Datasheet

ADP160/ADP161/ADP162/ADP163 Data Sheet
Rev. H | Page 18 of 24
140
120
100
80
60
40
20
0
0.3 4.84.33.83.32.82.31.81.30.8
V
IN
– V
OUT
(V)
JUNCTION TEMPERATURE, T
J
(°C)
I
LOAD
= 1mA
I
LOAD
= 10mA
I
LOAD
= 50mA
I
LOAD
= 100mA
I
LOAD
= 150mA
I
LOAD
= 200mA
MAXIMUM JUNCTION TEMPERATURE
08628-046
Figure 48. 100 mm
2
of PCB Copper, TSOT, T
A
= 50°C
140
120
100
80
60
40
20
0
0.3 4.84.33.83.32.82.31.81.30.8
V
IN
– V
OUT
(V)
JUNCTION TEMPERATURE, T
J
(°C)
I
LOAD
= 1mA
I
LOAD
= 10mA
I
LOAD
= 50mA
I
LOAD
= 100mA
I
LOAD
= 150mA
I
LOAD
= 200mA
MAXIMUM JUNCTION TEMPERATURE
08628-047
Figure 49. WLCSP, T
A
= 85°C
140
120
100
80
60
40
20
0
0.3 4.8
4.33.83.32.82.31.81.30.8
V
IN
– V
OUT
(V)
JUNCTION TEMPERATURE, T
J
(°C)
I
LOAD
= 1mA
I
LOAD
= 10mA
I
LOAD
= 50mA
I
LOAD
= 100mA
I
LOAD
= 150mA
I
LOAD
= 200mA
MAXIMUM JUNCTION TEMPERATURE
08628-048
Figure 50. TSOT, T
A
= 85°C
PCB LAYOUT CONSIDERATIONS
Heat dissipation from the package can be improved by increasing
the amount of copper attached to the pins of the ADP16x. However,
as listed in Table 8, a point of diminishing returns is reached
eventually, beyond which an increase in the copper size does
not yield significant heat dissipation benefits.
Place the input capacitor as close as possible to the VIN and
GND pins. Place the output capacitor as close as possible to the
VOUT and GND pins. Use of 0402 or 0603 size capacitors and
resistors achieves the smallest possible footprint solution on
boards where area is limited.
LIGHT SENSITIVITY OF WLCSPs
The WLCSP package option is essentially a silicon die with
additional post fabrication dielectric and metal processing
designed to contact solder bumps on the active side of the chip.
With this package type, the die is exposed to ambient light and
is subject to photoelectric effects. Light sensitivity analysis of
a WLCSP mounted on standard PCB material reveals that
performance may be impacted when the package is illuminated
directly by high intensity light. No degradation in electrical
performance is observed due to illumination by low intensity
(0.1 mW/cm
2
) ambient light. Direct sunlight can have inten-
sities of 50 mW/cm
2
, office ambient light can be as low as
0.1 mW/cm
2
.
When the WLCSP is assembled on the board with the bump
side of the die facing the PCB, reflected light from the PCB
surface is incident on active silicon circuit areas and results
in the increased leakage currents. No performance degrada-
tion occurs due to illumination of the backside (substrate) of
the WLCSP.
All WLCSPs are particularly sensitive to incident light with
wavelengths in the near infrared range (NIR, 700 nm to 1000 nm).
Photons in this waveband have a longer wavelength and lower
energy than photons in the visible (400 nm to 700 nm) and near
ultraviolet (NUV, 200 nm to 400 nm) bands; therefore, they can
penetrate more deeply into the active silicon.
Incident light with wavelengths greater than 1100 nm has
no photoelectric effect on silicon devices because silicon is
transparent to wavelengths in this range.
The spectral content of conventional light sources varies
considerably. Sunlight has a broad spectral range, with peak
intensity in the visible band that falls off in the NUV and NIR
bands; fluorescent lamps have significant peaks in the visible
but not the NUV or NIR bands. Tungsten lighting has a broad
peak in the longer visible wavelengths with a significant tail in
the NIR.
Efforts have been made at a product level to reduce the effect of
ambient light; the under bump metal (UBM) has been designed
to shield the sensitive circuit areas on the active side (bump
side) of the die. However, if an application encounters any light
sensitivity with the WLCSP, shielding the bump side of the
WLCSP package with opaque material should eliminate this
effect. Shielding can be accomplished using materials such as
silica-filled liquid epoxies like those used in flip-chip underfill
techniques.