Datasheet

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LTC4366-1/LTC4366-2

436612fd

For more information www.linear.com/LTC4366

Typical applicaTion

FeaTures DescripTion

High Voltage Surge Stopper

The LT C

4366 surge stopper protects loads from high

voltage transients. By controlling the gate of an external

N-channel MOSFET, the LTC4366 regulates the output

during an overvoltage transient. The load may remain

operational while the overvoltage is dropped across the

MOSFET. Placing a resistor in the return line isolates the

LTC4366 and allows it to float up with the supply; therefore,

the upper limit on the output voltage depends only on the

availability of high valued resistors and MOSFET ratings.

An adjustable overvoltage timer prevents MOSFET dam

age during the surge while an additional 9 second timer

provides for MOSFET cool down. A shutdown pin reduces

the quiescent current to less than 14µA during shutdown.

After a fault the LTC4366-1 latches off while the L

TC4366-2

will auto-retry.

Overvoltage Protected 1.5A, 28V Supply Overvoltage Protector Regulates Output at 43V During Transient

applicaTions

Rugged Floating Topology

Wide Operating Voltage Range: 9V to >500V

Adjustable Output Clamp Voltage

Controls N-Channel MOSFET

Adjustable Protection Timer

Internal 9 Second Cool-Down Timer

Shutdown I

< 14µA

Available in 8-Lead TSOT and 8-Lead 3mm × 2mm

DFN Packages

Industrial, Automotive and Avionic Surge Protection

High Voltage DC Distribution

28V Vehicle Systems

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

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

Patents pending.

OUT

2nF

GATE

IXTK90N25L2

SD FB

1µF

0.47µF

12.4k

OUT

1.5A

28V

422k

436612 TA01a

46.4k

10Ω

324k

LTC4366-2

TIMER BASEV

28V

100ms/DIV

436612 TA01b

28V

43V CLAMP

250V INPUT SURGE

100V/DIV

OUT

20V/DIV

Summary of content (24 pages)

