TEA1521T NXP Semiconductors, TEA1521T Datasheet - Page 6

• Manufacturer Part Number: TEA1521T
• Manufacturer: NXP Semiconductors

Specifications of TEA1521T

• Operating Temperature (max): 145C
• Operating Temperature (min): -40C
• Pin Count: 14
• Mounting: Surface Mount
• Package Type: SO
• Screening Level: Automotive
• Lead Free Status / Rohs Status: Compliant

NXP Semiconductors
TEA152X
Product data sheet
As soon as the oscillator voltage is high again and the secondary stroke has ended, the
circuit waits for a low drain voltage before starting a new primary stroke.
Figure 4
secondary stroke and the RC voltage.
The primary stroke starts some time before the actual valley at low ringing frequencies,
and some time after the actual valley at high ringing frequencies.
Figure 5
the output voltage V
the factor N (determined by the turns ratio of the transformer).
system switches exactly at minimum drain voltage for ringing frequencies of 480 kHz, thus
reducing the switch-on losses to a minimum. At 200 kHz, the next primary stroke is started
at 33° before the valley. The switch-on losses are still reduced significantly.
Fig 4.
shows a typical curve for a reflected output voltage N × V
shows the drain voltage together with the valley signal, the signal indicating the
A: Start of new cycle with valley switching
B: Start of new cycle in a classical PWM system
Signals for valley switching
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secondary
oscillator
stroke
valley
drain
RC
o
Rev. 04 — 14 September 2010
(see
primary
stroke
Figure
6) transferred to the primary side of the transformer with
regulation level
secondary
stroke
SMPS ICs for low-power systems
secondary
ringing
B
Figure 5
o
of 80 V. This voltage is
mgt423
A
TEA152x
© NXP B.V. 2010. All rights reserved.
shows that the
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