AN10907
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© NXP B.V. 2010. All rights reserved.
Application note
Rev. 1 — 28 December 2010
44 of 82
NXP Semiconductors
AN10907
TEA1613T resonant power supply control IC
8.7.1 HBC overcurrent regulation
The lowest comparator levels of
0.5 V at the SNSCURHBC pin belong to the
Over-Current Regulation (OCR) level. There is a comparator for both the positive and
negative polarity. If either level is exceeded, the frequency is increased slowly. This is
accomplished by discharging the soft-start capacitor on the SSHBC/EN pin. Every time
the OCR level is exceeded, the state is latched until the next stroke and the soft-start
discharge current is enabled. When both the positive and negative OCR levels are
exceeded, the soft-start discharge current flows continuously. In this way the operating
frequency is slowly increased until the resonant current value just reaches the value
permitted by the preset.
The behavior during OCR can be observed on the SSHBC/EN pin as a resultant
regulation voltage.
When an OCR situation is present for a long time, a serious fault condition is assumed.
During OCR the protection timer is activated. The charging of the protection timer is active
approximately a half period cycle after the
0.5 V level is exceeded. If the detection levels
are continuously exceeded, the timer is charged continuously. However, if the detection
levels are only sometimes exceeded, the timer is charged accordingly. The restart state is
activated when RCPROT reaches the protection level of 4 V.
Fig 30. OCP and regulation HBC
001aal454
BOOST
COMPENSATION
CONTROL
V
SNSBOOST
HBC operational
I
boost-compensation
±
I
boost-compensation
V
BOOST
over current protection
1 V
SNSCURHBC
1.8 V
V
SNSBOOST
0
μ
A
170
μ
A
2.5 V 2.63 V
COMP
Rcc
1 k
Ω
TEA1613
over current protection
−
1 V
COMP
over current regulation
0.5 V
COMP
over current regulation
−
0.5 V
COMP