PAGE 1
LTC4366-1/LTC4366-2 High Voltage Surge Stopper Features n n n n n n n n Description Rugged Floating Topology Wide Operating Voltage Range: 9V to >500V Adjustable Output Clamp Voltage Controls N-Channel MOSFET Adjustable Protection Timer Internal 9 Second Cool-Down Timer Shutdown IQ < 14µA Available in 8-Lead TSOT and 8-Lead 3mm × 2mm DFN Packages Applications n n n Industrial, Automotive and Avionic Surge Protection High Voltage DC Distribution 28V Vehicle Systems The LTC®4366 surge stopper protects lo
PAGE 2
LTC4366-1/LTC4366-2 Absolute Maximum Ratings (Notes 1, 2) All voltages relative to VSS, unless otherwise noted. Supply Voltage (VDD) ................................. –0.3V to 10V Supply Voltage (OUT) .................................. –0.3V to 5V Input Voltages FB............................................... –0.3V to OUT + 0.3V TIMER.................................................... –0.3V to 3.5V SD........................................................... –0.3V to 10V Output Voltages BASE..........
PAGE 3
LTC4366-1/LTC4366-2 Order Information Lead Free Finish TAPE AND REEL (MINI) TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC4366CTS8-1#TRMPBF LTC4366CTS8-1#TRPBF LTFMC 8-Lead Plastic TSOT-23 0°C to 70°C LTC4366ITS8-1#TRMPBF LTC4366ITS8-1#TRPBF LTFMC 8-Lead Plastic TSOT-23 –40°C to 85°C LTC4366HTS8-1#TRMPBF LTC4366HTS8-1#TRPBF LTFMC 8-Lead Plastic TSOT-23 –40°C to 125°C LTC4366CDDB-1#TRMPBF LTC4366CDDB-1#TRPBF LFMD 8-Lead (3mm × 2mm) Plastic DFN 0°C to 70°C LTC43
PAGE 4
LTC4366-1/LTC4366-2 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. All voltages relative to VSS, unless otherwise noted. SYMBOL PARAMETER CONDITIONS VZ(VDD) VDD Shunt Regulator Voltage I = 1mA ∆VZ(VDD) VDD Shunt Regulator Load Regulation I = 1mA to 5mA VDD VDD Supply Voltage (Note 3) MIN TYP MAX UNITS 11.5 12 12.
PAGE 5
LTC4366-1/LTC4366-2 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. All voltages relative to VSS, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS 1.193 1.23 1.267 V FB, SD, TIMER VFB(REG) 3% FB pin Regulation Threshold (OUT-FB) IFB FB Pin Leakage Current OUT-FB = 1.2V l 0 ±1 µA VSD(TH) SD Pin Threshold Voltage (VDD-SD) Falling l 1.0 1.5 2.
PAGE 6
LTC4366-1/LTC4366-2 Typical Performance Characteristics 13.0 VDD Shunt Regulator vs VDD Current VDD Shunt Regulator vs Temperature VDD Start-Up Current vs Temperature (Gate High) 13.0 15 12.5 12 IVDD(STHI) (µA) VZ(VDD) (V) VZ(VDD) (V) 12.5 12.0 12.0 6 11.5 11.5 5 0 10 IVDD (mA) 15 20 9 11.
PAGE 7
LTC4366-1/LTC4366-2 Typical Performance Characteristics Base Shunt Regulator vs Base Current Gate Start-Up Current vs Temperature –12 Timer Pull-Up Current vs Temperature 7.0 –12 –10 ITIMER(UP) (µA) 6.5 VZ(BASE) (V) IGATE(ST) (µA) –10 –8 6.0 –6 –8 –6 –4 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 5.5 125 0 –100 436612 G15 –200 –300 IBASE (µA) –400 –4 –50 –500 100 125 436612 G18 Cool-Down Time vs Temperature 1.
PAGE 8
LTC4366-1/LTC4366-2 Pin Functions BASE: Base Driver Output for External PNP Shunt Regulator. This pin is connected to the anode of an internal 6.2V Zener with the cathode tied to OUT. In cases where lower Zener (Z3) clamp current is desired but a large VSS resistor is prohibited, connect an external PNP base to this pin (PNP collector is grounded, emitter is tied to VSS). Tie this pin to VSS if unused. Exposed Pad: The exposed pad may be left open or connected to VSS.
PAGE 9
LTC4366-1/LTC4366-2 Simplified Diagram Start Run Regulate RIN 7.5µA 1.23V 20µA CP Z1 12V Z3 5.7V + – – + Z3 5.7V RFB1 RFB2 RSS RSS RSS 436612 SD Functional Diagram M1 VIN VOUT RG RIN CG VDD Z4 12V GATE 7.5µA OUT Z1 12V D1 OUT 20µA CHARGE PUMP LOGIC SUPPLY UVLO2 4.75V VCC UVLO1 2.55V VDD VCC 1.6µA + – SHUTDOWN 1.5V COMPARATOR + – SD 1.23V – + LOGIC AND TIMER VCC + – C1 FB RFB1 RFB2 OVERVOLTAGE AMPLIFIER 9µA TIMER COMPARATOR TIMER CT 1.8µA + – + – 2.
PAGE 10
LTC4366-1/LTC4366-2 Operation The Simplified Diagram shows three states of operation: the start, run and regulate mode. Previous surge stopper parts are powered off the input supply, therefore the surge voltage is limited to the breakdown voltage of the input pins of the part. As demonstrated in run and regulate modes, the majority of this part is powered off the output, so the MOSFET isolates the surge from the power pins of the part. This allows surge voltages up to the breakdown of the external MOSFET.
PAGE 11
LTC4366-1/LTC4366-2 Applications Information The typical LTC4366 application is a protected system that distributes power to loads safe from overvoltage transients. External component selection is discussed in the following sections. Dual Shunt Regulators The LTC4366 uses two shunt regulators coupled with the external voltage dropping resistors, RSS and RIN, to generate internal supply rails at the VDD and OUT pins.
PAGE 12
LTC4366-1/LTC4366-2 Applications Information Starting up with a supply voltage insufficient to charge C1 with large load current may result in overheating the MOSFET and subsequent damage. While the gate and output are ramping the drop across the MOSFET is the input supply minus the output. If the supply is lower than necessary to charge C1, then the output fails to ramp higher than the supply minus the threshold of the MOSFET.
