PEB2023 Datasheet, PDF (15/25 Pages) Siemens Semiconductor Group – ISDN DC Converter Circuit IDCC

Calculation example: figure 7 with R_Vs = 4,7kΩ
PEB 2023
PEF 2023
Overview
V_INstart = V_ZD1 + 8 + (R_Vs ⋅ i_LVR) = 30V + 8V + (4,7kΩ ⋅ 500µA) = 40,35V
for t ≤ 100msec:
V_INmax = V_ZD1 + 100 + (R_Vs ⋅ i_Vsmax) = 30V + 100V + ( 4,7kΩ ⋅ 10mA) = 177V
for t ≤ 10msec:
V_INmax = V_ZD1 + 100 + (R_Vs ⋅ i_Vsmax) = 30V + 100V + ( 4,7kΩ ⋅ 30mA) = 271V
In this example the DC/DC converter begins operating when the input voltage exceeds
40,35V. The maximum transient input voltage is 177V / 271V for a duration of 100msec
/ 10msec. The maximum static input voltage is given by V_ZD1 + 90V = 120V, see absolute
maximum ratings.
1.7 Fast Input Undervoltage Detection
With three extra devices (D₅, D₆ and R₈, see figure 8) an undervoltage state on the input
can be detected faster than the voltage on capacitor C₆ decreases. See also chapter
„undervoltage lockout“ on page 17.
D₅
C₆ +
100µF
20%
D₆
R₈
10ΜΩ/10%
ZD
BZV55C30
R₆
10ΜΩ/10%
7
11
V_S
UV
PEB 2023
PEF 2023
GND
3
0V
Figure 8
PEB/F 2023, Fast Input Undervoltage Detection
Semiconductor Group
15
08.97