LTC3738CUHF Linear Technology, LTC3738CUHF Datasheet

IC CTRLR SW REG 3PH STPDWN 38QFN

LTC3738CUHF

Manufacturer Part Number
LTC3738CUHF
Description
IC CTRLR SW REG 3PH STPDWN 38QFN
Manufacturer
Linear Technology
Datasheet

Specifications of LTC3738CUHF

Applications
Controller, Intel VRM9, VRM10
Voltage - Input
3.8 ~ 36 V
Number Of Outputs
1
Voltage - Output
0.84 ~ 1.6 V
Operating Temperature
0°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
38-QFN
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LTC3738CUHF
Manufacturer:
LT
Quantity:
10 000
Part Number:
LTC3738CUHF
Manufacturer:
LINEAR/凌特
Quantity:
20 000
FEATURES
APPLICATIO S
TYPICAL APPLICATIO
U.S. Patent Numbers: 5481178, 5994885, 5929620, 6177787, 6144194, 6580258, 6462525,
6593724, 6674274, 6100678 pending on AVP technique.
3-Phase Controller with Onboard MOSFET Drivers
Programmable Active Voltage Positioning (AVP)
with True Current Sensing
Programmable External Thermal Detection or
Internal Thermal Sensing
Precise Output Current Matching Optimizes
Thermal Performance and Solution Size
Supports Starting into Precharged V
Differential Amplifier Accurately Senses V
PWM, Pulse Skip and Stage Shedding
Synchronizable
210kHz to 530kHz Per Phase, Fixed Frequency
Output Power Good Indicator with Adaptive Blanking
Adjustable Soft-Start Current Ramping
Short-Circuit Shutdown Timer with Defeat Option
OPTI-LOOP
38-Lead (5mm × 7mm) QFN Package
High Performance Notebook Computers
Servers, Desktop Computers and Workstations
®
Compensation Minimizes C
U
MODE SELECTION/SYNC IN
POWER GOOD INDICATOR
5V
VR HOT INDICATOR
THERMAL INPUT
ON/OFF
10µF
0.1µF
U
5k
100pF
SW3 SW2 SW1
680pF
OUTS
TM
0.1µF
Operation
OUT
OUT
VRM10 Step-Down Controller
V
BOOST1
BOOST2
BOOST3
PGOOD
FCB/SYNC
PLLFLTR
TSNS
VR_HOTB
OUTEN
I
SS
SGND
EAIN
AVP
IN
IN
TH
CC
+
LTC3738
VID0-VID5
SENSE1
SENSE1
SENSE2
SENSE2
SENSE3
SENSE3
PGND
SW1
SW2
SW3
BG1
BG2
BG3
TG1
TG2
TG3
+
+
+
DESCRIPTIO
The LTC
ing regulator controller that drives all N-channel external
power MOSFET stages in a phase-lockable, fixed fre-
quency architecture. The 3-phase technique effectively
triples the fundamental frequency, improving transient
response while operating each controller at an optimal
frequency for efficiency and ease of thermal design. Light
load efficiency is optimized by using a choice of output
Stage Shedding or Pulse Skip mode technology.
The LTC3738 also allows users to program load slope via
a resistor for AVP control. Both external and internal
thermal sensing are available from the on-chip thermal
detector and comparator.
A differential amplifier provides sensing of both the high
and low sides of the output voltage.
Soft-start and a defeatable, timed short-circuit shutdown
protect the MOSFETs and the load. A foldback current
circuit also provides protection for the external MOSFETs
under short-circuit or overload conditions. An all- “1” VID
detector turns off the regulator after a 1µs timeout.
OPTI-LOOP is a registered trademark of Linear Technology Corporation.
Stage Shedding is a trademark of Linear Technology Corporation.
for Intel VRM9/VRM10 with
Active Voltage Positioning
, LTC and LT are registered trademarks of Linear Technology Corporation.
6 VID BITS
V
V
IN
IN
3-Phase Buck Controller
0.8µH
0.8µH
0.8µH
®
3738 is a 3-phase synchronous step-down switch-
0.002Ω
0.002Ω
0.002Ω
U
+
3738 TA01
+
470µF
×4
V
0.8375V TO 1.6000V
22µF
×2
OUT
V
5V TO 28V
IN
LTC3738
1
3738f

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LTC3738CUHF Summary of contents

Page 1

... MOSFETs under short-circuit or overload conditions. An all- “1” VID detector turns off the regulator after a 1µs timeout. , LTC and LT are registered trademarks of Linear Technology Corporation. OPTI-LOOP is a registered trademark of Linear Technology Corporation. Stage Shedding is a trademark of Linear Technology Corporation. ...

