13

HIP4080 Power-up Application Information

The HIP4080 H-Bridge Driver IC requires external circuitry

to assure reliable start-up conditions of the upper drivers. If

not addressed in the application, the H-Bridge power MOS-

FETs may be exposed to shoot-through current, possibly

leading to MOSFET failure. Following the instructions below

will result in reliable start-up.

The HIP4080 does not have an input protocol like the

HIP4081 that keeps both lower power MOSFETs off other

than through the DIS pin. IN+ and IN- are inputs to a com-

parator that control the bridge in such a way that only one of

the lower power devices is on at a time, assuming DIS is low.

However, keeping both lower MOSFETs off can be accom-

plished by controlling the lower turn-on delay pin, LDEL,

while the chip is enabled, as shown in Figure 32. Pulling

through the input comparator and will keep the lower MOS-

FETs off. With the lower MOSFETs off and the chip enabled,

i.e. DIS = low, IN+ or IN- can be switched through a full

cycle, properly setting the upper driver outputs. Once this is

accomplished, LDEL is released to its normal operating

point. It is critical that IN+/IN- switch a full cycle while LDEL

is held high, to avoid shoot-through. This start-up procedure

can be initiated by the supply voltage and/or the chip enable

command by the circuit in Figure 32.

11

12

13

14

15

16

17

18

20

19

10

9

8

7

6

5

4

3

2

1 BHB

HEN

DIS

OUT

IN+

HDEL

IN-

LDEL

AHB

BHO

BLO

BLS

BHS

ALS

ALO

AHS

AHO

100K

RDEL

RDEL

0.1

µF

2N3906

ENABLE

56K

8.2V

56K

100K

FIGURE 32.

DIS

LDEL

=10ms

t1

t2

8.3V TO 9.1V (ASSUMING 5% ZENER TOLERANCE)

12V, FINAL VALUE

5.1V

NOTES:

2. Between t1 and t2 the IN+ and IN- inputs must cause the OUT pin to go through one complete cycle (transition order is not important). If

the ENABLE pin is low after the under-voltage circuit is satisfied, the ENABLE pin will initiate the 10ms time delay during which the IN+

and IN- pins must cycle at least once.

3. Another product, HIP4080A, incorporates undervoltage circuitry which eliminates the need for the above power up circuitry.

FIGURE 33. TIMING DIAGRAM FOR FIGURE 32

HIP4080