LTC3770EUH#TR Linear Technology, LTC3770EUH#TR Datasheet

LTC3770EUH#TR

Manufacturer Part Number
LTC3770EUH#TR
Description
Manufacturer
Linear Technology
Datasheet

Specifications of LTC3770EUH#TR

Lead Free Status / RoHS Status
Not Compliant

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
LTC3770EUH#TRLTC3770EUH
Manufacturer:
LT
Quantity:
10 000
Company:
Part Number:
LTC3770EUH#TRLTC3770EUH
Manufacturer:
LINEAR/凌特
Quantity:
20 000
Company:
Part Number:
LTC3770EUH#TRLTC3770EUH#PBF
Manufacturer:
LINEAR
Quantity:
20
Company:
Part Number:
LTC3770EUH#TRPBF
Manufacturer:
LT
Quantity:
7
Company:
Part Number:
LTC3770EUH#TRPBF
Manufacturer:
LINEAR/凌特
Quantity:
20 000
APPLICATIONS
TYPICAL APPLICATION
FEATURES
n
n
n
n
n
n
n
n
n
n
n
n
n
n
n
n
n
n
n
n
1000pF
0.01μF
Wide V
±0.67% 0.6V Reference Voltage
Output Voltage Tracking Capability
Programmable Margining
Sense Resistor Optional
True Current Mode Control
2% to 90% Duty Cycle at 200kHz
t
Phase-Locked Loop Frequency Synchronization
Powerful Dual N-Channel MOSFET Driver
Adjustable Cycle-by-Cycle Current Limit
Adjustable Switching Frequency
Programmable Soft-Start
Current Foldback Protection (Disabled at Start-Up)
Output Overvoltage Protection
Micropower Shutdown: I
Power Good Output Voltage Monitor
Tracks the Reference Input Pin
Available in (5mm × 5mm) QFN and 28-Lead
SSOP Packages
Distributed Power Systems
Server Power Supply
ON(MIN)
0.1μF
V
OUT
10k
10k
10k
82k
IN
PGOOD
MARGIN
PLLFLTR
PLLIN
TRACK/SS
I
SGND
RUN
V
V
V
V
MPGM
TH
≤ 100ns
ON
RNG
REFOUT
REFIN
High Effi ciency Step-Down Converter
Range: 4V to 32V
LTC3770
SENSE
SENSE
INTV
BOOST
DRV
PGND
V
I
V
SW
TG
BG
ON
CC
CC
FB
IN
+
68k
0.22μF
CMDSH-3
4.7μF
Q
< 30μA
Si4884
Si4874
1.8μH
3770 TA01
B340A
95.3k
30.1k
+
10μF
35V
x3
180μF
4V
x2
V
5V TO 28V
V
2.5V
10A
IN
OUT
DESCRIPTION
The LTC
regulator controller with output voltage up/down tracking
capability and voltage margining. Its advanced functions
and high accuracy reference are ideal for powering
high performance server, ASIC and computer memory
systems.
The LTC3770 uses a constant on-time, valley current
mode control architecture to deliver very low duty factors
without requiring a sense resistor. The operating frequency
is selected by an external resistor and is compensated for
variations in input supply voltage. An internal phase-locked
loop allows the IC to be synchronized to an external
clock.
Fault protection is provided by an overvoltage comparator
and input undervoltage lockout. The regulator current
limit is user programmable. A wide supply range allows
voltages as high as 32V to be stepped down to as low as
a 0.6V output. Power supply sequencing is accomplished
using an external soft-start timing capacitor.
R
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 5481178, 5487554, 6580258, 6304066, 6476589,
6774611.
SENSE
Margining, Tracking and PLL
Synchronous Controller with
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Fast No R
is a registered trademark of Linear Technology Corporation.
®
3770 is a synchronous step-down switching
Effi ciency and Power Loss vs Load Current
100
95
90
85
80
75
70
65
60
55
50
0.01
V
V
IN
OUT
= 5V
= 2.5V
SENSE
LOAD CURRENT (A)
POWER LOSS
0.1
EFFICIENCY
TM
1
Step-Down
3770 TA01b
LTC3770
10
10
1
0.1
0.01
3770fc
1

Related parts for LTC3770EUH#TR

LTC3770EUH#TR Summary of contents

Page 1

... A wide supply range allows voltages as high as 32V to be stepped down to as low as a 0.6V output. Power supply sequencing is accomplished using an external soft-start timing capacitor. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation registered trademark of Linear Technology Corporation. SENSE All other trademarks are the property of their respective owners ...

Page 2

... TAPE AND REEL LTC3770EG#PBF LTC3770EG#TRPBF LTC3770EUH#PBF LTC3770EUH#TRPBF Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based fi nish parts. For more information on lead free part marking, go to: For more information on tape and reel specifi cations, go to: ...

Page 3

ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are T SYMBOL PARAMETER Main Control Loop I Input DC Supply Current Q Normal Operation Shutdown Supply Current V Feedback Voltage Accuracy (Note Feedback Voltage Line Regulation FB(LINEREG) V Feedback ...

