Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - power management - special purpose 220 µA TSOT 23 8

LTC4361-1/LTC4361-2

436112fb

Typical applicaTion

DescripTion

Overvoltage/Overcurrent

Protection Controller

applicaTions

USB Protection

Handheld Computers

Cell/Smart Phones

MP3/MP4 Players

Digital Cameras

2.5V to 5.5V Operation

Overvoltage Protection Up to 80V

No Input Capacitor or TVS Required for Most

Applications

2% Accurate 5.8V Overvoltage Threshold

10% Accurate 50mV Overcurrent Circuit Breaker

<1µs Overvoltage Turn-Off, Gentle Shutdown

Controls N-Channel MOSFET

Adjustable Power-Up dV/dt Limits Inrush Current

Reverse Voltage Protection

Power Good Output

Low Current Shutdown

Latchoff (LTC4361-1) or Auto-Retry (LTC4361-2)

After Overcurrent

Available in 8-Lead ThinSOT™ and 8-Lead

(2mm × 2mm) DFN Packages

The LT C

4361

overvoltage/overcurrent protection control-

ler safeguards 2.5V to 5.5V systems from input supply

overvoltage. It is designed for portable devices with

multiple power supply options including wall adaptors,

car battery adaptors and USB ports.

The LTC4361 controls an external N-channel MOSFET in

series with the input power supply. During overvoltage

transients, the LTC4361 turns off the MOSFET within

1µs, isolating downstream components from the input

supply. Inductive cable transients are absorbed by the

MOSFET and load capacitance. In most applications, the

LTC4361 provides protection from transients up to 80V

without requiring transient voltage suppressors or other

external components.

The LTC4361 has a delayed start-up and adjustable dV/dt

ramp-up for inrush current limiting. A PWRGD pin provides

power good monitoring for V

. The LTC4361 features a soft

shutdown controlled by the ON pin and drives an optional

external P-channel MOSFET for negative voltage protection.

Following an overvoltage condition, the LTC4361 automati-

cally restarts with a start-up delay. After an overcurrent

fault, the LTC4361-1 remains off while the LTC4361-2

automatically restarts after a 130ms start-up delay.

L, LT , LT C , LT M, Linear Technology and the Linear logo are registered trademarks and

ThinSOT, Hot Swap, No R

SENSE

and PowerPath are trademarks of Linear Technology

Corporation. All other trademarks are the property of their respective owners.

Output Protected from Overvoltage at Input

Protection from Overvoltage and Overcurrent

GATE

Si1470DH

0.025Ω

SENSE

436112 TA01a

OUT

1.5A

LTC4361

OUT

PWRGD

GND

OUT

GATE

10V/DIV

, V

OUT

5V/DIV

0.5µs/DIV

436112 TA01b

Si1470DH

OUT

= 10µF

OUT

FeaTures

Summary of content (16 pages)

