Datasheet

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LTC4414

4414fc

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.

PowerPath and ThinSOT are trademarks of Linear Technology Corporation. All other

trademarks are the property of their respective owners.

FORWARD VOLTAGE (V)

0.02

CURRENT (A)

8.0

3.6

CONSTANT

4414 TA01b

0.5

CONSTANT

VOLTAGE

SCHOTTKY

DIODE

LTC4414

GND

CTL

SENSE

GATE

STAT

LTC4414

OUT

TO LOAD

STATUS OUTPUT

LOW WHEN POWER

SUPPLY PRESENT

470k

4414 TA01

UPS840

SUP75P03_07

BATTERY

CELL(S)

POWER

SUPPLY

INPUT

Automatic Switchover of Load Between a Battery and a Power Supply

APPLICATIO S

FEATURES

DESCRIPTIO

TYPICAL APPLICATIO

36V, Low Loss PowerPath

Controller for Large PFETs

■

Designed Specifically to Drive Large Q

PFETs

■

Very Low Loss Replacement for Power Supply

OR’ing Diodes

■

3.5V to 36V AC/DC Adapter Voltage Range

■

Minimal External Components

■

Automatic Switching Between DC Sources

■

Low Quiescent Current: 30µA

■

3V to 36V Battery Voltage Range

■

Limited Reverse Battery Protection

■

MOSFET Gate Protection Clamp

■

Manual Control Input

■

Space Saving 8-Lead MSOP Package

■

High Current Power Path Switch

■

Industrial and Automotive Applications

■

Uninterruptable Power Supplies

■

Logic Controlled Power Switch

■

Battery Backup Systems

■

Emergency Systems with Battery Backups

The LTC

4414 controls an external P-channel MOSFET to

create a near ideal diode function for power switchover.

This permits highly efficient OR’ing of multiple power

sources for extended battery life and low self- heating. When

conducting, the voltage drop across the MOSFET is typi-

cally 20mV. For applications with a wall adapter or other aux-

iliary power source, the load is automatically disconnected

from the battery when the auxiliary source is connected.

Two or more LTC4414s may be interconnected to allow

switchover between multiple batteries or charging of mul-

tiple batteries from a single charger.

The wide supply operating range supports operation from

one to eight Li-Ion cells in series. The low quiescent

current (30µA typical) is independent of the load current.

The gate driver includes an internal voltage clamp for

MOSFET protection.

The STAT pin can be used to enable an auxiliary P-channel

MOSFET power switch when an auxiliary supply is

detected. This pin may also be used to indicate to a micro-

controller that an auxiliary supply is connected. The con-

trol (CTL) input enables the user to force the primary

MOSFET off and the STAT pin low.

The LTC4414 is available in a low profile 8-lead MSOP

package.

LTC4414 vs Schottky Diode Forward Voltage Drop

Downloaded from Arrow.com.

Summary of content (12 pages)

