56µF
6V
SP
+
M1, M2, M3, M4: FDS6680A
Figure 1. High Efficiency Dual 5V/3.3V Step-Down Converter
1628 F01
1628syncfa
1



LTC1628-SYNC
LTC1628-SYNC
ABSOLUTE AXI U RATI GS
(Note 1)
Input Supply Voltage (VIN).........................36V to – 0.3V
Top Side Driver Voltages
(BOOST1, BOOST2) ...................................42V to – 0.3V
Switch Voltage (SW1, SW2) .........................36V to – 5V
INTVCC, EXTVCC, RUN/SS1, RUN/SS2, (BOOST1-SW1),
(BOOST2-SW2), PGOOD .............................7V to – 0.3V
SENSE1+, SENSE2 +, SENSE1,
SENSE2 Voltages ........................ (1.1)INTVCC to – 0.3V
PLLIN, PLLFLTR, FCB, Voltage ............ INTVCC to – 0.3V
ITH1, ITH2, VOSENSE1, VOSENSE2 Voltages ... 2.7V to – 0.3V
Peak Output Current <10µs (TG1, TG2, BG1, BG2) ... 3A
INTVCC Peak Output Current ................................ 50mA
Operating Temperature Range
LTC1628CG-SYNC ................................... 0°C to 85°C
LTC1628IG-SYNC ............................... – 40°C to 85°C
Junction Temperature (Note 2) ............................. 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/SS1
SENSE1+
SENSE1
1
2
3
VOSENSE1 4
PLLFLTR 5
PLLIN 6
FCB 7
ITH1 8
SGND 9
3.3VOUT 10
ITH2 11
VOSENSE2 12
SENSE213
SENSE2+ 14
28 PGOOD
27 TG1
26 SW1
25 BOOST1
24 VIN
23 BG1
22 EXTVCC
21 INTVCC
20 PGND
19 BG2
18 BOOST2
17 SW2
16 TG2
15 RUN/SS2
G PACKAGE
28-LEAD PLASTIC SSOP
TJMAX = 125°C, θJA = 95°C/W
*PGOOD ON THE LTC1628-SYNC
ORDER PART NUMBER
LTC1628CG-SYNC
LTC1628IG-SYNC
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, VRUN/SS1, 2 = 5V unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Main Control Loops
VOSENSE1, 2
IVOSENSE1, 2
VREFLNREG
VLOADREG
Regulated Feedback Voltage
Feedback Current
Reference Voltage Line Regulation
Output Voltage Load Regulation
gm1, 2
gmGBW1, 2
IQ
VFCB
IFCB
VBINHIBIT
Transconductance Amplifier gm
Transconductance Amplifier GBW
Input DC Supply Current
Normal Mode
Shutdown
Forced Continuous Threshold
Forced Continuous Pin Current
Burst Inhibit (Constant Frequency)
Threshold
(Note 3); ITH1, 2 Voltage = 1.2V
(Note 3)
VIN = 3.6V to 30V (Note 3)
(Note 3)
Measured in Servo Loop; ITH Voltage = 1.2V to 0.7V
Measured in Servo Loop; ITH Voltage = 1.2V to 2.0V
ITH1, 2 = 1.2V; Sink/Source 5uA; (Note 3)
ITH1, 2 = 1.2V; (Note 3)
(Note 4)
VIN = 15V; EXTVCC Tied to VOUT1; VOUT1 = 5V
VRUN/SS1, 2 = 0V, VSTBYMD = Open;
VFCB = 0.85V
Measured at FCB Pin
0.792
0.76
– 0.30
0.800
–5
0.002
0.1
– 0.1
1.3
3
350
20
0.800
– 0.18
4.3
0.808
– 50
0.02
0.5
– 0.5
35
0.84
– 0.1
4.8
V
nA
%/V
%
%
mmho
MHz
µA
µA
V
µA
V
2
1628syncfa





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