ALTAIR05T-800 STMicroelectronics, ALTAIR05T-800 Datasheet - Page 13

• 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
5.3
Figure 10. Timing diagram: normal power-up and power-down sequences
Zero current detection and triggering block
The zero current detection (ZCD) and triggering blocks switch on the power MOSFET if a
negative-going edge falling below 50 mV is applied to the ZCD/FB pin. To do so, the
triggering block must be previously armed by a positive-going edge exceeding 100 mV.
This feature is used to detect transformer demagnetization for QR operation, where the
signal for the ZCD input is obtained from the transformer’s auxiliary winding used also to
supply the IC.
Figure 11. ZCD block, triggering block
The triggering block is blanked after MOSFET’s turn-off to prevent any negative-going edge
that follows leakage inductance demagnetization from triggering the ZCD circuit
erroneously.
This blanking time is dependent on the voltage on COMP pin: it is T
= 0.9 V, and decreases almost linearly down to T
DRAIN
DRAIN
Vcc
Vcc
V
V
I
I
5.5 mA
5.5 mA
Vcc
Vcc
charge
charge
Vcc
Vcc
Start
Start
restart
restart
Vin
Vin
ON
ON
Aux
R zcd
Power-on
Power-on
Z CD/FB
R f b
110mV
60mV
CLAMP
Z CD
Doc ID 17957 Rev 1
Normal operation
Normal operation
CV mode
CV mode
+
-
BLANKIN G
Fr om CC/ CV Bloc k
TIME
BLANK
Normal operation
Normal operation
CC mode
CC mode
TU RN- ON
= 6 µs for V
LO GIC
LEB
Fr om OC P
STARTER
Application information
BLANK
COMP
S
R
Q
= 30 µs for V
= 1.3 V
Power-off
Power-off
To Dr iv er
COMP
13/28
t
t
t
t
t t
t
t t
t
t
t