NXP Semiconductors
TEA1733T
GreenChip SMPS control IC
7.9 Current mode control (ISENSE pin)
Current mode control is used for its good line regulation.
The primary current is sensed by the ISENSE pin across an external resistor R9 (see
Figure 3) and compared with an internal reference voltage. The internal reference voltage
is proportional to the CTRL pin voltage (see Figure 6).
0.6
Vsense(max)
(V)
0.4
frequency
reduction
0.2
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0
0
1
2
3
4
VCTRL (V)
Fig 6. Peak current control using pin ISENSE
Leading edge blanking prevents false triggering due to capacitive discharge when
switching on the external power switch (see Figure 7).
tleb
Vsense(max)
VISENSE
Fig 7. Leading edge blanking using pin ISENSE
t
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7.10 Overpower or high/low line compensation
(VINSENSE and ISENSE pins)
The overpower compensation function can be used to realize a maximum output power
which is nearly constant over the full input mains.
The overpower compensation circuit measures the input voltage on the VINSENSE pin
and outputs a proportionally dependent current on the ISENSE pin. The DC voltage
across the soft start resistor limits the maximum peak current on the current sense
resistor.
At low output power levels the overpower compensation circuit is switched off
(See Figure 8).
TEA1733T
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 7 — 11 July 2013
© NXP B.V. 2013. All rights reserved.
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