PAGE 1
LTC4361-1/LTC4361-2 Overvoltage/Overcurrent Protection Controller Features n n n n n n n n n n n n n Description 2.5V to 5.5V Operation Overvoltage Protection Up to 80V No Input Capacitor or TVS Required for Most Applications 2% Accurate 5.
PAGE 2
LTC4361-1/LTC4361-2 Absolute Maximum Ratings (Notes 1, 2) Bias Supply Voltage (IN)............................. –0.3V to 85V Input Voltages SENSE.................................................... –0.3V to 85V OUT, ON.................................................... –0.3V to 9V Output Voltages PWRGD..................................................... –0.3V to 9V GATE (Note 3)......................................... –0.3V to 15V GATEP..................................................... –0.
PAGE 3
LTC4361-1/LTC4361-2 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 5V, VON = 0V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS 80 V 2.1 2.47 V Supplies VIN Input Voltage Range l 2.5 VIN(UVL) Input Undervoltage Lockout VIN Rising l 1.8 IIN Input Supply Current VON = 0V l 220 400 µA VON = 2.5V l 1.
PAGE 4
LTC4361-1/LTC4361-2 Typical Performance Characteristics TA = 25°C, VIN = 5V, VON = 0V, unless otherwise noted. Input Supply Current vs Input Voltage GATE Fast Pull-Down Current vs Temperature GATE Drive vs GATE Current 40 8 10000 7 6 100 ∆VGATE (V) IIN (µA) VON = 0V VON = 2.5V 10 5 VIN = 3V 4 3 VIN = 2.5V 2 1 35 VIN = 5V IGATE(FST) (mA) 1000 VIN = 6V VGATE = 9V 30 25 1 0.
PAGE 5
LTC4361-1/LTC4361-2 Pin Functions Exposed Pad (DFN): Ground. Connection to PCB is optional. GATE: Gate Drive for External N-Channel MOSFET. An internal charge pump provides a 10µA pull-up current to charge the gate of the external N-channel MOSFET. An additional ramp circuit limits the GATE ramp rate when turning on to 3V/ms. For slower ramp rates, connect an external capacitor from GATE to GND. An internal clamp limits GATE to 6V above the OUT pin voltage.
PAGE 6
LTC4361-1/LTC4361-2 Block Diagram GATEP IN CHARGE PUMP 1.8M 10µA GATE HIGH COMPARATOR + – 5µA OVERCURRENT COMPARATOR + – – CONTROL OUT VGATE(TH) + + 1V GATE 5.8V OVERVOLTAGE COMPARATOR 50mV – ON SENSE 5.8V 200k 500k + – 5.8V 5.7V PWRGD GND 436112 BD Operation Mobile devices like cell phones and MP3/MP4 players have highly integrated subsystems fabricated from deep submicron CMOS processes. The small form factor is accompanied by low absolute maximum voltage ratings.
PAGE 7
LTC4361-1/LTC4361-2 Applications Information The typical LTC4361 application protects 2.5V to 5.5V systems in portable devices from power supply overvoltage. The basic application circuit is shown in Figure 1. Device operation and external component selection is discussed in detail in the following sections. VIN 5V M1 Si1470DH RSENSE 0.025Ω COUT 10µF VOUT 5V 1.5A GATE SENSE OUT LTC4361 IN ON PWRGD GND 436112 F01 Figure 1.
PAGE 8
LTC4361-1/LTC4361-2 APPLICATIONS INFORMATION The LTC4361-1 has an internal latch that maintains this off state until it is reset. To reset this latch, cycle IN below 2.1V (VIN(UVL)) or ON above 1.5V (VON(TH)) for more than 500µs. After reset, the LTC4361-1 goes through the start-up cycle. In applications not requiring the overcurrent protection, tie the SENSE pin to the IN pin.
PAGE 9
LTC4361-1/LTC4361-2 Applications Information ON Input ON is a CMOS compatible, active low enable input. It has a default 5µA pull-down to ground. Connect this pin to ground or leave open to enable normal device operation. If it is driven high while the external MOSFET is turned on, GATE is pulled low with a weak pull-down current (40µA) to turn off the external MOSFET gradually, minimizing input voltage transients. The LTC4361 then goes into a low current sleep mode, drawing only 1.5µA at IN.
PAGE 10
LTC4361-1/LTC4361-2 Applications Information WALL ADAPTOR AC/DC RIN LIN MOBILE DEVICE IN ICABLE VIN 10V/DIV COUT + CABLE LOAD ICABLE 20A/DIV 436112 F04a 5µs/DIV RIN = 150mΩ, LIN = 0.7µH LOAD = 10Ω, COUT = 10µF 436112 F04b 5µs/DIV RIN = 150mΩ, LIN = 0.7µH, RSENSE = 25mΩ LOAD = 10Ω, COUT = 10µF 436112 F05b Figure 4.
PAGE 11
LTC4361-1/LTC4361-2 Applications Information As the IN pin can withstand up to 80V, a high voltage N-channel MOSFET can be used to protect the system against rugged abuse from high transient or DC voltages up to the BVDSS of the MOSFET. Figure 6 shows a 50V input plugged into the LTC4361 controlling a 60V rated MOSFET. Input transients also occur when the current through the cable inductance changes abruptly.
PAGE 12
LTC4361-1/LTC4361-2 Applications Information Figure 8 shows a particularly severe situation which can occur in a mobile device with dual power inputs. A 20V wall adaptor is mistakenly hot-plugged into the 5V device with the USB input already live. As shown in Figure 9, a large current can build up in LIN to charge up COUT . When the N-channel MOSFET shuts off, the energy stored in LIN is dumped into COUT, causing a large 40V input transient. The LTC4361 limits this to a 1V rise in the output voltage.
PAGE 13
LTC4361-1/LTC4361-2 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. DC8 Package 8-Lead Plastic DFN (2mm × 2mm) (Reference LTC DWG # 05-08-1719 Rev A) 0.70 ±0.05 2.55 ±0.05 1.15 ±0.05 0.64 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ±0.05 0.45 BSC 1.37 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED R = 0.05 TYP 2.00 ±0.10 (4 SIDES) PIN 1 BAR TOP MARK (SEE NOTE 6) R = 0.
PAGE 14
LTC4361-1/LTC4361-2 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. TS8 Package 8-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1637 Rev A) 0.40 MAX 2.90 BSC (NOTE 4) 0.65 REF 1.22 REF 1.4 MIN 3.85 MAX 2.62 REF 2.80 BSC 1.50 – 1.75 (NOTE 4) PIN ONE ID RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.22 – 0.36 8 PLCS (NOTE 3) 0.65 BSC 0.80 – 0.90 0.20 BSC 0.01 – 0.10 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 0.09 – 0.
PAGE 15
LTC4361-1/LTC4361-2 Revision History REV DATE DESCRIPTION PAGE NUMBER A 01/11 Revised conditions for VGATE(CLP) and tOFF in Electrical Characteristics section 3 Revised GATE Control in Applications Information section 7 B 05/12 Added H-grade order information 2 Change to Electrical Characteristics Input Undervoltage Lockout 3 Added VIN(OVL) specifications 3 Change to Electrical Characteristics Overvoltage Hysteresis 3 Change to Electrical Characteristics GATE Pull-Up and Pull-Down Curren
PAGE 16
LTC4361-1/LTC4361-2 Typical Application 5V System Protected from ±24V Power Supplies and Overcurrent VIN 5V M2 Si3590DV RSENSE 0.05Ω M1 COUT 10µF VOUT 5V 0.5A 5V System Protected from ±24V Power Supplies, Overcurrent and Reverse Current VIN 5V M2 Si1471DH FDC6561AN RSENSE 0.05Ω M1 M3 COUT 10µF GATE VOUT 5V 0.