STP1612PW05 STMicroelectronics, STP1612PW05 Datasheet - Page 27

• Manufacturer Part Number: STP1612PW05
• Description: 16-channel LED driver with 16-bit PWM, 8-bit gain and full LED error detection
• Manufacturer: STMicroelectronics

Specifications of STP1612PW05

• Supply Voltage: 3.3 V or 5 V
• Max Clock Frequency: 30 MHz

STP1612PW05
17
17.1
Application information
LED supply voltage (VLED)
The choice of the LED supply voltage (VLED) must be carried out considering several
parameters:
●
●
●
●
Therefore the minimum LED supply voltage can be calculated as:
The LED supply voltage should be higher than V
involved parameters) but not too high in order to keep low the power dissipation:
where D
In particular the power dissipation should be kept below the maximum power dissipation,
defined as:
To summarize, the choice of the proper power supply must be a trade-off between the
correct value that assures the desired LED current and low power dissipation.
In RGB application, there can be a significant variability of the LEDs forward voltage (e.g.
red LEDs have a lower forward voltage compared to green and blue ones).
In this case the supply voltage must be chosen high enough to correctly switch on the LEDs
with the highest forward voltage (green or blue). However this supply voltage is higher than
the voltage required by red LEDs. Thus, the excess of voltage in the lines with red LEDs
drops on the current generators, bringing to an increase of the power dissipation and loss of
efficiency.
Moreover the extra-voltage across the red LEDs driving generators could cause an
erroneous shorted LED condition detection.
The voltage drop across current generators (V
the desired current (see
The maximum LED forward voltage (V
The maximum power that can be dissipated by the package under the application
ambient conditions
The accuracy of the supply voltage itself (VLED can vary in a range and the minimum
value should be considered)
i
is the duty cycle of the channel i.
Figure 14
Doc ID 15819 Rev 5
P
D
=
V
LED
V
DD
P
,
, D
min
and
⋅
max
I
DD
=
F,max
Figure
=
V
+
O
∑
(
16
i
,
T
=
typ
)
1
j
LED,min
θ
−
V
ja
+
O
T
O
15)
V
i ,
a
), which must be enough to guarantee
, F
⋅
)
I
max
CHi
(to consider any fluctuation of the
⋅
D
i
Application information
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