tea1733mt NXP Semiconductors, tea1733mt Datasheet - Page 9

• Manufacturer Part Number: tea1733mt
• Description: Tea1733mt Greenchip Smps Control Ic
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TEA1733MT
Preliminary data sheet
7.12 Low power operation
7.11 Soft start-up (ISENSE pin)
At low output power levels the overpower compensation circuit is switched off.
A soft start is made to prevent audible noise during start-up or a restart condition. Before
the converter starts, the soft start capacitor C6 (see
charged. When the converter starts switching, the primary peak current slowly increases
as the soft start capacitor discharges through the soft start resistor (R6, see
The soft start time constant is set by the soft start capacitor value chosen. The soft start
resistor value must also be taken into account, but this value is typically defined by the
overpower compensation (see
In low power operation switching losses are reduced by lowering the switching frequency.
The converter switching frequency is reduced and the peak current is set to 25 % of the
maximum peak current (see
Fig 8.
Fig 9.
Frequency control
Overpower compensation
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 4 February 2011
I
ISENSE
frequency
switching
(μA)
1.7
(kHz)
2
f
Figure 6
sw
Section
0.68
and
1
7.10).
Figure
1
2
9).
Figure
V
VINSENSE
V
CTRL
3
2
014aaa934
(V)
014aaa933
3) on the ISENSE pin is
GreenChip SMPS control IC
(V)
TEA1733MT
4
© NXP B.V. 2011. All rights reserved.
Figure
3).
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