AN10881
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© NXP B.V. 2011. All rights reserved.
Application note
Rev. 2 — 26 September 2011
54 of 102
NXP Semiconductors
AN10881
TEA1713 resonant power supply control IC with PFC
8.6 SSHBC/EN soft-start and enable
The SSHBC/EN pin provides the following three functions:
•
It enables the PFC (> 1.2 V) and PFC plus HBC (> 2.2 V)
•
It performs an HBC frequency sweep during soft-start from 3.2 V to 8 V
•
It provides frequency control during protection
Seven internal current sources operate the frequency control depending on the required
action.
•
Soft-start + OverCurrent Protection: high/low charge (160
A/40
A) + high/low
discharge (160
A/40
A)
•
Capacitive mode regulation: high/low discharge (1800
A/440
A)
•
General: bias discharge (5 mA)
8.6.1 Switching ON and OFF using an external control function
The SSHBC/EN can be used to switch the converters on and off using an external control
function.
This function is often driven by a microcontroller from the secondary side of the OPTO
coupler. The main power supply (PFC+HBC) can be switched off for Standby mode and
switched on for normal operation. A separate standby supply must supply the
microcontroller functions during Standby mode. It is also possible to switch/keep off the
HBC and only have the PFC operational.
Fig 32. SSHBC: overview of sources, clamps and levels
001aal042
SSHBC/EN 22
1360
μ
A
440
μ
A
120
μ
A
40
μ
A
120
μ
A
40
μ
A
5
μ
A
high CMR
disable
1.2 V
ENABLE PFC
COMP
low CMR
high SoSt
low SoSt
bias
TEA1713
2.2 V
ENABLE HBC
COMP
FREQUENCY
CONTROL
8 V
3.2 V
42
μ
A
3.0 V
8.4 V