AN2359 datasheet(12/18 Pages) STMICROELECTRONICS

12 / 18 page

Application example nº 2

AN2359

12/18

Figure 14.

VIPer22A temperature at maximum load

Application example nº 2

In this second example, the Buck-Boost is modified in order to have –24V/-5Voutputs

voltages in a 4W application. In Table 7. the main specifications of the power supply are

listed. The schematic of the circuit and the component list are shown in Figure 15. and in

Table 8. respectively.

The –24V output voltage allows to supply the VIPer directly from the feedback path, saving

the cost of a high voltage diode. Even in this case, the feedback regulation is connected to

VOUT2 by means of Q1 transistor and DZ1 zener diode. The output inductor, with

intermediate tap for VOUT2, is provided by PULSE (PFM0250 type) with the following

features:

●

L1-3 = 510µH ±10%;

●

N1-3 / N2-3 = 3.81 ± 2%;

●

R1-2 = 560mW (max);

●

R2-3 260ΩW (max).

Table 7.

SMPS specifications

Specification

Value

Input voltage range, VIN

88 - 265VAC

Output voltage VOUT1

-24V

Output voltage VOUT2

-5V

Maximum output current IOUT1

100mA

Maximum output current IOUT2

300mA

Maximum output power

AN2359 Datasheet(PDF) 12 Page - STMicroelectronics