Page 2

... FCB Bias Current FCB 2 U PACKAGE/ORDER I FOR ATIO ) .... 7V to –0. ..................... 5A N FCB/SYNC to –0.3V CC ORDER PART LTC3738CUHF Consult LTC Marketing for parts specified with wider operating temperature ranges. The ● denotes the specifications which apply over the full operating = 25° OUTEN SS CONDITIONS (Note 3) ...

Page 3

ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER V Pulse Skip Threshold PSTH UVR Undervoltage SS Reset I Input DC Supply Current Q Normal Mode Shutdown V OUTEN Pin ON Threshold OUTEN I Soft-Start Charge Current SS ...

Page 4

LTC3738 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER Oscillator and Phase-Locked Loop f Nominal Frequency NOM f Lowest Frequency LOW f Highest Frequency HIGH R FCB Clock Input Threshold FCB I Phase Detector Output Current PLL ...

Page 5

W U TYPICAL PERFOR A CE CHARACTERISTICS Efficiency vs I OUT 100 FCB/SYNC OPEN FCB/SYNC FCB/SYNC 12V 1.2V 10 ...

Page 6

LTC3738 W U TYPICAL PERFOR A CE CHARACTERISTICS Short-Circuit Arming and Latchoff vs Temperature 5.0 4.5 4.0 ARMING 3.5 LATCHOFF 3.0 2.5 2.0 –45 –30 – TEMPERATURE (°C) 3738 G10 SS Pull-Up Current ...

Page 7

W U TYPICAL PERFOR A CE CHARACTERISTICS Maximum Current Threshold Mismatch vs Temperature 3.0 2.5 2.0 1.5 1.0 0.5 0 – –30 –15 TEMPERATURE (°C) Shed Mode at 1A, Light Load Current V OUT 10mV/DIV V SW1 ...

Page 8

LTC3738 CTIO S FCB/SYNC (Pin 1): Forced Continuous Control Input. The voltage applied to this pin sets the operating mode of the controller. The forced continuous current mode is active when the applied voltage is ...

Page 9

CTIO S SW1, SW2, SW3 (Pins 30, 27, 21): Switch Node Connec- tions to Inductors. Voltage swing at these pins is from a Schottky diode (external) voltage drop below ground to V (where V is ...

Page 10

LTC3738 CTIO AL DIAGRA PGOOD 2.4V 2.5µA FCB/SYNC + FCB – 0.6V PHASE DET PLLFLTR OSCILLATOR – IN 80k 80k – 80k 80k R PRE-AVP + + – SENSE1 ...

Page 11

U OPERATIO (Refer to Functional Diagram) Main Control Loop The IC uses a constant frequency, current mode step- down architecture. During normal operation, each top MOSFET is turned on each cycle when the oscillator sets the RS latch, and turned ...

Page 12

LTC3738 U OPERATIO (Refer to Functional Diagram) Tying the FCB/SYNC pin to ground will force continuous current operation. This is the least efficient operating mode, but may be desirable in certain applications. The output can source or sink current in ...

Page 13

U OPERATIO (Refer to Functional Diagram) Start-Up The start-up of the LTC3738 is controlled by the voltage ramp on the SS pin. The start-up is not completed until the short-circuit arming latch is enabled. During start-up, the foldback current limit ...

Page 14

LTC3738 U U APPLICATIO S I FOR ATIO The basic application circuit is shown on the first page of this data sheet. External component selection is driven by the load requirement, and normally begins with the selec- tion of an ...

