L6599 STMicroelectronics, L6599 Datasheet - Page 16

• Manufacturer Part Number: L6599
• Description: High-voltage resonant controller
• Manufacturer: STMicroelectronics

Specifications of L6599

• Dimensions (l/w/h): 132 mm / 52 mm / 22 mm
• Universal Ac Mains Range: 90 VAC to 264 VAC
• High Output Power: 90 W (4.74 A, 19 VDC)
• Very Low Output Noise And Ripple: less than 300 m VP-P
• Very Low Standby Power: less than 0.5 W at 264 V
• Hiccup Mode: Auto recovery with SCP
• Latch Mode: OVP acts while VOUT > 29 VDC

Application information
7.1
16/36
Oscillator
The oscillator is programmed externally by means of a capacitor (CF), connected from pin 3
(CF) to ground, that will be alternately charged and discharged by the current defined with
the network connected to pin 4 (RF
about 2 mA source capability and the higher the current sourced by the pin is, the higher the
oscillator frequency will be. The block diagram of
circuit that explains the operation.
The network that loads the RFmin pin generally comprises three branches:
1.
2.
3.
Figure 22. Oscillator's internal block diagram
The following approximate relationships hold for the minimum and the maximum oscillator
frequency respectively:
R
Fmin
A resistor RF
operating frequency;
A resistor RF
phototransistor that transfers the feedback signal from the secondary side back to the
primary side; while in operation, the phototransistor will modulate the current through
this branch - hence modulating the oscillator frequency - to perform output voltage
regulation; the value of RF
be operated at when the phototransistor is fully saturated;
An R-C series circuit (C
to set up a frequency shift at start-up (see
contribution of this branch is zero during steady-state operation.
C
R
SS
SS
max
min
R
Fmax
connected between the pin and ground that determines the minimum
connected between the pin and the collector of the (emitter-grounded)
RFmin
SS
4
2 V
max
f
+ R
L6599
max
SS
min
determines the maximum frequency the half-bridge will
+
-
=
0.9V
f
1 V
min
) connected between the pin and ground that enables
-----------------------------------------------------------------
3 CF
). The pin provides an accurate 2 V reference with
⋅
3.9V
4 V
=
------------------------------------ -
3 CF RF
⋅
⋅
+
+
-
-
(
RF
Chapter 7.3:
I
1
⋅
1
min
R
Figure 22
S
R
||
min
RF
Q
max
)
shows a simplified internal
Soft-start). Note that the
K
M
2·K
·I
R
M
·I
R
K
M
·I
R
3
CF
L6599
CF