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LINEAR TECHNOLOGY LTC4218 User Manual

Summary

The LTC4218 is a robust Hot Swap controller designed for safely powering components in live backplane environments. This manual provides comprehensive technical details on how the device manages power integrity, offering protection features including adjustable current limiting, undervoltage/overvoltage monitoring, and powergood signaling across wide voltages (2.9V to 26.5V). It is ideal for engineers developing high-reliability server infrastructure, RAID systems, and industrial I/O cards that require dependable power management during module hot-plugging.

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Page 1 Text Content

LTC4218

Hot Swap Controller

FEATURES DESCRIPTION ■ Wide Operating Voltage Range: 2.9V to 26.5V

The LTC®4218 is a Hot Swap™ controller that allows a board

■ Adjustable, 5% Accurate (15m V) Current Limit

to be safely inserted and removed from a live backplane.

■ Current Monitor Output

An internal high side switch driver controls the gate of an

■ Adjustable Current Limit Timer Before Fault

external N-channel MOSFET for supply voltages from 2.9V

■ Powergood and Fault Outputs

to 26.5V. A dedicated 12V version (LTC4218-12) contains

■ Adjustable Inrush Current Control

preset 12V specifi c thresholds, while the standard LTC4218

■ 2% Accurate Undervoltage and Overvoltage

allows adjustable thresholds.

Protection

The LTC4218 provides an accurate (5%) current limit with

■ Available in 16-Lead SSOP and 16-Pin 5mm × 3mm

current foldback limiting. The current limit threshold can

DFN Packages

be adjusted dynamically using an external pin. Additional features include a current monitor output that amplifi es

APPLICATIONS the sense voltage for ground referenced current sensing.

Overvoltage, undervoltage and powergood monitoring

■ RAID Systems

are also provided.

■ ATCA, AMC, μTCA Systems

■ Server I/O Cards , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the

■ Industrial property of their respective owners.

TYPICAL APPLICATION

12V, 6A Card Resident Application Power-Up Waveform

2mΩ Si7108DN VOUT 12V 12V

10V/DIV

10Ω IIN

1A/DIV

SENSE– GATE SOURCE 1k VOUT 10V/DIV

SENSE+

VDD 12V

UV PG LTC4218DHC-12 10k AUTO 10V/DIV

RETRY

4218 TA01b

25ms/DIV

TIMER

0.1μF INTVCC IMON ADC

GND 20k

4218 TA01a

Page Summary Contents For LINEAR TECHNOLOGY LTC4218 User Manual

Page 1 LTC4218 Hot Swap Controller FEATURES DESCRIPTION ■ Wide Operating Voltage Range: 2.9V to 26.5V The LTC®4218 is a Hot Swap™ controller that allows a board ■ Adjustable, 5% Accurate (15m V) Current Limi...
Page 2 LTC4218 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) Supply Voltage (VDD) ................................. –0.3V to 35V INTVCC .................................................. –0.3V to 3.5V Input Voltages...
Page 3 LTC4218 ELECTRICAL CHARACTERISTICS The ● denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VDD = 12V unless otherwise noted...
Page 4 LTC4218 ELECTRICAL CHARACTERISTICS The ● denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VDD = 12V unless otherwise noted...
Page 5 CU RR EN LI IT EN SE OL TA GE UV YS TE RE SI (V (V SE NS E+ SE NS E– ) ( V) (m A) LTC4218 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VDD = 12V unless otherwise noted. UV Low-High Threshold vs IDD ...
Page 6 AT PU LL -U (μ A) GA TE RI VE (V GA TE SO UR CE ) ( V) LTC4218 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VDD = 12V unless otherwise noted. ON (μ A) GATE Pull-Up Current vs Gate Pull-Up Current vs...
Page 7 LTC4218 PIN FUNCTIONS Exposed Pad: Exposed pad may be left open or connected OV: Overvoltage Comparator Input. Connect this pin to to device ground. an external resistive divider from VDD for the LTC4...
Page 8 LTC4218 FUNCTIONAL DIAGRAM SENSE–SENSE+ GATE SOURCE CLAMP CHARGE ISET PUMP AND GATE 20k +– DRIVER 0.6V REFERENCE FOLDBACK 0.6V SOURCE VDD 1.235V UV PG 20k140k UV 1.235V LOGIC VDD 0.2V TM1 INTVCC OV 20...
Page 9 LTC4218 OPERATION The Functional Diagram displays the main circuits of the At this point, the pass transistor has cooled and it is safe device. The LTC4218 is designed to turn a board’s sup- to turn i...
Page 10 LTC4218 APPLICATIONS INFORMATION The typical LTC4218 application is in a high availability The pass transistor is turned on by charging up the GATE system that uses a positive voltage supply to distri...
Page 11 LTC4218 APPLICATIONS INFORMATION its threshold. The PG then pulls low to indicate output Tying the ⎯F ⎯L⎯T pin to the UV pin allows the part to self-clear power is no longer good. the fault and turn t...
Page 12 LTC4218 APPLICATIONS INFORMATION Using a switch (connected to ground) in series with the Powergood Indication external resistor allows the active current limit to change In addition to setting the fol...
Page 13 LTC4218 APPLICATIONS INFORMATION RS Q1 LTC4218-12 VDD 2mΩ Si7108DN RSHUNT2 OV CL RGATE SENSE– GATE SOURCE SENSE+ CGATE RSHUNT1 VDD 12V 4218 F04 LTC4218DHC-12 Figure 4. Adjusting LTC4218-12 Thresholds ...
Page 14 LTC4218 APPLICATIONS INFORMATION After the 1.2ms timeout the ⎯F⎯L⎯T pin needs to pull down In Hot Swap applications where load currents can be 6A, on the UV pin to restart the power-up sequence. narro...
Page 15 LTC4218 PACKAGE DESCRIPTION DHC Package 16-Lead Plastic DFN (5mm × 3mm) (Reference LTC DWG # 05-08-1706) (2 SIDES) 3.00 ±0.10 (2 SIDES) 1.65 ±0.05 1.65 ± 0.10 (2 SIDES) PACKAGE (2 SIDES) 2.20 ±0.05 OU...
Page 16 LTC4218 TYPICAL APPLICATION 24V, 6A Card Resident Application 2mΩ Si7880ADP VOUT 24V 24V 6A SENSE– GATE SOURCE SENSE+ 215k VDD FB UV 10k 4.32k FLT LTC4218GN OV 10k TIMER 0.1μF INTVCC IMON ADC 4218 TA0...

Manual Details

Brand Linear
Pages 16
File Size 197.58 KB
Published June 21, 2026
12 views

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Frequently Asked Questions

What is the primary function of the LTC4218 Hot Swap controller?

It safely allows a board to be inserted and removed from a live backplane.

What is the wide operating voltage range for the standard controller?

The controller supports a wide operating voltage range between 2.9V and 26.5V.

How accurate are the current limit and undervoltage monitoring features?

It provides an adjustable current limit with 5% accuracy, and voltage protection has 2% accuracy.

What types of package options are available for this device?

It is available in 16-Lead SSOP, 16-Lead DFN Packages, and specialized versions like the LTC4218-12.