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LTC4415

4415fa

Typical applicaTion

FeaTures DescripTion

Dual 4A Ideal Diodes with

Adjustable Current Limit

The LTC

4415 contains two monolithic PowerPath ideal

diodes, each capable of supplying up to 4A with typical

forward conduction resistance of 50mΩ. The diode voltage

drops are regulated to 15mV during forward conduction at

low currents, extending the power supply operating range

and ensuring no oscillations during supply switchover.

Less than 1µA of reverse current flows from OUT to IN

making this device well suited for power supply ORing

applications.

The two ideal diodes are independently enabled and

prioritized using inputs EN1 and EN2. The output current

limits can be adjusted independently from 0.5A to 4A

using resistors on the CLIM pins. Furthermore, the ideal

diode currents can be monitored via CLIM pin voltages.

Open-drain status pins indicate when the ideal diodes are

forward conducting. When the die temperature approaches

thermal shutdown, or if the output load exceeds the cur-

rent limit threshold, the corresponding warning pins are

pulled low.

Prioritized Power Supply ORing

applicaTions

Dual 50mΩ Monolithic Ideal Diodes

1.7V to 5.5V Operating Range

Up to 4A Adjustable Current Limit for Each Diode

Low Reverse Leakage Current (1µA Max)

15mV Forward Drop in Regulation

Smooth Switchover in Diode ORing

Load Current Monitor

Precision Enable Thresholds to Set Switchover

Soft-Start to Limit Inrush Current on Start-Up

Status Pins to Indicate Forward Diode Conduction

Current and Thermal Limit with Warning

Thermally Enhanced 16-Lead MSOP and DFN

(3mm × 5mm) Packages

High Current PowerPath™ Switch

Battery and Wall Adapter Diode ORing

Backup Battery Diode ORing

Logic Controlled High Current Power Switch

Supercapacitor ORing

Multiple Battery Sharing

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and

PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the

property of their respective owners.

IDEAL

LTC4415

GND

EN1

4415 TA01a

4.7µF

LOAD

100k

21.5k

124Ω124Ω

CLIM1

CLIM2

STAT1

WARN1

WARN2

STAT2

EN2

IN2

IN1 OUT1

OUT2

PRIMARY

POWER

SOURCE

SECONDARY

POWER

SOURCE

FORWARD VOLTAGE DROP (mV)

LOAD CURRENT (A)

400

4415 TA01b

100

200

300

500

CURRENT LIMIT

LTC4415

= 50mΩ

SCHOTTKY

DIODE

MBRS410E

Forward Characteristics of LTC4415

vs MBRS410E Schottky

Summary of content (20 pages)

