ALTAIR05T-800TR STMicroelectronics, ALTAIR05T-800TR Datasheet - Page 19

• 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
Figure 17
Figure 17. CDC block: internal schematic
During CV regulation, as the CDC block is capable of sinking current, a resistor connect
between its output and ZCD/FB pin allows to increase the CV setpoint, by providing a
voltage lower than the internal reference voltage by an amount proportional to the average
load current.
If R
following equation:
In this equation R
The CDC block acts as an outer control loop with a positive feedback that changes the CV
setpoint. As such, it can impact on the overall system’s stability. In order to avoid any issue
that could make unstable the loop, the CV setpoint response time must be much slower than
that of the inner voltage loop.
For this purpose the CDC block is designed with a time response of a few ten ms. For the
same reason, the minimum voltage on CDC pin is bottom limited at to 2.25 V.
If the function is not required, the pin can be connected to ground or left open.
CABLE
Rf b
is the total cable resistance, the resistor value can be calculated by using the
presents the internal schematic.
Rcdc
ZCD/FB
CABLE
CDC
R
CDC
is the total resistance of the output cable.
=
F B Block
LOGIC
2
------------------------ -
CDC
⋅
N
Rzcd
Viref
Doc ID 17957 Rev 1
N
PRI
SEC
COMP
⋅
Vr ef
N
--------------
N
To C V Compar ator
SEC
AUX
⋅
R
------------------------------------------- -
SENSE
R
CABLE
N pr i
N aux
⋅
R
ZCD
Nsec
Dsec
Application information
Vout_reg
(5)
Cout
Rcable/2
R cable/ 2
Vout
GND
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