PEB 2023

PEF 2023

Functional Description

Semiconductor Group

18

08.97

Voltage Reference

The reference regulator of the PEB/F 2023 is based on a temperature compensated

bandgap. This circuitry is fully active at supply voltages (pin V

provides up to 0.5mA of load current to external circuitry at 4 volts. This reference has to

be buffered by an external capacitor (C

Sawtooth Oscillator

The oscilator frequency is programmed by the two components R

5 or 6). The oscillator timing capacitor C

by an internal 10k

Ω discharge-resistor. The rise-time of the sawtooth oscillator can be

programmed with R

At the beginning of the discharge period a positive synchronization pulse is generated at

pin SYNC. Otherwise the PEB/F 2023 can be synchronized via pin SYNC to an external

logic clock by programming the oscillator to free run at a frequency 10% lower than the

synchronization frequency. The PEB/F 2023 is synchronized by the rising edge of the

sync. signal. So multiple devices can be synchronized together by programming one

master unit for the desired frequency (only one possible interfering frequency).

Note that the frequency of the output driver is half the oscillator frequency. The switching

frequency as a function of R

Figure 9

Switching Frequency

0

50

100

150

200

250

300

350

10

20

30

40

50

60

70

80

90

100

R [ kOHM ]

10 pF

22 pF

68 pF

100 pF

220 pF

470 pF

1 nF