PAGE 1
LTC4415 Dual 4A Ideal Diodes with Adjustable Current Limit Features n n n n n n n n n n n n Description Dual 50mΩ Monolithic Ideal Diodes 1.7V to 5.
PAGE 2
LTC4415 Absolute Maximum Ratings (Note 1) IN1, IN2, OUT1, OUT2, CLIM1, CLIM2, STAT1, STAT2, WARN1, WARN2 Voltage........ –0.3V to 6V EN1, EN2 Voltage.................. –0.3V to Max (VINx, VOUTx) Operating Junction Temperature Range (Notes 3, 4)..............................................–40°C to 125°C Storage Temperature Range................... –65°C to 150°C Peak Reflow Temperature......................................
PAGE 3
LTC4415 Electrical Characteristics The l denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25°C (Notes 2, 3). VIN1 = VIN2 = 3.6V, RCLIM = 250Ω, unless otherwise specified. SYMBOL PARAMETER VIN1, VOUT1, Operating Supply Range VIN2, VOUT2 CONDITIONS MIN At Least One Input/Output Must Be in This Range l TYP 1.7 MAX UNITS 5.5 V VUVLO Undervoltage Lockout VINx Rising Hysteresis l 1.63 55 1.
PAGE 4
LTC4415 Electrical Characteristics The l denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25°C (Notes 2, 3). VIN1 = VIN2 = 3.6V, RCLIM = 250Ω, unless otherwise specified.
PAGE 5
LTC4415 Typical Performance Characteristics TA = 25°C, VIN1 = VIN2 = 3.6V, RCLIM = 250Ω unless otherwise noted. Reverse Leakage Current vs Temperature Quiescent Current vs Temperature 100 ILEAK(IN) (A) 100n QUIESCENT CURRENT (µA) 1µ VOUT = 5.5V 10n VOUT = 3.
PAGE 6
LTC4415 Typical Performance Characteristics TA = 25°C, VIN1 = VIN2 = 3.6V, RCLIM = 250Ω unless otherwise noted. Enable and Disable Response for Large Load Capacitor VOUT1 2V/DIV Enable and Disable Response for Small Load Capacitor VOUT1 2V/DIV COUT1 = 1200µF RLOAD1 = 8Ω 1ms/DIV 4415 G12 VOUT1,2 1V/DIV COUT1 = 47µF RLOAD1 = 8Ω Load Step Response 1ms/DIV 4415 G13 STAT1 5V/DIV STAT2 5V/DIV 3.6V VIN 5V/DIV 3.6V VIN 5V/DIV VOUT 5V/DIV 3.6V 10mA 4415 G14 COUT = 4.
PAGE 7
LTC4415 Typical Performance Characteristics TA = 25°C, VIN1 = VIN2 = 3.6V, RCLIM = 250Ω unless otherwise noted. Power Loss vs Output Current 1.0 Efficiency vs Output Current 100 RCLIM = 124Ω 98 EFFICIENCY (%) POWER LOSS (W) 0.8 0.6 0.4 0.2 0 RCLIM = 124Ω 99 2 1 3 OUTPUT CURRENT (A) 96 95 94 93 92 125°C 25°C –40°C 0 97 125°C 25°C –40°C 91 4 4415 G21 90 0 2 1 3 OUTPUT CURRENT (A) 4 4415 G22 Pin Functions IN1 (Pins 1, 2): Diode 1 Anode and Positive Power Supply for LTC4415.
PAGE 8
LTC4415 Pin Functions STAT1 (Pin 14): Status Indicator for Diode 1. Open-drain output pulls down during forward diode conduction. This pin can be left open or grounded when not used. OUT1 (Pins 15, 16): Diode 1 Cathode and Output of LTC4415. Bypass OUT1 with a ceramic capacitor of at least 4.7µF. Pins 15 and 16 are fused together on the package. Leave these pins open when not used. GND (Exposed Pad Pin 17): Device Ground.
PAGE 9
LTC4415 Operation The diodes are enabled using level-sensitive enable inputs EN1 and EN2 with opposite polarity to achieve a prioritizer function with minimal quiescent current during diode-OR implementation. The enable threshold on the enable pins (VENTH) is 800mV (typical) with one-sided hysteresis of 55mV (typical). For rising voltage on the EN1 pin, Diode 1 is enabled when VEN1 > 800mV (typical), and on the falling edge it is disabled when VEN1 < 745mV (typical).
PAGE 10
LTC4415 Operation when the load current decreases below the current limit. Power consumption in LTC4415 increases during operation in current limit due to the large voltage drop across the PFET devices (P1 or P2). Load Current Monitor The current limit pins output 1/1000th of the ideal diode output current.
PAGE 11
LTC4415 Operation Undervoltage Lockout Each ideal diode contains an independent UVLO control circuit so that one input experiencing undervoltage lockout does not hinder normal operation of the other channel. The diode conduction path is turned off and the status signal, STAT1/STAT2, is deasserted during an undervoltage condition. Applications Information Stability Considerations Any capacitance on the CLIM pins adds a pole to the current control loop.
