IR1152S View Datasheet(PDF) - International Rectifier

Part Name

Description

Manufacturer

IR1152S

FIXED 66kHz FREQUENCY, µPFC ONE CYCLE CONTROL PFC IC WITH BROWN-OUT PROTECTION

International Rectifier 

IR1152S

IR1152 Pin Description

Pin COM: This is ground potential pin of the IC.

All internal devices are referenced to this point.

Pin COMP: External circuitry from this pin to

ground compensates the system voltage loop and

programs the soft start time. The COMP pin is

essentially the output of the voltage error amplifier.

The voltage loop error signal Vm used in the control

algorithm is derived from VCOMP (Vm =VCOMP–

VCOMP,START). VCOMP is actively discharged using an

internal resistance to below VCOMP,START threshold

whenever the IC is pushed into Stand-by mode

(BOP or OLP condition) or UVLO/Sleep mode. The

gate drive output and logic functions of the IC are

inactive if VCOMP is less than VCOMP,START. Also

during start-up, the VCOMP voltage has to be less

than VCOMP,START in order to commence operation

(i.e. a pre-bias on VCOMP will not allow IC to

commence operation).

Pin ISNS: ISNS pin is tied to the input of the

current sense amplifier of the IC. The voltage at

this pin, which provides the current sense

information to the IC, has to be a negative voltage

wrt the COM pin. Also since the IC is based on

average current mode, the entire inductor current

information is necessary. A current sense resistor,

located below system ground along the return path

to the bridge rectifier, is the preferred current

sensing method. ISNS pin is also the inverting input

to the cycle-by-cycle peak current limit comparator.

Whenever VISNS exceeds VISNS(PK) threshold in

magnitude, the gate drive is instantaneously

disabled. Any external filtering of the ISNS pin must

be performed carefully in order to ensure that the

integrity of the current sense signal is maintained

for cycle-by-cycle peak current limit protection.

Pin BOP (Brown-out Protection): This pin is used

to sense the rectified AC input line voltage through

a resistor divider/capacitor network which is in

effect a voltage division and averaging network,

representing a scaled down signal of the average

rectified input voltage (average DC voltage + 2xfAC

ripple). During start-up the BOP pin voltage has to

exceed VBOP(EN) in order to enable the IC to exit

Stand-by mode and enter normal operation. A

Brown-out situation is detected whenever the pin

voltage falls below VBOP and the IC is pushed into

Stand-by mode. Subsequently the pin has to

exceed VBOP(EN) for the IC to exit Stand-by and

resume normal operation.

Pin OVP/EN: The OVP/EN pin is connected to the

non-inverting input of the OVP(OVP) overvoltage

comparator shown in the block diagram and thus is

used to detect output overvoltage situations. The

output voltage information is communicated to the

OVP pin using a resistive divider. This pin also

serves the second purpose of an ENABLE pin. The

OVP/EN pin can be used to activate the IC into

“micropower sleep” mode by pulling the voltage on

this pin below the VSLEEP threshold. The OVP/EN

pin can be used to activate the IC into “micropower

sleep” mode by pulling the voltage on this pin below

the VSLEEP threshold.

Pin VFB: The converter output voltage is sensed

via a resistive divider and fed into this pin. VFB pin

is the inverting input of the output voltage error

amplifier. The non-inverting input of this amplifier is

connected to an internal 5V reference. The

impedance of the divider string must be low enough

that it does not introduce substantial error due to the

input bias currents of the amplifier, yet high enough

to minimize power dissipation. Typical value of

external divider impedance will be 2MΩ. The VFB

pin is also connected to the non-inverting input of

the OVP(VFB) overvoltage comparator as shown in

the block diagram and is used to detect output

overvoltage situations. Finally, VFB pin is also the

inverting input to the Open Loop comparator. The IC

is held in Stand-by Mode whenever VFB pin voltage

is below VOLP threshold. IC current consumption is

a few mA in this mode.

Pin VCC: This is the supply voltage pin of the IC

and sense node for the undervoltage lock out circuit.

It is possible to turn off the IC by pulling this pin

below the minimum turn off threshold voltage,

VCC(UVLO) without damage to the IC. This pin is

not internally clamped.

Pin GATE: This is the gate drive output of the IC.

This drive voltage is internally clamped to 13V(Typ)

and provides a drive current of ±0.75A peak with

matched rise and fall times.

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