EVL90WADP-LLCSR STMicroelectronics, EVL90WADP-LLCSR Datasheet - Page 25

• Manufacturer Part Number: EVL90WADP-LLCSR
• Description: EVAL BOARD PORTABLE PWR SUPPLY
• Manufacturer: STMicroelectronics
• Type: Power Factor Correctionr

Specifications of EVL90WADP-LLCSR

• Main Purpose: AC/DC, Primary and Secondary Side with PFC
• Outputs And Type: 1, Isolated
• Power - Output: 90W
• Voltage - Output: 19V
• Current - Output: 4.75A
• Voltage - Input: 90 ~ 264VAC
• Regulator Topology: Boost
• Frequency - Switching: 130kHz
• Board Type: Fully Populated
• Utilized Ic / Part: L6563H, L6599A, SRK2000
• Input Voltage: 90 V to 264 V
• Output Voltage: 19 V
• Dimensions: 65 mm x 155 mm
• Product: Power Management Modules
• Supply Current: 4.75 A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: L6563H, L6599A, SRK2000
• Other names: 497-10377

L6599A
Figure 28. Current sensing techniques: a) with sense resistor, b) “lossless”,
The L6599A is equipped with a current sensing input (pin 6, ISEN) and a sophisticated
overcurrent management system. The ISEN pin is internally connected to the input of a first
comparator, referenced to 0.8 V, and to that of a second comparator referenced to 1.5 V. If
the voltage externally applied to the pin by either circuit in
comparator is tripped and this causes an internal switch to be turned on and discharge the
soft-start capacitor C
frequency and thereby limit energy transfer. The discharge will go on until the voltage on the
ISEN pin has dropped by 50 mV; this, with an averaging time in the range of 10/f
an effective frequency rise. Under output short circuit, this operation results in a nearly
constant peak primary current.
It is normal that the voltage on the ISEN pin may overshoot above 0.8 V; however, if the
voltage on the ISEN pin reaches 1.5 V, the second comparator will be triggered, the L6599A
will shutdown and latch off with both the gate-drive outputs and the PFC_STOP pin low,
hence turning off the entire unit. The supply voltage of the IC must be pulled below the
UVLO threshold and then again above the start-up level in order to restart. Such an event
may occur if the soft-start capacitor C
or in case of transformer’s magnetizing inductance saturation or a shorted secondary
rectifier.
In the circuit shown in
low-side MOSFET is used, note the particular connection of the resonant capacitor. In this
way the voltage across Rs is related to the current flowing through the high-side MOSFET
and is positive most of the switching period, except for the time needed for the resonant
current to reverse after the low-side MOSFET has been switched off. Assuming that the time
constant of the RC filter is at least ten times the minimum switching frequency f
approximate value of Rs can be found using the empirical equation:
Equation 6
where I
and the primary winding of the transformer, which is related to the maximum load and the
minimum input voltage.
Crpkx
with capacitive shunt
is the maximum desired peak current flowing through the resonant capacitor
SS
Figure 28
(see
Section 7.3: Soft-start
Doc ID 15308 Rev 5
Rs
a, where a sense resistor Rs in series to the source of the
=
SS
Vs
I
Crpkx
pkx
is too large, so that its discharge is not fast enough
≈
5
I
Crpkx
⋅
0
8 .
). This will quickly increase the oscillator
≈
I
Crpkx
4
Figure 28
Application information
exceeds 0.8 V the first
min
min
, ensures
, the
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