MP1015 ETC1 [List of Unclassifed Manufacturers], MP1015 Datasheet - Page 5

• Manufacturer Part Number: MP1015
• Description: Full System Precision CCFL Driver
• Manufacturer: ETC1 [List of Unclassifed Manufacturers]

Feature Description (continued)
Fault Timer: The timing for the fault timer will
depend on the sourcing current, as described
above, and the capacitor on the FT pin. The user
can program the time for the voltage to rise before
the chip detects a “real“ fault.
triggered, then the internal drive voltage (V
collapse from 6.2V to 0V. The reference voltage will
stay high at 5.0V.
Lamp Startup
The strike voltage of the lamp will always be
guaranteed at any temperature because the
MP1015 uses a resonant topology for switching the
outputs. The device will continue to switch at the
resonant frequency of the tank until the strike
voltage is achieved. This eliminates the need for
external ramp timing circuits to ensure startup.
Chip Enable
The chip has an on / off function, which is
controlled by the En pin (#5). The enable signal
goes directly to a Schmitt trigger. The chip will turn
ON with an En = High and OFF with an En = Low.
Application Information
Pin 19 (ISFB) : Rsfb, Csfb , Risb and Cisb
(Secondary Short Protection)
The Rsfb and Csfb combination is used for
feedback to the IS pin to detect excessive
secondary current. These resistors have to be +/-
5% tolerance components. The value for Rsfb is
approximately 1.7KΩ and Csfb is approximately
82nF. This will ensure that the voltage at the ISFB
pin is typically 1.0V during steady state operation.
The maximum value for Csfb is 93nF to ensure that
the chip will meet the UL1950 specification. Risb
and Cisb components are used as a high pass
filter.
Pin 18 (VLFB): Cs1, Cs2 and Rs
(Open Lamp protection)
The regulated open lamp voltage is proportional to
the Cs1 and Cs2 ratio. Cs1 has to be rated at 3KV
and is typically between 5 to 22pF. The value of
Cs1 is typically 15pF and is chosen for a specified
maximum frequency. The value of Cs2 is set by the
MP1015 Rev 2.7_03/25/03
Monolithic Power Systems
When a fault is
Drv
www.monolithicpower.com
) will
Customer to achieve the required open lamp
voltage detection value, typically 4nF.
The value of Rs is typically 300KΩ (not critical).
Pin 17 (FT): Cft
The Cft cap is used to set the fault timer. This
capacitor will determine when the chip will reach
the fault threshold value. The user can choose the
cap value to set the time out value.
Open Lamp Time
For a Cft= 820nF, then the time out for open lamp
will be 0.98 sec.
Secondary Short Turn Off time
Because the sourcing current for a secondary short
is approx. 120µA, then the off time when a resistive
short occurs across the lamp will be approx 100
times faster than the open lamp time.
To reduce the turn off time even further, then by
modifying the connection at the FT node to:
For a Cap=10nF, then the time out for secondary
short will be 0.11ms. The turn off time for the
secondary short will be reduced by an additional
100 times.
Note: The open lamp time will remain the same
value as defined by C
Pin 16 (Comp): Ccomp
This cap is the system compensation cap that
connects between comp and AGnd.
2.2nF cap is recommended. This cap should be
X7R ceramic with a voltage rating sufficient for 5V
biasing. The value of Ccomp affects the soft-on rise
time
C
Figure 3: Turn Off Time Adjustment
Cs2=Cs1 * V(max)rms/ 3.5Vrms)
ft (nF) =
and
Cft
Precision CCFL Driver
T
(open lamp) (1µA)/ 1.2 V
100K
soft-off
ft
.
10nf
Full System
MP1015
FT
fall
A 1.5nf or
time.
5