UM10437 Datasheet, PDF (25/27 Pages) NXP Semiconductors – GreenChip 65 W TEA1738LT/T and TEA1703 demo board

NXP Semiconductors
UM10437
GreenChip 65 W TEA1738LT/T and TEA1703 demo board
8. Alternative circuit options
8.1 Changing the output voltage
By changing the following components, the output voltage can be changed (30 %). Refer
to the TEA1738(L)T application note for additional information on this topic. Make sure
that the Aux voltage remains within its operation limits (12.2 V  30 V typical) and is high
enough to start up (20.6 V typical).
R23/R24
The resistor divider R36 and R37 determine the output voltage based on
V_o = 2.5 V  (R36 + R37) / (R37).
C13/C14
The voltage rating of these electrolytic capacitors must be chosen to be higher than the
output voltage. Decrease the value of the capacitors for applications with a lower output
current.
8.2 TEA1703 adjustments
In this design the following items can be improved by changing the value of the inductor
L4 to 4m7H. Currently the current through opto LED M4 is too low.
• Output power level threshold to enter Standby mode is very low
• The V_CC clamp cannot sink enough current for high mains. This causes the TEA1738
to restart in Standby mode at 264 V; 60 Hz. This behavior is not recommended
The minimum output voltage in Standby mode can be adjusted using resistor R30. By
increasing resistor R30 from 330 k to 420 k, an additional < 2 mW can be saved and
the minimum output voltage will drop to 9 V.
Refer to the TEA1703 application note for adjustment information.
UM10437
User manual
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 28 February 2011
© NXP B.V. 2011. All rights reserved.
25 of 27