Page 15

U U APPLICATIO S I FOR ATIO 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 DUTY FACTOR (V /V OUT Figure 3. Normalized Peak Output Current vs Duty Factor [I = ...

Page 16

LTC3738 U U APPLICATIO S I FOR ATIO MILLER EFFECT – Q )/V MILLER Figure 4. Gate Charge Characteristic The curve is generated by forcing a constant input ...

Page 17

U U APPLICATIO S I FOR ATIO The Schottky diodes shown in the Typical Application on the first page of this data sheet conduct during the dead time between the conduction of the two large power MOSFETs. This prevents the ...

Page 18

LTC3738 U U APPLICATIO S I FOR ATIO applied. Physically, if the capacitance value changes due to applied voltage change, there is a concommitant piezo effect which results in radiating sound! A load that draws varying current at an audible ...

Page 19

U U APPLICATIO S I FOR ATIO V Decoupling CC The V pin supplies power not only to the internal circuits CC of the controller but also to the top and bottom gate drivers and therefore must be bypassed very ...

Page 20

LTC3738 U U APPLICATIO S I FOR ATIO Table 1. VRM9 VID Table PROCESSOR PINS (0 = L0W HIGH) VID4 VID3 VID2 VID1 ...

Page 21

Table 2. VRM10 VID Table PROCESSOR PINS (0 = LOW HIGH) VID4 VID3 VID2 VID1 VID0 ...

Page 22

LTC3738 U U APPLICATIO S I FOR ATIO given adequate time to charge up the output capacitor and provide full load current, the SS capacitor is used for a short-circuit timer. If the output voltage falls to less than 62.5% ...

Page 23

U U APPLICATIO S I FOR ATIO Undervoltage Reset In the event that the input power source to the IC (V drops below 4V, the SS capacitor will be discharged to ground and the controller will be shut down. When ...

Page 24

LTC3738 U U APPLICATIO S I FOR ATIO If the duty cycle falls below what can be accommodated by the minimum on-time, the IC will begin to skip every other cycle, resulting in half-frequency operation. The output voltage will continue ...

Page 25

U U APPLICATIO S I FOR ATIO alter its delivery of current quickly enough to prevent this sudden step change in output voltage if the load switch resistance is low and it is driven quickly than 2% of ...

Page 26

LTC3738 U U APPLICATIO S I FOR ATIO PC Board Layout Checklist When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the IC. These items are also illustrated graphically in the ...

Page 27

U U APPLICATIO S I FOR ATIO BOLD LINES INDICATE HIGH, SWITCHING CURRENT LINES. KEEP LINES TO A MININMUM LENGTH SW1 R SENSE1 D1 L2 SW2 R SENSE2 D2 L3 ...

Page 28

LTC3738 U U APPLICATIO S I FOR ATIO SINGLE PHASE CIN I COUT TRIPLE PHASE SW1 V SW2 V SW3 CIN I COUT Figure 11. Single and Polyphase Current ...

Page 29

U U APPLICATIO S I FOR ATIO result that is within 10% to 20% of the final application. The temperature of the MOSFET’s die temperature may require interative calculations if one is not familiar typical performance. A maximum operating junction ...

Page 30

LTC3738 U TYPICAL APPLICATIO VID2 IN V ON/0FF VID1 IN CC 100pF 51k OUTEN VID2 VID1 FCB/SYNC 10k PLLFLTR R – AVP IN 100Ω 30pF AVP R 220Ω PREAVP EAIN 10Ω × SENSE1 (EXPOSED PAD ...

Page 31

... DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. U UHF Package 38-Lead Plastic QFN (7mm × ...

Page 32

... Single Phase DC/DC Controller for Intel IMVP-4 Compatible Processors LTC3735 2-Phase DC/DC Controller for Pentium (Centrino) Processors trademark of Linear Technology Corporation. Pentium is a registered trademark of Intel Corporation. SENSE Opteron is a trademark of AMD Corporation. Linear Technology Corporation 32 1630 McCarthy Blvd., Milpitas, CA 95035-7417 ...

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