ALTAIR05T-800TR STMicroelectronics, ALTAIR05T-800TR Datasheet - Page 17

• Manufacturer Part Number: ALTAIR05T-800TR
• Description: Switching Converters, Regulators & Controllers 800V Off-line QR Switching Regulator
• Manufacturer: STMicroelectronics

Specifications of ALTAIR05T-800TR

• Input Voltage: 11.5 V to 23 V
• Switching Frequency: 166 KHz
• Operating Temperature Range: - 55 C to + 150 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC-16
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ALTAIR05T-800
5.6
Figure 15. Constant current operation: Switching cycle waveforms
Voltage feedforward block
The current control structure uses the voltage V
(2). Actually, the CC comparator is affected by an internal propagation delay Td, which
switches off the MOSFET with a peak current than higher the foreseen value.
This current overshoot is equal to:
Where L
It introduces an error on the calculated CC setpoint, depending on the input voltage.
The device implements a Line Feedforward function, which solves the issue by introducing
an input voltage dependent offset on the current sense signal, in order to adjust the cycle-
by-cycle current limitation.
The internal schematic is shown in
P
is the primary inductance.
Q
I
I
I
C
P
s
Doc ID 17957 Rev 1
∆I
Figure
P
=
V T
IN
I
L
CRE F
16.
⋅
P
d
T
=
−
C
V
R
to define the output current, according to
C
I
CREF
t
t
t
t
Application information
(3)
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