TEA1721AT Datasheet, PDF (4/14 Pages) NXP Semiconductors – Ultra-low standby SMPS controller with integrated power switch

NXP Semiconductors
4. Pinning information
4.1 Pinning
TEA1721AT
Ultra-low standby SMPS controller with integrated power switch
Fig 2. Pinning top view
GND1 1
GND2 2
GND3 3
FB 4
7 DRAIN
TEA1721
6 SOURCE
5 VCC
001aan294
4.2 Pin description
Pin
Pin name
1
GND1
2
GND2
3
GND3
4
FB
5
VCC
6
SOURCE
7
DRAIN
-
-
I/O type
I
I
O
I
Pin description
ground
ground
ground
feedback input for voltage sensing
supply input
source for power switch
drain of power switch
high voltage spacer
5. Functional description
5.1 Start-up
The TEA1721 starts up by charging the VCC capacitor until the V_CC(start) level. The
charging current flows from the high voltage DRAIN pin via an internal start-up current
source to the VCC pin.
Once the start level has been reached the start-up current source is switched off. During
switching operation, the start-up current source remains current-less and has zero
bleeder loss.
5.2 Primary sensing
The FB input senses the reflected secondary voltage on the primary side. The FB input
has a sample and hold function that samples the FB voltage on the secondary stroke to
control the output voltage.
The sampled V_FBS voltage is the input for the TEA1721’s control loop and defines the
operating mode.
TEA1721AT
Preliminary data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 24 January 2012
© NXP B.V. 2012. All rights reserved.
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