SC900841JVKR2 Freescale Semiconductor, SC900841JVKR2 Datasheet - Page 87

• Manufacturer Part Number: SC900841JVKR2
• Description: IC POWER MGT 338-MAPBGA
• Manufacturer: Freescale Semiconductor

Specifications of SC900841JVKR2

• 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

Table 43. VBKLT Under-voltage Comparator Status
Under-voltage Detection
comparator that serves as an output ready signal along with
the absence of faults. When VBKLT is turned on,
VBKLTFAULT is asserted, the under-voltage comparator is
turned on, and VOBKLT starts ramping up. When VBKLT
reaches a steady state, VBKLTFAULT is de-asserted, to
indicate the VBKLT output readiness to start PWMing the
LED sinks.
voltage comparator is turned off, since the output voltage will
not be regulated and is moving, depending on the LED
current level and forward voltage drop. If VBKLT is only
supplying the camera scene illumination, the under-voltage
comparator can stay on, as it is set as a fixed output voltage
of 22 V.
undervoltage threshold, an undervoltage condition is
detected, VBKLTFAULT is asserted. If the output voltage
rises above the under-voltage threshold plus hysteresis, then
the VBKLTFAULT signal is cleared, assuming no other faults
are occurring.
Analog Integrated Circuit Device Data
Freescale Semiconductor
Table 42. Backlight and Camera Scene LED Enable Bits Control
MLEDxEN
VBKLT features an output under-voltage detection
If VBKLT is supplying the backlight LEDs, the under-
During operation if the output voltage decreased below the
0
0
0
0
0
0
0
1
1
1
1
1
1
0
0
1
1
SLEDEN
0
0
1
1
1
1
1
0
0
0
0
0
1
0
1
0
1
0
1
0
0
0
1
1
0
0
0
1
1
Turns OFF After VBKLT Ready
Turns OFF After VBKLT Ready
x
Stays On After VBKLT Ready
Under-voltage Comparator
OFF
1
1
0
1
1
0
1
0
1
1
0
1
x
1
0
1
0
1
x
x
x
x
x
x
x
x
Invalid: PWM mode can't be set at the same time than Backlight for
Over-voltage Protection
comparator that senses the output voltage through an
internal resistor divider connected at the FBBKLT pin. It
compares the output voltage to an internal reference and
shuts down the regulator, in the case an excessive voltage
occurs, due to an open LED or other reason, and asserts the
VBKLTFAULT flag. The over-voltage threshold is fixed at
24 V, typical. The output is re-enabled, the VBKLTFAULT is
cleared (assuming no other faults are occurring), and normal
operation is resumed when the voltage drops below the over-
voltage threshold, minus hysteresis.
turned off.
Zener diode from the output to ground. The Zener breakdown
must be at least 3.0 V higher than the output voltage setting.
Over-current Protection
switch MOSFET current. The over-current threshold value is
set higher than the worst peak inductor current value. If an
over-current is detected, the switch MOSFET turns off, the
VBKLTFAULT flag is asserted, and the regulator goes into a
cycle by cycle current limiting until the fault is serviced. If the
output current falls below the over-current threshold, normal
operation is regained, and the VBKLTFAULT is cleared
(assuming no other faults are occurring).
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
VBKLT features an output over-voltage protection
Any current sinks being supplied from VBKLT are also
The output voltage can also be clamped by connecting a
VBKLT also limits the peak inductor current by sensing the
S1-3 Backlight - BKLT1
S1-3 Backlight - BKLT1
S1-3 Backlight - BKLT1
S1-2 Backlight - BKLT1
S1-2 Backlight - BKLT1
S3 Backilight - BKLT2
S3 Backlight - BKLT2
S1-3 PWM - BKLT1
S1-3 PWM - BKLT1
S1-3 PWM - BKLT1
S1-2 PWM - BKLT1
S1-2 PWM - BKLT1
S3 PWM - BKLT2
S3 PWM - BKLT2
OFF
OFF
strings 1-3
FUNCTIONAL DEVICE OPERATION
Backlight - BKLT1
Backlight - BKLT2
Backlight - BKLT1
Backlight - BKLT2
Backlight - BKLT1
Backlight - BKLT2
Camera Scene
Camera Scene
POWER SUPPLIES
OFF
OFF
OFF
OFF
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