PAGE 1
LTC4414 36V, Low Loss PowerPathTM Controller for Large PFETs DESCRIPTIO U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Designed Specifically to Drive Large QG PFETs Very Low Loss Replacement for Power Supply OR’ing Diodes 3.
PAGE 2
LTC4414 U U W W W Supply Voltage (VIN) .................................. –14V to 40V Voltage from VIN to SENSE ........................ – 40V to 40V Input Voltage CTL ........................................................– 0.3V to 40V SENSE .................................................... –14V to 40V Output Voltage GATE ..................... –0.3V to the Higher of VIN + 0.3V or SENSE + 0.3V STAT .....................................................– 0.
PAGE 3
LTC4414 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, unless otherwise noted specifications are at TA = 25°C, VIN = 12V, CTL and GND = 0V. Current into a pin is positive and current out of a pin is negative. All voltages are referenced to GND, unless otherwise specified. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS –25 190 –7 500 µA µA 8 9 V 0.
PAGE 4
LTC4414 U W TYPICAL PERFOR A CE CHARACTERISTICS VFR vs Temperature and Supply Voltage Normalized Quiescent Supply Current vs Temperature VRTO vs Temperature and Supply Voltage 25 1.05 26 VIN = 3V VIN = 36V 23 CURRENT (µA) VRTO (mV) VFR (mV) VIN = 28V 24 3V ≤ VIN ≤ 36V 1.00 VIN = 36V VIN = 28V VIN = 3V 21 –50 50 0 100 22 –50 150 0 TEMPERATURE (°C) 50 100 VG(OFF) vs Temperature and IGATE 1.0 IGATE = 6µA VIN = 36V VGATE (V) VIN –VGATE (V) 9.
PAGE 5
LTC4414 U U U PI FU CTIO S STAT (Pin 1): Open-Drain Output Status Pin. When the SENSE pin is pulled above the VIN pin with an auxiliary power source by VRTO or more, the reverse turn-off threshold (VRTO) is reached. The STAT pin will then go from an open state to a current sink (IS(SNK)). The STAT pin current sink can be used, along with an external resistor, to turn on an auxiliary P-channel power switch and/or signal the presence of an auxiliary power source to a microcontroller.
PAGE 6
LTC4414 U OPERATIO Operation can best be understood by referring to the Block Diagram, which illustrates the internal circuit blocks along with the few external components, and the graph that accompanies the Typical Application drawing on the front page of the data sheet. The terms primary and auxiliary are arbitrary and may be changed to suit the application. Operation begins when either or both power sources are applied and the CTL control pin is below the input low voltage of 0.35V (VIL).
PAGE 7
LTC4414 U W U U APPLICATIO S I FOR ATIO Introduction The system designer will find the LTC4414 useful in a variety of cost and space sensitive power control applications that include low loss diode OR’ing, fully automatic switchover from a primary to an auxiliary source of power, microcontroller controlled switchover from a primary to an auxiliary source of power, charging of multiple batteries from a single charger and high side power switching.
PAGE 8
LTC4414 U W U U APPLICATIO S I FOR ATIO way to avoid unwanted I • R drops in the power path. Both pins are protected from negative voltages. GATE Pin Usage The GATE pin controls the external P-channel MOSFET connected between the VIN and SENSE pins when the load current is supplied by the power source at VIN. In this mode of operation, the internal current source, which is responsible for pulling the GATE pin up, is limited to a few microamps (IG(SRC)).
PAGE 9
LTC4414 U TYPICAL APPLICATIO S Automatic PowerPath Control The applications shown in Figures 1 and 2 and the typical application shown on the first page of this data sheet are automatic ideal diode controllers that require no assistance from a microcontroller. Each of these will automatically connect the higher supply voltage, after accounting for certain diode forward voltage drops, to the load with application of the higher supply voltage. These circuits are not recommended for load sharing.
PAGE 10
LTC4414 U TYPICAL APPLICATIO S This is due to the SENSE pin voltage rising above the battery voltage and turning off the MOSFET before the Schottky diode turns on. The factors that determine the magnitude of the voltage droop are the auxiliary input rise time, the type of diode used, the value of COUT and the load current. Ideal Diode Control with a Microcontroller Figure 3 illustrates an application circuit for microcontroller monitoring and control of two power sources.
PAGE 11
LTC4414 U TYPICAL APPLICATIO S Battery Load Sharing Figure 5 illustrates an application circuit for dual battery load sharing with automatic switchover of load from batteries to wall adapter. Whichever battery can supply the higher voltage will provide the load current until it is discharged to the voltage of the other battery. The load will then be shared between the two batteries according to the capacity of each battery. The higher capacity battery will provide proportionally higher current to the load.
PAGE 12
LTC4414 U PACKAGE DESCRIPTIO MS8 Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1660) 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 0.889 ± 0.127 (.035 ± .005) 5.23 (.206) MIN 3.20 – 3.45 (.126 – .136) 0.254 (.010) 8 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 4.90 ± 0.152 (.193 ± .006) DETAIL “A” 0.52 (.0205) REF 7 6 5 0° – 6° TYP GAUGE PLANE 0.42 ± 0.038 (.0165 ± .0015) TYP 0.65 (.0256) BSC 0.53 ± 0.152 (.021 ± .006) RECOMMENDED SOLDER PAD LAYOUT DETAIL “A” 1 2 3 4 1.10 (.043) MAX 0.86 (.