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LTC4360-1/LTC4360-2

436012fa

TYPICAL APPLICATION

DESCRIPTION

Overvoltage Protection

Controller

The LTC

4360 overvoltage protection controller safeguards

2.5V to 5.5V systems from power supply overvoltage. It is

designed for portable devices with multiple power supply

options including wall adaptors, car battery adaptors and

USB ports.

The LTC4360 controls an external N-channel MOSFET in

series with the input power supply. During overvoltage

transients, the LTC4360 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 LTC4360

provides protection from transients up to 80V without

requiring transient voltage suppressors or other external

components.

The LTC4360 has a delayed start-up and an adjustable dV/dt

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

power good monitoring for V

. Following an overvolt-

age condition, the LTC4360 automatically restarts with a

start-up delay. The LTC4360-1 features a soft shutdown

controlled by the ON pin, while the LTC4360-2 controls an

optional external P-channel MOSFET for negative voltage

protection.

Output Protected from Overvoltage at Input

FEATURES

APPLICATIONS

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

<1µs Overvoltage Turn-Off, Gentle Shutdown

Controls N-Channel MOSFET

Adjustable Power-Up dV/dt Limits Inrush

Reverse Voltage Protection (LTC4360-2)

Power Good Output

Low Current Shutdown (LTC4360-1)

Available in a Tiny 8-Lead SC70 Package

USB Protection

Handheld Computers

Cell/Smart Phones

MP3/MP4 Players

Digital Cameras

GATE

Si1470DH

436012 TA01a

OUT

1.5A

LTC4360-1

OUT

PWRGD

GND

OUT

Protection from Overvoltage

GATE

10V/DIV

, V

OUT

5V/DIV

0.5µs/DIV

436012 TA01b

Si1470DH

OUT

= 10µF

OUT

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

ThinSOT, PowerPath, How Swap and No R

SENSE

are trademarks of Linear Technology

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

Summary of content (14 pages)

PAGE 1
LTC4360-1/LTC4360-2 Overvoltage Protection Controller FEATURES 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
LTC4360-1/LTC4360-2 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) Bias Supply Voltage (IN)............................. –0.3V to 85V Input Voltages OUT, ON.................................................... –0.3V to 9V Output Voltages PWRGD..................................................... –0.3V to 9V GATE (Note 3)......................................... –0.3V to 15V GATEP..................................................... –0.3V to 85V IN to GATEP............................................ –0.
PAGE 3
LTC4360-1/LTC4360-2 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 (LTC4360-1) unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Supplies VIN Input Voltage Range VIN(UVL) Input Undervoltage Lockout IIN Input Supply Current l 2.5 80 V VIN Rising l 1.8 2.1 2.45 V LTC4360-1 VON = 0V, LTC4360-2 l 220 400 µA LTC4360-1 VON = 2.5V l 1.
PAGE 4
LTC4360-1/LTC4360-2 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = 5V, VON = 0V (LTC4360-1) unless otherwise noted. Input Supply Current vs Input Voltage 1000 40 8 LTC4360-1 VON = 0V, LTC4360-2) 7 6 10 ∆VGATE (V) VON = 2.5V (LTC4360-1) 1 5 VIN = 3V 4 VIN = 2.5V 3 VIN = 6V VGATE = 9V 35 VIN = 5V IGATE(FST) (mA) 100 IIN (µA) GATE Fast Pull-Down Current vs Temperature GATE Drive vs GATE Current 30 25 2 1 0.
PAGE 5
LTC4360-1/LTC4360-2 PIN FUNCTIONS 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. An internal GATE high comparator controls the PWRGD pin.
PAGE 6
LTC4360-1/LTC4360-2 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. The sensitive electronics are susceptible to damage from transient or DC overvoltage conditions from the power supply. Failures or faults in the power adaptor can cause an overvoltage event.
PAGE 7
LTC4360-1/LTC4360-2 APPLICATIONS INFORMATION The GATE ramp rate is limited to 3V/ms. VOUT follows at a similar rate which results in an inrush current into the load capacitor COUT of: IINRUSH = COUT An even slower GATE ramp and lower inrush current can be achieved by connecting an external capacitor, CG, from GATE to ground. The voltage at GATE then ramps up with a slope equal to 10µA/CG [V/s].
PAGE 8
LTC4360-1/LTC4360-2 APPLICATIONS INFORMATION MOSFET Configurations and Selection The LTC4360 can be used with various external MOSFET configurations (see Figure 3). The simplest configuration is a single N-channel MOSFET. It has the lowest RDS(ON) and voltage drop and is thus the most power efficient solution. When GATE is pulled to ground, the MOSFET can isolate OUT from a positive voltage at IN up to the BVDSS of the MOSFET.
PAGE 9
LTC4360-1/LTC4360-2 APPLICATIONS INFORMATION LIN and RIN form an LC tank circuit with any capacitance at IN. If the wall adaptor is powered up first, plugging the wall adaptor output to IN does the equivalent of applying a voltage step to this LC circuit. The resultant voltage overshoot at IN can rise to twice the DC out- WALL ADAPTOR AC/DC LIN RIN MOBILE DEVICE IN ICABLE VIN 10V/DIV COUT + put voltage of the wall adaptor as shown in Figure 4.
PAGE 10
LTC4360-1/LTC4360-2 APPLICATIONS INFORMATION As the IN pin can withstand up to 80V, a high voltage Nchannel 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 LTC4360 controlling a 60V rated MOSFET. Input transients also occur when the current through the cable inductance changes abruptly. This can happen when the LTC4360 turns off the N-channel MOSFET rapidly in an overvoltage event.
PAGE 11
LTC4360-1/LTC4360-2 APPLICATIONS INFORMATION 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 LTC4360 limits this to a 1V rise in the output voltage.
PAGE 12
LTC4360-1/LTC4360-2 PACKAGE DESCRIPTION SC8 Package 8-Lead Plastic SC70 (Reference LTC DWG # 05-08-1639 Rev Ø) 0.30 MAX 0.50 REF PIN 8 1.80 – 2.20 (NOTE 4) 1.00 REF INDEX AREA (NOTE 6) 1.80 – 2.40 1.15 – 1.35 (NOTE 4) 2.8 BSC 1.8 REF PIN 1 RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.10 – 0.40 0.50 BSC 0.15 – 0.27 8 PLCS (NOTE 3) 0.80 – 1.00 1.00 MAX 0.00 – 0.10 REF GAUGE PLANE 0.15 BSC 0.26 – 0.46 0.10 – 0.18 (NOTE 3) SC8 SC70 0905 REV Ø NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2.
PAGE 13
LTC4360-1/LTC4360-2 REVISION HISTORY REV DATE DESCRIPTION PAGE NUMBER A 01/11 Revised Features 1 Revised conditions for VGATEP(CLP) and tOFF in Electrical Characteristics section 3 Revised GATE Control in Applications Information section 6 436012fa Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use.
PAGE 14
LTC4360-1/LTC4360-2 TYPICAL APPLICATION 5V System Protected from ±24V Power Supplies 5V System Protected from ±24V Power Supplies and Reverse Current Si3590DV M2 VIN 5V M1 COUT 10µF VIN 5V VOUT 5V 0.5A FDC6561AN M2 Si1471DH M1 COUT 10µF VIO 5V OUT IN IN R1 1k LTC4360-2 VIO 5V OUT R1 1k LTC4360-2 D1 LN1351CTR PWRGD GND VOUT 5V 0.