IR3086AMPBF 查看數據表（PDF） - International Rectifier

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IR3086AMPBF

XPHASE™ PHASE IC WITH OVP, FAULT AND OVERTEMP DETECT

International Rectifier 

IR3086APbF

IR3086APbF THEORY OF OPERATION

Block Diagram

The Block diagram of the IR3086APbF is shown in Fig. 6, and specific features are discussed in the following

sections.

RMPIN+

RMPIN-

EAIN

BIASIN

PWMRMP

SCOMP

ISHARE

LGND

VRHOT

HOTSET

RAMP

COMPARATOR

CLOCK

PULSE

GENERATOR

PWM

COMPARATOR

-

SYSTEM

BIRAESFIENRENCE

VOLTAGE

+

ENABLE

PWM

LATCH

S

RESET

DOMINANT

R

ENABLE

RAMP

SLOPE VDAC

ADJUST

RAMP

DISCHARGE

CLAMP

BODY BRAKING

COMPARATOR

-

+

GATE

2V

NON-OVERLAP

COMPARATORS

SHARE

ADJUST

SCOMEPRROR

AMP

X

0.91

+

10K

20mV

-

VRHOT

COMPARATOR

+

VDAC +

VDAC

+ VOLTAGE

PROPORTIONAL

TO ABSOLUTE

- TEMPERATURE

CURRENT

SENSE

AMP

X34

-

+

OVP

COMPARATOR

+

125mV

-

INTERNAL

CIRCUVICTC

BIAS

FAULT

COMPARATOR

VCCH

GATEH

VCCL

GATEL

PGND

VCC

DACIN

CSIN+

CSIN-

PHSFLT

Figure 6 – IR3086APbF Block Diagram

Tri-State Gate Drivers

The gate drivers can deliver up to 3A peak current. An adaptive non-overlap circuit monitors the voltage on the

GATEH and GATEL pins to prevent MOSFET shoot-through current while minimizing body diode conduction.

An Enable signal is provided by the Control IC to the Phase IC without the addition of a dedicated signal line. The

Error Amplifier output of the Control IC drives low in response to any fault condition such as input under voltage or

output overload. The IR3086APbF Body BrakingTM comparator detects this and drives both gate outputs low. This

tri-state operation prevents negative inductor current and negative output voltage during power-down.

The Gate Drivers revert to a high impedance “off” state if VCCL and VCCH supply voltages are below the normal

operating range. An 80kΩ resistor is connected across the GATEH/GATEL and PGND pins to prevent the

GATEH/GATEL voltage from rising due to leakage or other causes under these conditions.

Over Voltage Protection (OVP)

The IR3086APbF includes over-voltage protection that turns on the low side MOSFET to protect the load in the

event of a shorted high-side MOSFET or connection of the converter output to an excessive output voltage. A

comparator monitors the voltage at the CSIN- pin which is usually connected directly to the converter output. If the

voltage exceeds the DACIN voltage plus 125mV typical (100mV minimum and 160mV maximum) the GATEL pin

drives high. The OVP circuit overrides the normal PWM operation and will fully turn-on the low side MOSFET within

approximately 150ns. The low side MOSFET will remain ON until the over-voltage condition ceases.

Page 11 of 33

1/28/2005

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