APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH SHANNON ROAD • TUCSON, ARIZONA 85741 • USA • APPLICATIONS HOTLINE: 1 (800) 546-2739

4

EB03

OPERATING

CONSIDERATIONS

POWER SUPPLY REQUIREMENTS

SUPPLY

VOLTAGE

MAX CURRENT

HV1

50V to 200V

5A, continuous, 10A peak

HV2

50V to 200V

5A, continuous, 10A peak

HV3

50V to 200V

5A, continuous, 10A peak

10V to 20V

10mA

10V to 20V

10mA

10V to 20V

10mA

4.5 to 20V

10mA

HV1, HV2, and HV3 may be used independently, or may

compatible with the input logic. If a high voltage logic such as

requires a 5V±10% supply

SPECIAL CONSIDERATIONS

GENERAL

The EB03 is designed to give the user maximum flexibility

in a digital or DSP based motion control system. Thermal,

overvoltage, overcurrent, and crossfire protection circuits are

part of the user’s design.

Users should read Application Note 1, "General Operating

Considerations;” and Application Note 30, “PWM Basics”

for much useful information in applying this part. These

Application Notes are in the “Power Integrated Circuits Data

Book” and on line at www.apexmicrotech.com.

GROUNDING AND BYPASSING

As in any high power PWM system, grounding and

bypassing are one of the keys to success. The EB03 is

capable of generating 2 kW pulses with 40 n-second rise and

fall times. If improperly grounded or bypassed this can cause

horrible conducted and radiated EMI.

In order to reduce conducted EMI, the EB03 provides a

separate power ground, named HVRTN, for each high voltage

supply. These grounds are electrically isolated from the logic

ground and each other. This isolation eliminates high current

ground loops. However, more than 5V offset between the

grounds will destroy the EB03. Apex recommends back

to back high current diodes between logic and power

grounds; this will maintain isolation but keep offset at a

safe level. All grounds should tie together at one common

point in the system.

In order to reduce radiated EMI, Apex recommends a 50 µF

or larger capacitor between HV and HVRTN. This capacitor

should be a switching power grade electrolytic capacitor

with ESR rated at 20 kHz. This capacitor should be placed

physically as close to the EB03 as possible.

However, such a capacitor will typically have a few

hundred milli-ohms or so ESR. Therefore, each section

must also be bypassed with a low ESR 1µF or larger

ceramic capacitor.

In order to minimize radiated noise it is necessary to

minimize the area of the loop containing high frequency

This data sheet has been carefully checked and is believed to be reliable, however, no responsibility is assumed for possible inaccuracies or omissions. All specificiations are subject to change without notice.

EBO3U REV. B JANUARY 2001 © 2001 Apex Microtechnology Corporation

current. (The size of the antenna.) Therefore the 1µF ceramic

capacitors should bypass each HV to its return right at

the pins the EB03.

SHOOT THROUGH PROTECTION

Power FETs have a relatively short turn on delay, and a

longer turn off delay. Therefore, if the turn on input to an FET

in a half bridge circuit is applied simultaneously with the turn

off input to the other FET in that half bridge, there will be a time

when both FETs are simultaneoulsy on. This "shoot through

condition" will short the power rails through the FETS, causing

excessive power dissipation and a very high EMI.

To avoid the shoot through condition the turn on of one FET

must be delayed long enough for the other FET in the same

half bridge to have completely turned off.

A delay of at least .5 µ-seconds is required for the EB03.This

delay is required for both the Hin and Lin inputs.

PROTECTION CIRCUITS

The EB03 does not include protection circuits.

However, there is a shut down input which will turn off all

FETs when at logic “1”. This input may be used with user

designed temperature sensing and current sensing circuits

to shut down the FETs in the event of a detected unsafe

condition. This is recommended since the FETs may be

turned off this way even if the normal input logic or DSP

programming is faulty.

START UP CONSIDERATIONS

The lower rail FET in the half bridge must be turned on

for at least 2 µ-seconds to charge the bootstrap capacitor

before the top rail FET can be turned on. This must be done

no more than 330 µ-seconds prior to turning on the top rail

FET. However, a grounded load will also charge the bootstrap

capacitor. Therefore this consideration may be ignored when

driving a grounded load.

An internal floating supply is used to enhance the operation

of the bootstrap bias circuit. This allows the top rail FETs to

be held on indefinitely once turned on.

HEATSINK

The EB03 should be provided with sufficient heatsink to

dissipate 40 watts when operating at 200V, 5A, 50kHz, 1000pf

load capacitance per section, and 3 sections simultaneously

providing maximum current.

up to 9.45 watts per half bridge and switching losses of

about 3.72 watts per half bridge. The conduction losses

are proportional to HV supply voltage, total capacitance,

and switching frequency.