IC STP-DWN CNTRLR W/OPAMP 28SSOP

LTC3714EG#PBF

Manufacturer Part NumberLTC3714EG#PBF
DescriptionIC STP-DWN CNTRLR W/OPAMP 28SSOP
ManufacturerLinear Technology
LTC3714EG#PBF datasheet
 


Specifications of LTC3714EG#PBF

ApplicationsController, Intel Pentium®Voltage - Input4 ~ 36 V
Number Of Outputs1Voltage - Output0.6 ~ 1.75 V
Operating Temperature-40°C ~ 85°CMounting TypeSurface Mount
Package / Case28-SSOPPrimary Input Voltage36V
No. Of Outputs1Output Voltage1.75V
Output Current20ANo. Of Pins28
Operating Temperature Range-40°C To +85°CMslMSL 1 - Unlimited
Rohs CompliantYesLead Free Status / RoHS StatusLead free / RoHS Compliant
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FeaTures
High Efficiency: Up to 95%
n
1.5A/1A Guaranteed Minimum Output Current
n
Synchronizable to External Clock
n
No Schottky Diodes Required
n
Programmable Frequency Operation: 1.5MHz or
n
Adjustable From 0.6MHz to 4MHz
Low R
Internal Switches
n
DS(ON)
Short-Circuit Protected
n
V
: 2.25V to 5.5V
n
IN
Current Mode Operation for Excellent Line and Load
n
Transient Response
125µA Quiescent Current in Sleep Mode
n
Ultralow Shutdown Current: I
< 1µA
n
Q
Low Dropout Operation: 100% Duty Cycle
n
Power Good Output
n
Phase Pin Selects 2nd Channel Phase Relationship
n
with Respect to 1st Channel
Internal Soft-Start with Individual Run Pin Control
n
Available in Small Thermally Enhanced
n
(5mm × 3mm) DFN and 20-Lead TSSOP Packages
applicaTions
GPS/Navigation
n
Digital Cameras
n
PC Cards
n
Wireless and DSL Modems
n
General Purpose Point of Load DC/DC
n
Typical applicaTion
V
IN
2.5V TO 5.5V
10µF
V
IN
FREQ
1.5µH
V
OUT1
1.8V
SW2
SW1
22pF
1.5A
RUN2
V
RUN1
IN
LTC3417A
511k
V
V
FB2
FB1
47µF
412k
I
I
TH2
TH1
5.9k
GND
2200pF
1.5A/1A 4MHz Step-Down
DescripTion
The LTC
3417A is a dual constant frequency, synchronous
®
step-down DC/DC converter. Intended for medium power
applications, it operates from a 2.25V to 5.5V input volt-
age range and has a constant programmable switching
frequency, allowing the use of tiny, low cost capacitors
and inductors 2mm or less in height. Each output voltage
is adjustable from 0.8V to 5V. Internal, synchronous, low
R
power switches provide high efficiency without
DS(ON)
the need for external Schottky diodes.
A user selectable mode input allows the user to trade
off ripple voltage for light load efficiency. Burst Mode
operation provides high efficiency at light loads, while
Pulse Skip mode provides low ripple noise at light loads.
A phase mode pin allows the second channel to operate
in-phase or 180° out-of-phase with respect to channel 1.
Out-of-phase operation produces lower RMS current on V
and thus a lower RMS derating on the input capacitor.
To further maximize battery life, the P-channel MOSFETs
are turned on continuously in dropout (100% duty cycle)
and both channels draw a total quiescent current of only
125µA. In shutdown, the device draws <1µA.
L, LT, LTC, LTM and Burst Mode are registered trademarks and Hot Swap and ThinSOT are
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners. Protected by U.S. Patents including 5481178, 6580258, 6304066, 6127815,
6498466, 6611131, 6144194.
100
2.2µH
V
OUT2
2.5V
22pF
1A
V
IN
866k
22µF
412k
2.87k
6800pF
3417 TA01
LTC3417A
Dual Synchronous
DC/DC Regulator
OUT2 Efficiency
(Burst Mode Operation)
10
REFER TO FIGURE 4
95
EFFICIENCY
1
90
0.1
85
0.01
80
POWER LOSS
0.001
75
V
= 3.6V
IN
V
= 2.5V
OUT
FREQ = 1MHz
0.0001
70
0.001
0.01
0.1
1
LOAD CURRENT (A)
3417 TA01a
®
IN
3417afc
1

LTC3714EG#PBF Summary of contents

  • Page 1

    ... In shutdown, the device draws <1µA. L, LT, LTC, LTM and Burst Mode are registered trademarks and Hot Swap and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 6580258, 6304066, 6127815, 6498466, 6611131, 6144194 ...

  • Page 2

    LTC3417A absoluTe MaxiMuM raTings Voltages ...................................... – 0. IN1 IN2 SYNC/MODE, SW1, SW2, RUN1, RUN2 PHASE, FREQ, FB1 FB2 Voltages............... – 0. TH1 TH2 V – ...

  • Page 3

    T SYMBOL PARAMETER I Input DC Supply Current (Note 4) S Active Mode Half Active Mode (V = 0V, 1.5A Only) RUN2 Half Active Mode (V = 0V, 1A Only) RUN1 Both ...

