ALTAIR05T-800 STMicroelectronics, ALTAIR05T-800 Datasheet - Page 21

• Manufacturer Part Number: ALTAIR05T-800
• Description: IC PRIMARY SWITCHING REG 16NSOIC
• Manufacturer: STMicroelectronics

Specifications of ALTAIR05T-800

• Output Isolation: Isolated
• Voltage - Input: 11.5 ~ 23 V
• Voltage - Output: 800V
• Power (watts): 900mW
• Operating Temperature: -25°C ~ 125°C
• Package / Case: 16-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ALTAIR05T-800
5.10
5.11
Hiccup mode OCP
The device is also protected against short circuit of the secondary rectifier, short circuit on
the secondary winding or a hard-saturated flyback transformer. A comparator monitors
continuously the voltage on the R
exceeds 1 V.
To distinguish an actual malfunction from a disturbance (e.g. induced during ESD tests), the
first time the comparator is tripped the protection circuit enters a “warning state”. If in the
subsequent switching cycle the comparator is not tripped, a temporary disturbance is
assumed and the protection logic is reset in its idle state; if the comparator is tripped again a
real malfunction is assumed and the device is stopped.
This condition is latched as long as the device is supplied. While it is disabled, however, no
energy is coming from the self-supply circuit; hence the voltage on the V
and cross the UVLO threshold after some time, which clears the latch. The internal start-up
generator is still off, then the V
V
frequency intermittent operation (Hiccup-mode operation), with very low stress on the power
circuit. This special condition is illustrated in the timing diagram of
Figure 19. Hiccup-mode OCP: timing diagram
Layout recommendations
A proper printed circuit board layout is essential for correct operation of any switch-mode
converter and this is true for the ALTAIR05T-800 as well. Careful component placing, correct
traces routing, appropriate traces widths and compliance with isolation distances are the
major issues. In particular:
●
●
CC
V
SOURCE
Vcc
Vcc
Vcc
capacitor is charged again and the device restarted. Ultimately, this results in a low-
Vcs
The compensation network should be connected as close as possible to the COMP
pin, maintaining the trace for the GND as short as possible
Signal Ground should be routed separately from power ground, as well from the sense
resistor trace.
V
V
CC
DS
OFF
rest
ON
dis
1 V
Secondary diode is shorted here
CC
Doc ID 17957 Rev 1
voltage still needs to go below its restart voltage before the
SENSE
and activates a protection circuitry if this voltage
Two switching cycles
Application information
Figure
CC
19.
capacitor decays
21/28
t
t
t