AN1061 APPLICATION NOTE

2/21

2 DEVICE DESCRIPTION

For a better understanding of the device and its working principles, a short description of the

main building blocks is given here below, with packaging options and complete block diagram.

Figure 1 shows the two packaging options, with the pin function assignments.

Figure 2. Pins Connection.

Figure 3. Block Diagram

3 POWER SUPPLY & VOLTAGE REFERENCE

The device is provided with an internal stabilised power supply (of about 12V typ. ) that powers

the analog and digital control blocks and the bootstrap section.

From this preregulator, a 3.3V reference voltage ±2%, is internally available.

Oscillator and voltage feedforward.

Just one pin is necessary to implement the oscillator function, with inherent voltage feedfor-

ward.

GND

SS_INH

OSC

OUT

1

3

2

4

VCC

BOOT

COMP

FB

8

7

6

5

D97IN595

N.C.

GND

SS_INH

OSC

OUT

N.C.

OUT

N.C.

N.C.

N.C.

BOOT

VCC

COMP

FB

N.C.

N.C.

1

3

2

4

5

6

7

8

14

13

12

11

10

9

15

16

D97IN596

INHIBIT

SOFTSTART

VOLTAGES

MONITOR

THERMAL

SHUTDOWN

E/A

PWM

3.3V

OSCILLATOR

R

S

Q

INTERNAL

REFERENCE

INTERNAL

SUPPLY

3.3V

5.1V

DRIVE

CBOOT

CHARGE

CBOOT

CHARGE

AT LIGHT

LOADS

2

7

8

FB

COMP

SS_INH

3

1

4

6

5

BOOT

OSC

GND

OUT

VCC

D97IN594