VCC - is the low voltage supply for all the internal logic and

drivers. A 0.1uF ceramic capacitor in parallel with a 10uF

tantalum capacitor is recommended bypassing for the VCC-

VSS pins.

VSS - is the low voltage supply return pin and the input logic

return reference. All logic input and logic output is referenced

to this pin. This pin can vary ± 5V from the AV-,BV-,CV-/

ISENSE power return pin without affecting any of the logic

functions.

AØHIN, BØHIN, CØHIN - are low active logic inputs for signal-

ling the corresponding phase high-side switch to turn on. The

input levels are 5V CMOS or TTL compatible. Typical propa-

gation delays are around 600nS.

AØLIN, BØLIN, CØLIN - are low active inputs for signalling

the corresponding phase low-side switch to turn on. The in-

put levels are 5V CMOS or TTL compatible. Typical propaga-

tion delays are around 600nS.

ITRIP - is an analog input pin for sensing current flowing from

the AV-,BV-,CV-/ISENSE pin through a sense resistor to the

high power ground. A 0.485 volt level at this pin with re-

spect to VSS will signal an overcurrent condition and shut

down all output switching. Bringing the voltage below this

point (100 mV hysteresis) will remove the shutdown condi-

tion, and leaving the low-side logic inputs simultaneously high

(de-activated) for 10uS will restore normal operation.

AV+,BV+,CV+ - are the connections from the tops of the

three half bridges to the high voltage positive rail. Connec-

tions must be made individually from each pin to the rail, with

enough current-handling capability for the load. Proper power

supply bypassing must be connected to these three pins and

the Vss connections for proper filtering. This bypassing must

be done as close to the hybrid as possible.

AV-,BV- - are the connections from the bottoms of the AØ

and BØ half bridges to the return of the high voltage negative

rail.

These pins should be tied to the CV-/ISENSE with as

short a connection as possible.

CV-/ISENSE - is the connection from the bottom of the CØ

half bridge to the return of the high voltage negative rail. There

should be a connection to AV- and BV- here. If there is cur-

rent sensing, then a sense resistor should go between this

point and the return of the high voltage supply. If no sensing

is desired, then this point should connect to Vss, the negative

rail of the high voltage supply and any high voltage bypass

capacitance.

AØ, BØ, CØ - are the pins connecting the 3 phase bridge

switch outputs.

APPLICATION NOTES

PROTECTION

MSK4357 PIN DESCRIPTION

All logic inputs use a 300nS filter. A pulse width below this

will get ignored.

VCC voltage below the cutoff level of 8.65 volts will reset all

switch outputs off and ignore subsequent logic inputs until

VCC is restored.

Undervoltage lockout of the internal drivers for the high-side

switches also occurs at 8.65 volts.

This may occur if the

high-side output gets switched at greater than 25 kHZ with-

out switching the low-side. The internal power supply for the

high-side switch will sag too low for adequate switching. Ei-

ther slow down the PWM rate or PWM the low-side switches

instead.

Switching a low-side logic input while the corresponding phase

high-side logic input is activated will turn off both switches.

The opposite condition is also true. This is cross-conduction

lockout and will occur any time low and high-side inputs for a

phase are activated at the same time.

A 2uS deadtime is automatically inserted between high and

low-side output switching to allow complete turn-off of each

switch so no overlap will occur.

An overcurrent condition detected by the ITRIP pin will shut

down all output switches until the overcurrent condition is

removed and all three low-side logic inputs are held high for

10uS, then normal operation will resume.

ITRIP has a 400nS leading edge blanking time after switching

to ignore any switching current transients.

TYPICAL OPERATION

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-

-

-

-

-

-

Rev. I 6/04

3

EXAMPLE:

FOR 20 AMP LIMIT:

R-SENSE = 0.050 OHMS

R-SENSE VOLT = 1 VOLT

R1 = 51.5 OHMS

R2 = 48.5 OHMS

FIGURE 1

GROUNDING, BYPASSING, CURRENT SENSE