HA16114P Datasheet, PDF (18/38 Pages) Hitachi Semiconductor – Switching Regulator for Chopper Type DC/DC Converter

HA16114P/PJ/FP/FPJ, HA16120FP/FPJ
7.4 Examples of Intermittent Mode Timing (calculated values)
(1) T_ON
8
T_ON = T₁ × C _ON/OFF × R _B
Here, coefficient
6
T₁
=
0.69
×
1
−
1
On
duty
4
from section 7.3 (1) previously.
Example: If C_ON/OFF = 2.2 µF,
R_B = 2.2 kΩ, and the on duty
of the current limiter is 75%,
then T_ON = 13 ms.
T₁
2
00
20 40 60 80 100
(PWM) On duty (%)
Figure 7.4 Examples of Intermittent Mode Timing (1)
(2) T_OFF
T_OFF = T₂ × C_ON/OFF × (R_A + R_B)
Here, coefficient
T₂
=
ln
V_IN − V_BE
V_IN − 2V_BE
from section 7.3 (2) previously.
0.1
T₂
0.05
Example: If C_ON/OFF = 2.2 µF, R _B = 2.2 k Ω,
R_A = 390 kΩ, V_IN = 12 V,
then T_OFF = 55 ms.
0
0
10
20
30
40
V_IN (V)
Figure 7.5 Examples of Intermittent Mode Timing (2)
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