PAGE 12
LTC4415 Applications Information Board Layout Considerations When laying out the printed circuit board, the following checklist should be followed to ensure proper operation of the LTC4415: 1. Connect the exposed pad of the package (Pin 17) directly to a large PC board ground to minimize thermal impedance. Correctly soldered to a 2500mm2 double-sided 1oz copper board, the DFN package has a thermal resistance (θJA) of approximately 43°C/W.
PAGE 13
LTC4415 Typical Applications Precision enable inputs and independent status outputs provide flexibility in power supply back up and load share applications using the two high current ideal diode circuits in the LTC4415, as shown in the following examples. The features shown in these application circuits can be combined in custom applications as needed. The enable overlap minimizes the load voltage droop during switchover. Both input power supplies provide power to the load during the overlap.
PAGE 14
LTC4415 Typical Applications non-critical high current loads. If the status resistors are pulled up through the keep-alive power source itself as shown in Figure 6, the output voltage is limited to: Multiple Battery Charging Figure 7 illustrates an application circuit for automatic dual battery charging from a single charger. The battery with lower voltage receives larger charging current until both battery voltages are equal, then both are charged.
PAGE 15
LTC4415 Typical Applications Load Sharing by Multiple Batteries and Automatic Switchover to a Preferred Power Supply (Such as a Wall Adapter) Microcontrolled Power Switch with Reverse Blocking, Selectable Current Limit, Soft-Start and Monitoring An application circuit for dual battery load sharing with automatic switchover to a wall adapter (when present) is shown in Figure 8.
PAGE 16
LTC4415 Typical Applications PRIMARY POWER SOURCE IDEAL IN1 OUT1 LTC4415 EN1 CLIM1 CLIM2 MICROCONTROLLER LOAD 470k STAT1 WARN1 WARN2 STAT2 MN1 IRLML2402 EN2 AUXILLIARY POWER SOURCE IN2 IDEAL OUT2 4.7µF GND 4415 F09 Figure 9. Microcontrolled PowerPath Monitoring and Control POWER SOURCE IDEAL IN1 OUT1 LTC4415 EN1 CLIM1 CLIM2 ENABLE EN2 IN2 LOAD 470k STAT1 WARN1 WARN2 STAT2 IDEAL OUT2 4415 F10 GND D1 1N5817 Figure 10.
PAGE 17
LTC4415 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. DHC Package 16-Lead Plastic DFN (5mm × 3mm) (Reference LTC DWG # 05-08-1872 Rev Ø) Variation A 0.65 ±0.05 1.29 ±0.05 3.50 ±0.05 1.65 ±0.05 2.20 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 4.40 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 5.00 ±0.10 (2 SIDES) R = 0.20 TYP 9 R = 0.115 TYP 0.40 ±0.10 16 1.29 REF 3.00 ±0.10 (2 SIDES) 1.65 ±0.
PAGE 18
LTC4415 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. MSE Package 16-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1667 Rev E) BOTTOM VIEW OF EXPOSED PAD OPTION 2.845 ±0.102 (.112 ±.004) 5.23 (.206) MIN 2.845 ±0.102 (.112 ±.004) 0.889 ±0.127 (.035 ±.005) 8 1 1.651 ±0.102 (.065 ±.004) 1.651 ±0.102 3.20 – 3.45 (.065 ±.004) (.126 – .136) 0.305 ±0.038 (.0120 ±.0015) TYP 16 0.50 (.0197) BSC 4.039 ±0.102 (.159 ±.
PAGE 19
LTC4415 Revision History REV DATE DESCRIPTION A 4/12 Clarified footnotes and added new Note 5 for quiescent current PAGE NUMBER 3, 4 Changed FET MP1 part number on Figure 8 15 4415fa 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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
PAGE 20
LTC4415 Typical Application Power Backup Using Supercapacitors and Optional Keep-Alive Cell KEEP-ALIVE/COIN CELL M1 M2 VDD VOUT VIN 294k 100k EN PFI CTL LTC3625 VSEL GND SW1 L1 3.3µH L2 3.3µH SW2 VMID PROG IDEAL IN1 GND PFO RPROG 78.7k CTOP 360F 300k CBOT 360F 200k DMN2215UDM OUT1 47µF LTC4415 EN1 125Ω STAT1 WARN1 WARN2 STAT2 CLIM1 CLIM2 47k 22µF EN2 IDEAL GND BURST 4.7µH 137k 68.1k LTC3521 PWM VOUT2 1.8V 10µF 0.6A FB2 VOUT1 1.