Page 4

LTC3770 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are T SYMBOL PARAMETER Internal V Regulator CC V Internal V Voltage INTVCC CC ΔV Internal V Load Regulation LDO(LOADREG) CC Phased-Locked Loop R PLLIN Input Resistance PLLIN I Phase Detector Output ...

Page 5

TYPICAL PERFORMANCE CHARACTERISTICS On-Time vs Temperature 300 I = 30μA ION VON 250 200 150 100 50 0 –50 – 100 TEMPERATURE (°C) 3770 G04 Error Amplifi Temperature m 1.6 ...

Page 6

LTC3770 TYPICAL PERFORMANCE CHARACTERISTICS Track Up FIGURE 12 CIRCUIT TRACK/ TRACK/SS AND OUT 500mV/DIV V OUT 2V/DIV 250ms/DIV Effi ciency vs Load Current 100 FIGURE 12 CIRCUIT 95 DISCONTINUOUS 90 MODE 85 80 CONTINUOUS 75 ...

Page 7

TYPICAL PERFORMANCE CHARACTERISTICS Current Limit Foldback 160 RNG 140 120 100 0.1 0.2 0 PIN FUNCTIONS (UH Package/G Package) V (Pin 1/Pin 4): Sense Voltage Range Input. The RNG ...

Page 8

LTC3770 PIN FUNCTIONS (UH Package/G Package) sets the ramp rate for the output voltage. When the IC is confi gured to be the slave of two outputs, the V of the master IC is reproduced by a resistor divider and ...

Page 9

PIN FUNCTIONS (UH Package/G Package) V (Pin 31/Pin 2): On-Time Voltage Input. Connecting this ON pin to the output voltage makes the on-time proportional The comparator input defaults to 0.6V when the OUT pin is grounded and ...

Page 10

LTC3770 OPERATION Main Control Loop The LTC3770 is a current mode controller for DC/DC step-down converters. In normal operation, the top MOSFET is turned on for a fi xed interval determined by a one-shot timer OST. When the top MOSFET ...

Page 11

APPLICATIONS INFORMATION The basic LTC3770 application circuit is shown in Figure 12. External component selection is primarily determined by the maximum load current and begins with the selection of the sense resistance and power MOSFET switches. The LTC3770 uses either ...

Page 12

LTC3770 APPLICATIONS INFORMATION The ρ term is a normalization factor (unity at 25°C) T accounting for the signifi cant variation in on-resistance with temperature, typically about 0.4%/°C as shown in Figure 1. For a maximum junction temperature of 100°C, using ...

Page 13

APPLICATIONS INFORMATION When there resistor connected to the I ON the on-time t is theoretically infi nite, which in turn could ON damage the converter. To prevent this, the LTC3770 will detect this fault condition and provide ...

Page 14

LTC3770 APPLICATIONS INFORMATION A reasonable starting point is to choose a ripple current that is about 40 The largest ripple current OUT(MAX) occurs at the highest guarantee that ripple current IN does not exceed ...

Page 15

APPLICATIONS INFORMATION Top MOSFET Driver Supply ( external bootstrap capacitor C connected to the BOOST B pin supplies the gate drive voltage for the topside MOSFET. This capacitor is charged through diode D when the switch ...

Page 16

LTC3770 APPLICATIONS INFORMATION To further limit current in the event of a short circuit to ground, the LTC3770 includes foldback current limiting. If the output falls by more than 60%, then the maximum sense voltage is progressively lowered to about ...

Page 17

APPLICATIONS INFORMATION TIME (7a) Coincident Tracking Figure 7. Two Different Modes of Output Voltage Tracking V OUT1 TRACK/SS2 PIN R4 R2 (8a) Coincident Tracking Setup Figure 8. Setup for Coincident and Ratiometric Tracking ...

Page 18

LTC3770 APPLICATIONS INFORMATION Margining Margining is a way to program the reference voltage to the error amplifi voltage different from the default 0.6V. Margining is useful for customers who want to stress their systems by varying supply ...

Page 19

APPLICATIONS INFORMATION oscillators are identical. At this stable operating point the phase comparator output is open and the fi lter capacitor C holds the voltage. The LTC3770 PLLIN pin must be LP driven from a low impedance source such as ...

Page 20

LTC3770 APPLICATIONS INFORMATION If you make a change and the input current decreases, then the effi ciency has increased. If there is no change in input current, then there is no change in effi ciency. Checking Transient Response The regulator ...

Page 21

APPLICATIONS INFORMATION INTV 100k R7 47k 1 RUN R8 2 51k R5 3 39k 11k 20k 10k 13 CC2 100pF 14 CC1 R ...

Page 22

LTC3770 APPLICATIONS INFORMATION When laying out a printed circuit board, without a ground plane, use the following checklist to ensure proper opera- tion of the controller. • Segregate the signal and power grounds. All small signal components should return to ...

Page 23

... APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...

Page 24

... High Current Synchronous Step-Down Controller IN LTC3731 3-Phase Synchronous Step-Down Controller LTC3778 Low Synchronous Step-Down Controller OUT SENSE Burst Mode is a trademark of Linear Technology Corporation. Linear Technology Corporation 24 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● Typical Application 2.5V/10A Synchronized at 450kHz FCB 31 ...

Related keywords