L6599ATD STMicroelectronics, L6599ATD Datasheet - Page 16

• Manufacturer Part Number: L6599ATD
• Description: IC RESONANT CONVRTR CTRLR 16SOIC
• Manufacturer: STMicroelectronics

Specifications of L6599ATD

• Applications: Resonant Converter Controller
• Voltage - Supply: 8.85 V ~ 16 V
• Current - Supply: 3.5mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (3.9mm Width)
• Number Of Outputs: Single Output
• Output Voltage: 13.3 V
• Switching Frequency: 200 KHz
• Duty Cycle (max): 52 %
• Operating Supply Voltage: 8.85 V to 16 V
• Supply Current: 3.5 mA
• Maximum Operating Temperature: + 150 C
• Minimum Operating Temperature: - 40 C
• Fall Time: 30 ns
• Mounting Style: SMD/SMT
• Rise Time: 60 ns
• For Use With: 497-10542 - BOARD EVAL BASED ON L6599
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Input: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Application information
16/31
Figure 7.
Essentially, RF
burst-mode operation. Once fixed f
Equation 3
Note that, unlike the f
f
transformer's peak currents are low enough not to cause audible noise.
The resonant converter's switching frequency, however, depends also on the input voltage.
Therefore, in cases where there is quite a large input voltage range with the circuit of
Figure 7
the arrangement shown in
is added to the voltage applied to the STBY pin. Due to the strongly non-linear relationship
between switching frequency and input voltage, it is more practical to find empirically the
right amount of correction R
should be taken to choose a total value of R
the effect on the LINE pin voltage (see
Whichever circuit is used, its operation can be described as follows. As the load falls below
the value Pout
voltage on the STBY pin (V
outputs low, so that both MOSFETs of the half-bridge leg are in an OFF-state. The voltage
V
it exceeds 1.29 V, the IC starts switching again. After a while, V
response to the energy burst and stops the IC. In this way the converter works in a burst-
mode fashion with a nearly constant switching frequency. A further load decrease then
causes a frequency reduction, which can go down to even a few hundred hertz. The timing
diagram of
small capacitor (typically in the hundred pF range) from the STBY pin to ground, placed as
close to the IC as possible to reduce switching noise pick-up, helps get clean operation.
To help the designer meet energy saving requirements even in power-factor-corrected
systems, where a PFC pre-regulator precedes the DC-DC converter, the L6599AT allows
the PFC pre-regulator to be turned off during burst-mode operation, thereby eliminating the
max
STBY
is associated to a load Pout
now increases as a result of the feedback reaction to the energy delivery stop and, as
a, the value of Pout
Figure 8
Burst-mode implementation:
a) narrow input voltage range; b) wide input voltage range
B
max
the frequency tries to exceed the maximum programmed value f
defines the switching frequency f
illustrates this kind of operation, showing the most significant signals. A
max
considered in the previous section (“
Figure 7
STBY
B
A
changes considerably. In this case it is recommended to use
/ (R
Doc ID 15534 Rev 3
) falls below 1.24 V. The IC then stops with both gate-drive
B
A
greater than the minimum. Pout
max
b, where the information on the converter's input voltage
+ R
RF
, RF
B
Section 6.6: Line sensing function
max
) needed to minimize the change of Pout
max
=
A
3
8
+ R
is derived from the relationship:
f
f
RF
max
min
B
that is much greater than R
min
max
−
1
above which the L6599AT enters
Section 6.1: Oscillator
STBY
B
is such that the
goes down again in
).
C
max
to minimize
B
. Care
L6599AT
and the
“), here