  • Page 4

    LTC3417A Typical perForMance characTerisTics OUT1 Burst Mode Operation V OUT 20mV/DIV I L 250mA/DIV V = 3.6V 2µs/DIV 1.8V OUT I = 100mA LOAD REFER TO FIGURE 4 OUT2 Burst Mode Operation V OUT 20mV/DIV I L ...

  • Page 5

    Typical perForMance characTerisTics OUT2 Efficiency (Pulse Skipping Mode) 100 I = 250mA LOAD 800mA LOAD 2.5V OUT REFER TO FIGURE 2.5 3 3.5 4 4.5 ...

  • Page 6

    LTC3417A pin FuncTions (DFN/TSSOP) RUN1 (Pin 1/Pin 2): Enable for 1.5A Regulator. When at Logic 1, 1.5A regulator is running. When at 0V, 1.5A regulator is off. When both RUN1 and RUN2 are at 0V, the part is in shutdown. ...

  • Page 7

    FuncTional DiagraM 1.5A REGULATOR V FB1 0.752V 0.848V RUN1 VOLTAGE REFERENCE RUN2 SYNC/MODE 0.848V 0.752V V FB2 1A REGULATOR I TH1 I TH LIMIT + – – – + LOGIC – V IN2 – LOGIC + ...

  • Page 8

    LTC3417A operaTion The LTC3417A uses a constant frequency, current mode architecture. Both channels share the same clock frequency. The PHASE pin sets whether the channels are running in-phase or out of phase. The operating frequency is de- termined by connecting ...

  • Page 9

    A general LTC3417A application circuit is shown in Figure 4. External component selection is driven by the load requirement, and begins with the selection of the inductors L1 and L2. Once L1 and L2 are chosen ...

  • Page 10

    LTC3417A applicaTions inForMaTion Inductor Core Selection Different core materials and shapes will change the size/ current relationship of an inductor. Toroid or shielded pot cores in ferrite or permalloy materials are small and don’t radiate much energy, but generally cost ...

  • Page 11

    When then the equation simplifies to 1– RMS – OUT OUT ...

  • Page 12

    LTC3417A applicaTions inForMaTion is given to ripple current ratings and long term reliability. Ceramic capacitors have the lowest ESR and cost but also have the lowest capacitance density, high voltage and temperature coefficient and exhibit audible piezoelectric effects. In addition, ...

  • Page 13

    V RUN 2V/DIV V OUT 1V/DIV I L 1A/DIV V = 3.6V 200µs/DIV 1.8V OUT R = 0.9 L Figure 2. Digital Soft-Start OUT1 I over 1024 clock cycles, as can be seen in Figures ...

  • Page 14

    ... For a detailed explanation of optimizing the compensation components, including a review of control loop theory, refer to Linear Technology Application Note 76. Although a buck regulator is capable of providing the full output current in dropout, it should be noted that as the ...

  • Page 15

    V to ground. The resulting charge over the switching IN period is a current out of V that is typically much larger IN than the DC ...

  • Page 16

    LTC3417A applicaTions inForMaTion Remembering that the above junction temperature is obtained from 25°C, we might recalculate DS(ON) the junction temperature based on a higher R it increases with temperature. However, we can safely as- sume that the ...

  • Page 17

    V IN 2.25V TO 5.5V V OUT1 1.8V C1 22pF 1.5A R1 511k C OUT1 47µF L1: MIDCOM DUS-5121-1R5R C : KEMET C1210C226K8PAC OUT1 Figure 4. 1.8V at 1.5A/2. Step-Down Regulators ...

  • Page 18

    LTC3417A applicaTions inForMaTion Board Layout Considerations When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the LTC3417A. These items are also illustrated graphically in the layout diagram of Figure 5. Check ...

  • Page 19

    DescripTion 3.50 ±0.05 1.65 ±0.05 2.20 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS PIN 1 TOP MARK (SEE NOTE 6) 0.200 REF NOTE: 1. DRAWING PROPOSED TO BE MADE VARIATION OF VERSION (WJED-1) IN JEDEC PACKAGE OUTLINE ...

  • Page 20

    LTC3417A package DescripTion 6.60 ±0.10 4.50 ±0.10 SEE NOTE 4 RECOMMENDED SOLDER PAD LAYOUT 4.30 – 4.50* (.169 – .177) 0.09 – 0.20 0.50 – 0.75 (.0035 – .0079) (.020 – .030) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS 2. DIMENSIONS ARE ...

  • Page 21

    ... Changed 100µA to 125µA in the last paragraph of the Description section. 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 22

    ... V = 0.8V 380µA, IN OUT(MIN 2.5V to 5.5V 2.4V 25µA, IN OUT(MIN 2.5V to 5.5V 2.4V 25µA, IN OUT(MIN 2.4V to 5.5V 2.4V 28µA, IN OUT(MIN 2.5V to 5.5V 0.6V 32µA, IN OUT(MIN 2.5V to 5.5V 0.6V 40µA, IN OUT(MIN) Q 3417afc LT 0311 REV C • PRINTED IN USA  LINEAR TECHNOLOGY CORPORATION 2006 ...