SC900841JVK Freescale Semiconductor, SC900841JVK Datasheet - Page 86

• Manufacturer Part Number: SC900841JVK
• Description: IC POWER MGT 338-MAPBGA
• Manufacturer: Freescale Semiconductor

Specifications of SC900841JVK

• Applications: PC's, PDA's
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 338-TBGA
• Input Voltage: 2.8 V to 4.4 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Voltage - Supply: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Operation
another load, however the backlight LEDs can be operated
without VBKLT.
VBKLT uses the lowest voltage of WLED1, WLED2, WLED3,
or LEDSCN (if used for backlight support and/or S4ADAPT
bit in register FSLVBKLTADAPT is set) as its reference
voltage for output voltage regulation. This method assures
the string with the highest drop (lowest voltage) has enough
voltage headroom to operate, and the minimum output
voltage (maximum forward voltage drop across LED strings +
voltage headroom necessary to operate the current sinks) is
set at the minimum value necessary to drive all LED strings,
which reduces power dissipation. If the 4th string is used for
outputs by providing a pull-up to a supply, such as 3.3 V.
These PWM outputs can be used to drive an "Integrated
Display" with local power supply. In this case, and in the
event camera scene illumination is not needed either, then
VBKLT is not used and the current sinks are enabled by the
PWMEN signal. This signal only enables the current sinks
and not VBKLT
voltage drop of less than the maximum battery voltage.
isolation FET (the output is directly connected to the input
through the inductor and the external diode). VBKLT however
limits the LED leakage current in the off state through the
internal current sinks.
an applications work-around. Reference the Freescale's
86
900841
Table 41. VBKLT Reference Selection
FUNCTIONAL DEVICE OPERATION
POWER SUPPLIES
Table 42. Backlight and Camera Scene LED Enable Bits Control
VBKLT is not independent and cannot be operated with
When supplying only the LCD backlight or both loads,
The LED current sinks, WLED1-3, can be used as PWM
VBKLT cannot drive LED(s) with a total minimum forward
VBKLT cannot be discharged due to the lack of an
VBKLT can support higher number of LEDs in series, with
PWMEN
MLED1EN
0
0
0
0
0
0
x
1
x
x
MLEDxEN
0
0
MLED2EN
0
0
0
0
1
x
x
x
TWOPTWO
0
x
MLED3EN
SLEDEN
0
0
0
0
1
x
x
x
0
1
MLED4EN
MLED4EN
0
x
0
0
0
1
1
x
x
x
VBKLT
camera scene illumination application, then it does not
control the output voltage VBKLT.
the output voltage of VBKLT is fixed to 22 V, and uses a fixed
reference voltage.
900841 can support an independent zone backlighting
option, where strings 1 and 2 support one display backlight,
and strings 3 and 4 (Camera scene) support another display.
Both string groups are completely independent in terms of
frequency and duty cycle control. They are both still supplied
from the VBKLT rail.
MLED1EN, MLED2EN, MLED3EN, MLED4EN, and
SLEDEN bits as shown in
Evaluation Board KITINTMIDPMMEVBE schematics or
discuss with your Freescale representative for more details.
VBKLT Enable Control
depending on the display type used and the loads being
supplied.
unless the camera scene enable bit (SLEDEN) is asserted.
Also, in order for the 4th string to have the ability to turn on
VBKLT, SLEDEN has to be asserted.
SLEDEN has to also be asserted. This holds true in all of the
cases in
bits, the status of VBKLT, and the application mode
supported. An “x” in the MLEDxEN column refers to strings 1,
2, and 3.
OFF
ON
SLEDEN
When supplying only the camera scene illumination string,
By setting the TWOPTWO bit in the FSLVBKLTCNTL, the
This reference voltage selection is controlled by the
Table 42
Note that the 4th string cannot be operated for backlighting
In summary, in order for MLED4EN to have any effect,
Table 42
0
1
1
0
1
x
x
x
Table
outlines the relation between the different enable
outlines different cases for VBKLT operation,
42.
String 1-3
S4ADAPT
OFF
OFF
Analog Integrated Circuit Device Data
0
0
1
x
x
x
x
x
Table
41.
Freescale Semiconductor
VBKLT Voltage
Camera Scene
Reference
Adaptive
Adaptive
Adaptive
Adaptive
Adaptive
String 4
Invalid
Fixed
OFF
OFF