NXP Semiconductors
UM11762
NTS0304EUK-ARD evaluation board
4.9.2 LDO2
The programmable power supply LDO2 is realized with the adjustable voltage regulator
MIC5301 (U4), and the analog switch 74HCT4052D (U2). Similarly, the analog switch
selects the resistor divider ratio in the feedback loop of the voltage regulator (U4).
shows the output voltages of LDO2 as a function of the switch position. U1 is controlled
from the Arduino port through “MUX2_LDO2_S0” and “MUX2_LDO2_S1”, (pins 3 and 4
of Arduino connector J5). The control line “MUX2_EN_B” is connected to ground through
pull-down resistor R18. The VCC_LDOOUT2 rail feeds the VCCB power pin of U6 (the
DUT) and the VCCB pins of U8 and U10 level translators.
MUX2_LDO2_S1
MUX2_LDO2_S0
VCC_LDOOUT2
Low
Low
1.8 V
Low
High
2.5 V
High
Low
3.3 V
High
High
4.96 V
Table 3. VCC_LDOOUT2 voltages
4.9.3 The interlock
To ensure proper operation, the NTS0304E needs to comply with the following condition:
VCCA ≤ VCCB. An interlock circuit was implemented to avoid the above described
condition. The components involved in the interlock circuit are U1, U2, D3, and D4. The
voltage level applied to the enable inputs of the LDOs (U3, and U4) depends on the
voltage selection performed by the switches U1 and U2. Therefore, the LDOs are ON
only if the condition VCC_LDOUT1 ≤ VCC_LDOUT2 occurs.
shows the enable
status of the LDOs, as a function of the selected output voltages.
VCC_LDOUT2
VCC_LDOUT1
1.8 V
2.5 V
3.3 V
4.96 V
0.95 V
ON
ON
ON
ON
1.2 V
ON
ON
ON
ON
1.8 V
ON
ON
ON
ON
2.5 V
OFF
ON
ON
ON
3.3 V
OFF
OFF
ON
ON
Table 4. LDO enable status
4.10 Jumpers and test points
The board contains four jumpers and several test points.
the jumper locations and their default configurations.
located on the NTS0304EUK-ARD board.
Ref Des
Label
Default
Description
ON – SPI chain loop closed
J2
J2
ON
OFF – SPI chain loop open
J7
J7
OFF
OFF – OE Enable
Table 5. NTS0304EUK-ARD jumpers
UM11762
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User manual
Rev. 1.0 — 27 May 2022
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