tea1781 NXP Semiconductors, tea1781 Datasheet - Page 18

• Manufacturer Part Number: tea1781
• Description: Greenchip Pc Secondary Control Ics
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TEA1781_82_1
Preliminary data sheet
The total output current (equal to I
across the output inductor, using the series resistance of the output inductor. The 12V2
output current is measured using a series resistance. Subtracting these two then gives the
12V1 output current.
Both output currents are then compared to the I
currents exceeds the I
mode.The system supposes the extra series resistance to be half the value of the inductor
series resistance. The I
to 180 mV for 12V1, and 90 mV for 12V2.
Applying a series resistance of 5 m and an inductor series resistance of 10 m , the
default OCP levels of the 12 V outputs are set at 18 A. The OCP levels of the 12 V outputs
can be increased by a resistor from pin OCP_12V to ground and decreased by a resistor
from pin VDD to pin OCP_12V.
The 3.3 V and 5 V OCP can be adjusted externally, whereas the system assumes
identical 3.3 V and 5 V OCP levels, see
an RC network across the output inductor, making use of the inductor series resistance. If
either the 5 V or 3.3 V output exceeds its OCP setting, the system enters the Protection
mode.
Fig 15. 12 V output overcurrent protection
Rev. 01 — 13 February 2009
ocp
TEA1782
ocp
CS_12V
(12 V output) setting, the system will enter the Protection
(12 V output) has a default setting of 100 A, corresponding
out_12V1
Protection 12 V
VOUT_12V1
V
ovp(VOUT_12V1)
Figure
+ I
TEA1781T; TEA1782T
out_12V2
16. The output currents are measured via
ocp
Protection mode
VOUT_12V2
GreenChip PC secondary control ICs
I
V
V
VOUT_12V2
(12 V output) setting. If one of these
VOUT_12V1
VOUT_12V2
) is measured via an RC network
I
VOUT_12V
I
ocp_12V
I
or 2
VOUT_12V
I
VOUT_12V2
V
OCP_12V
ref(OCP)
2
I
VOUT_12V2
> I
ocp_12V
© NXP B.V. 2009. All rights reserved.
014aaa195
> I
ocp_12V
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