PAGE 13
LTC4366-1/LTC4366-2 Applications Information Following an overvoltage fault, putting the part in shutdown will clear the fault, allowing operation to resume once the LTC4366 leaves shutdown. Output Short A sudden short on the output can result in excessive current into the LTC4366 GATE pin supplied from the gate capacitor, CG. The GATE pin is internally clamped to OUT with a 10V to 12V clamp.
PAGE 14
LTC4366-1/LTC4366-2 Applications Information the VDD pin, and finally the current from the VSS pin (see Figure 5.). VIN(MIN) = (IVDD • RIN) + VD + VTH + VC1 + (IVSS • RSS) Using the Electrical Characteristics table for above parameters: The last VIN(MIN) equation sets the maximum value for RSS. After choosing RSS the maximum value for RIN (for that particular RSS) is calculated from the first VIN(MIN) equation: RSS(MAX) = VIN(MIN) – 5.7V 160µA RIN(MAX) = VIN(MIN) – 4.75V – 0.
PAGE 15
LTC4366-1/LTC4366-2 Applications Information has exceeded VREG. Since the OUT pin voltage is at least 2.55V larger than VSS it exceeds the specified maximum. Choosing the match point (with supply at the maximum) sufficiently below VREG (by at least 2.55V), allows C1 to charge up in time to protect the load from overvoltage. In reality having VSS pin voltage 7V below VREG provides required margin for charging C1.
PAGE 16
LTC4366-1/LTC4366-2 Applications Information Layout Considerations DESIGN EXAMPLE Due to the high impedances on the SD, VDD, and GATE pins, these pins are susceptible to leakages to ground. For example, a leakage to ground on SD will activate the shutdown state if greater than 1.6µA. Providing adequate spacing away from grounded traces and adding conformal coating on exposed pins lowers the risk that leakage current will interrupt system operation.
PAGE 17
LTC4366-1/LTC4366-2 Applications Information Table 1. Electrical Parameters Used in Design Example SYMBOL PARAMETER CONDITIONS TYP MAX VZ(OUT) OUT Shunt Reg. Voltage I = 1mA, BASE = 0V 5.7V 6.0V VUVLO2 OUT Undervoltage Lockout 2 Rising 4.75V 4.
PAGE 18
LTC4366-1/LTC4366-2 Applications Information Step 5: Determine CG, C1(MAX), Check RSS The gate capacitor (CG) determines the gate slew rate and therefore the slew rate of the OUT pin since the output voltage follows the GATE pin. The voltage at the GATE pin rises with a slope equal to 7.5µA/CG at startup and 20µA/CG when the charge pump is on.
PAGE 19
LTC4366-1/LTC4366-2 Applications Information times time or P2t. Knowing the power we then adjust the time using the timer capacitor to limit the P2t during overvoltage. In this example the MOSFET data sheet has a 6400W2s P2t for a 10ms single pulse. In order to limit the SD pin current (10mA max) a collector resistor, R1, in series with Q2 is required. The maximum value for this resistor is around 5M. This requirement occurs when the pull-down is required to sink 1.6µA from SD and VDD is clamped at 12V.
PAGE 20
LTC4366-1/LTC4366-2 Applications Information 28V Vehicle Application The circuit in Figure 8 adds reverse voltage protection to the standard 28V application shown in Figure 6. There are three modes to this circuit: pass FET On when the input is 18V to 41V, clamping the output to 43V when more than 43V appears at the input and finally reverse voltage protection when up to –250V DC is present at the input. The reverse voltage protection consists of the circuitry inside the dotted box in Figure 8.
PAGE 21
LTC4366-1/LTC4366-2 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 22
LTC4366-1/LTC4366-2 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. DDB Package 8-Lead Plastic DFN (3mm × 2mm) (Reference LTC DWG # 05-08-1702 Rev B) 0.61 ±0.05 (2 SIDES) 0.70 ±0.05 2.55 ±0.05 1.15 ±0.05 PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC 2.20 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ±0.10 (2 SIDES) R = 0.115 TYP 5 R = 0.05 TYP 0.40 ±0.10 8 2.00 ±0.10 (2 SIDES) PIN 1 BAR TOP MARK (SEE NOTE 6) 0.56 ±0.
PAGE 23
LTC4366-1/LTC4366-2 Revision History REV DATE DESCRIPTION A 1/12 Added Patents Pending statement PAGE NUMBER 1 Revised Figure 4 in Applications Information section 11 B 2/12 Removed reference to overcurrent faults under MOSFET Selection 13 Fixed orientation of M2 in Figure 8 18 C 8/12 Updated Shutdown current from <20µA to <14µA 1 Changed MOSFET part number and Gate Capacitor value used in the Typical Application Added MP-grade order information and specifications Added negative sign to g
PAGE 24
LTC4366-1/LTC4366-2 Typical Application Surge Protected Automotive 12V Supply M1 HUF76639S3S VIN 12V (9V TO 100V) VOUT 4A (18V CLAMP) CG 2nF RG 10Ω RIN 29.4k R1 470k SD R2 100k Q1 MMBT3904 C1 0.47µF VDD GATE SD OUT FB LTC4366-2 TIMER VSS BASE RFB1 12.4k RFB2 169k CT 3.3nF RSS 1.91k 436612 TA02 Related Parts PART NUMBER DESCRIPTION COMMENTS LTC1696 Overvoltage Protection Controller ThinSOT™ Package, 2.