IR21141SS datasheet(12/34 Pages) IRF

12 / 34 page

IR21141/IR22141SSPbF

www.irf.com

1 Features Description

1.1 Start-Up Sequence

At power supply start-up, it is recommended to keep the

FLT_CLR pin active until the supply voltages are

properly established. This prevents spurious diagnostic

signals being generated.

When the bootstrap supply topology is used for

supplying the floating high side stage, the following start-

up sequence is recommended (see also Fig. 12):

Set VCC,

Set FLT_CLR pin to HIGH level,

Set LIN pin to HIGH level and charge the

bootstrap capacitor,

Release LIN pin to LOW level,

Release FLT_CLR pin to LOW level.

VCC

FLT_CLR

LIN

Figure 12

Start-Up Sequence

A minimum 15 µs LIN and FLT-CLR pulse is required.

A minimum supply voltage of 8V is recommended for the

driver to operate safely under switching conditions at VS

pin. At lower supply the gate driving capability decreases

and might become not sufficient to counteract switching

charge injected to the outputs.

1.2 Normal Operation Mode

After the start-up sequence has completed, the device

becomes fully operative (see grey blocks in the State

Diagram).

HIN

and

LIN

produce

driver

outputs

switch

accordingly, while the input logic monitors the input

signals and deadtime (DT) prevent shoot-through events

from occurring.

1.3 Shutdown

The system controller can asynchronously command the

Hard Shutdown (HSD) through the 3.3 V compatible

CMOS I/O FAULT/SD pin. This event is not latched.

In a multi-phase system, FAULT/SD signals are or-ed so

the controller or one of the gate drivers can force the

simultaneous shutdown of the other gate drivers through

the same pin.

1.4 Fault Management

The IR21141/IR22141 is able to manage supply failure

(undervoltage lockout) and transistor desaturation (on

both the low and high side switches).

1.4.1 Undervoltage (UV)

The undervoltage protection function disables the

driver’s output stage which prevents the power device

from being driven when the input voltage is less than the

undervoltage threshold. Both the low side (VCC supplied)

and the floating side (VBS supplied) are controlled by a

dedicate undervoltage function.

undervoltage

event

the

VCC

(when

VCC < UVVCC-) generates a diagnostic signal by forcing

the FAULT/SD pin low (see FAULT/SD section and Fig.

14). This event disables both the low side and floating

drivers and the diagnostic signal holds until the

undervoltage condition is over. The fault condition is not

latched and the FAULT/SD pin is released once VCC

becomes higher than UVVCC+.

The VBS undervoltage protection works by disabling only

the floating driver. Undervoltage on VBS does not prevent

the low side driver from activating its output nor does it

generate diagnostic signals. The VBS undervoltage

condition (VBS < UVVBS-) latches the high side output

stage in the low state. VBS must exceed the UVVBS+

threshold to return the device to its normal operating

mode. To turn on the floating driver, HIN must be re-

asserted high (rising edge event on HIN is required).

1.4.2 Power Devices Desaturation

Different causes can generate a power inverter failure

(phase

and/or

rail

supply

short-circuit,

overload

conditions induced by the load, etc.). In all of these fault

conditions, a large increase in current results in the

IGBT.

The IR21141/IR22141 fault detection circuit monitors the

IGBT emitter to collector voltage (VCE) (an external high

voltage diode is connected between the IGBT’s collector

and the ICs DSH or DSL pins). A high current in the

IGBT may cause the transistor to desaturate; this

condition results in an increase of VCE.

Once in desaturation, the current in the power transistor

can be as high as 10 times the nominal current.

Whenever the transistor is switched off, this high current

generates relevant voltage transients in the power stage

that need to be smoothed out in order to avoid

destruction (by over-voltage). The gate driver is able to

control the transient condition by smoothly turning off the

desaturated transistor with its integrated soft shutdown

(SSD) protection.

1.4.3 Desaturation Detection: DSH/L Function

Figure 13 shows the structure of the desaturation

sensing and soft shutdown block. This configuration is

the same for both the high and low side output stages.

IR21141SS Datasheet(PDF) 12 Page - International Rectifier

IR21141SS Datasheet(HTML) 12 Page - International Rectifier

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

Datasheet Download

Link URL