LTC4352CMS-PBF データシートの表示（PDF） - Linear Technology

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LTC4352CMS-PBF

Low Voltage Ideal Diode Controller with Monitoring

Linear Technology 

LTC4352

APPLICATIONS INFORMATION

Undervoltage and Overvoltage Protection

Unlike a regular diode, the LTC4352 can prevent out of

range input voltages from affecting the load voltage. This

requires back-to-back MOSFETs, and resistive dividers

from the input to the UV and OV pins. For an example,

see Figure 5.

MOSFET Q2 is required to block conduction through the

body diode of Q1 when its gate is held off. The resistive

dividers set up the input voltage range where the ideal

diode control is allowed to operate. Outside this range,

the gate is held off and the FAULT pin pulls low.

When using a CPO capacitor in circuit with back-to-back

MOSFETs, there will be a large inrush current to the

load capacitance due to the fast gate turn-on after UV,

OV levels are met. Without the capacitor, the inrush will

depend on the CPO pull-up current charging up the gate

capacitance.

Q2

Q1

Si7336ADP Si7336ADP

5V

TO LOAD

0.15μF

31.6k

1%

1k

1%

3.09k

1%

C2

R3 VIN CPO SOURCE GATE OUT

UV

FAULT

R2

OV

LTC4352

STATUS

VCC

R1

REV

GND

4352 F05

C1

0.1 μF

Figure 5. 5V Ideal Diode with UV and OV Protection

Inrush Control

The LTC4352 can be used for inrush control in applications

where the input supply is hot-plugged. See Figure 6. The

CPO capacitor is omitted, since fast turn-on with stored

charge is not desired here. Undervoltage holds the gate

off till the short pin makes contact. 40μs after the UV level

is satisfied, the MOSFET gate ramps up due to the CPO

pull-up current. A RC network on the gate further slows

down the output dV/dt, while allowing fast turn-off during

reverse current or overvoltage conditions. Resistor RG

prevents high frequency oscillations in Q2. A dedicated

hot swap controller may be needed if overcurrent protec-

tion is also desired.

12V

Z1

105k

5.11k

R3 VIN

UV

R2

OV

GND

BACKPLANE CONNECTORS

Q2

Si7336ADP

Q1

Si7336ADP

TO LOAD

R6

10k

RG

10Ω

CG

0.1μF

SOURCE GATE OUT

LTC4352

CPO

N/C

GND

4352 F06

Z1: DIODES INC. SMAJ12A

PLUG-IN CARD

Figure 6. Inrush and Ideal Diode Control on a Hot Swap Card

4352f

10

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