ssl1750 NXP Semiconductors, ssl1750 Datasheet - Page 12

• Manufacturer Part Number: ssl1750
• Description: Smps Control Ic For Led Drivers
• Manufacturer: NXP Semiconductors

NXP Semiconductors
SSL1750_1
Product data sheet
7.2.10 PFC open loop protection (pin VOSENSE)
7.2.7 Overcurrent protection (pin PFCSENSE)
7.2.8 Mains undervoltage lockout / brownout protection (pin VINSENSE)
7.2.9 Overvoltage protection (pin VOSENSE)
The maximum peak current is limited cycle-by-cycle by sensing the voltage across an
external sense resistor (R
measured via the pin PFCSENSE.
To prevent the PFC from operating at very low mains input voltages, the voltage on pin
VINSENSE is sensed continuously. As soon as the voltage on this pin drops below the
V
the PFC bus voltage eventually drops. The voltage on pin VOSENSE then drops below the
V
The voltage on pin VINSENSE is clamped to a minimum value,
(V
restored after a mains dropout.
An overvoltage protection circuit has been built in to prevent output overvoltage during
load steps and mains transients.
As soon as the voltage on pin VOSENSE exceeds the V
power factor correction circuit is inhibited. Switching of the PFC recommences as soon as
the voltage on VOSENSE voltage drops below the V
When the resistor between pin VOSENSE and ground is open, the overvoltage protection
is also triggered.
The power factor correction circuit does not start switching until the voltage on pin
VOSENSE is above the V
VOSENSE short situations. As pin VOSENSE draws a small input current, switching is
also inhibited when the pin is left open.
Fig 7.
stop(VINSENSE)
start(fb)
start(VINSENSE)
level and the flyback converter is also disabled.
Burst mode control
peak current
level, switching of the PFC is stopped. If the low mains situation continues,
V
envelop of
VOSENSE
V
pu(VINSENSE)
Rev. 01 — 15 September 2008
SENSE1
th(ol)(VOSENSE)
, for a fast restart as soon as the mains input voltage is
) on the source of the external MOSFET. The voltage is
level. This protects the circuit from open loop and
soft-start
ton control
ovp(VOSENSE)
SMPS control IC for LED drivers
ovp(VOSENSE)
soft-stop
V
V
burst(L)
burst(H)
014aaa019
level again.
level, switching of the
SSL1750
© NXP B.V. 2008. All rights reserved.
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