LD6938_SER All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Objective data sheet Rev. 1 — 11 July 2013 6 of 15
NXP Semiconductors
LD6938 series
Dual low-dropout regulators, low noise, 300 mA
7. Thermal characteristics
[1] The overall R
th(j-a)
can vary depending on the board layout. To minimize the effective R
th(j-a)
, all pins must
have a solid connection to larger Cu layer areas for example to the power and ground layer. In multi-layer
PCB applications, the second layer should be used to create a large heat spreader area directly below the
LDO. If this layer is either ground or power, it should be connected with several vias to the top layer
connecting to the device ground or supply. Avoid the use of solder-stop varnish under the chip.
[2] Use the measurement data given for a rough estimation of the R
th(j-a)
in your application. The actual R
th(j-a)
value can vary in applications using different layer stacks and layouts.
8. Characteristics
Table 7. Thermal characteristics
Symbol Parameter Conditions Typ Unit
R
th(j-a)
thermal resistance from junction to
ambient
[1][2]
100 K/W
Table 8. Electrical characteristics
At recommended input voltages and T
amb
=
40
Cto+85
C; voltages are referenced to GND (ground = 0 V);
unless otherwise specified.
Symbol Parameter Conditions Min Typ Max Unit
Output voltage (pin OUT1 and OUT2)
V
do
dropout voltage I
O
=300mA; V
IN
V
O(nom)
- 240 400 mV
V
O
output voltage variation V
O
1.5 V; I
O
=1mA
T
amb
=+25C 2- +2%
30 C T
amb
+85 C 3- +3%
V
O
<1.5V; I
O
=1mA
T
amb
=+25C 3- +3%
30 C T
amb
+85 C 4- +4%
Line regulation error
V
O
/(V
O
xV
I
) relative output voltage
variation with input voltage
V
I
=(V
O(nom)
+ 1 V) to 5.5 V;
I
O
=1mA
0.1 - +0.1 %/V
V
O
/V
O
relative output voltage
variation
V
I
=(V
O(nom)
+ 1 V) to 5.5 V;
I
O
=1mA
0.33 - +0.33 %
Load regulation error
V
O
/(V
O
xI
O
) relative output voltage
variation with output current
V
I
=V
O(nom)
+1V;
1mA I
O
300 mA
- 0.0025 0.0065 %/mA
V
O
/V
O
relative output voltage
variation
V
I
=V
O(nom)
+1V - - 2 %
