BL0200C Datasheet, PDF (14/26 Pages) Sanken electric – High Efficiency

BL0200 Series
8.6 Error Signal Output Function (BL0200C)
When the protection function is active, the internal
switch becomes OFF. The drain of this internal switch is
connected to ER pin.
In case the error signal is received by external
microcomputer, the pull-up resistor, R40, and the
protection resistor of ER pin, R39, are connected as
shown in Figure 8-12. When the protection function is
active, ER_OUT becomes REG pin voltage from 0 V.
The resistances of R39 and R40 are about 10 kΩ.
REG
1
ER
Auto restart
17
protection
GND
7
R40
R39
C12
ER_OUT
Auto Restart 1:
As shown in Figure 8-13, the IC repeats an
intermitted oscillation operation, after the detection of
any one of abnormal states 1 to 5 in Table 8-2. This
intermitted oscillation is determined by tARS1 or
tARS2, and tAROFF1.
The tARS1 is an oscillation time in the first
intermitted oscillation cycle, TAR1. The tARS2 is an
oscillation time in the second and subsequent
intermitted oscillation cycle, TAR2. The tAROFF1 is
a non-oscillation time in all intermitted oscillation
cycle.
In case PWM dimming frequency is low and the
on-duty is small, the startup operation, the restart
operation from on-duty = 0 % and the restart operation
from intermitted oscillation operation need a long time.
Thus the value of tARS1 and tARS2 depend on
frequency and on-duty of the PWM dimming signal,
as shown in Figure 8-15 and Figure 8-16 for BL020×C,
Figure 8-17 and Figure 8-18 for BL0202B.
Figure 8-12 ER pin peripheral circuit
Table 8-3 shows the Auto Restart 1 oscillation time,
tARS1, tARS2, and the Auto Restart 1 non-oscillation
time, tAROFF1, at on-duty = 100 %.
8.7 Protection Function
As shown in Table 8-2, the IC performs protection
operations according to kind of abnormal state. In all
protection functions, when the fault condition is removed,
the IC returns to normal operation automatically. The
intermitted oscillation operation reduces stress on the
power MOSFET, the secondary rectifier diode, and so
forth.
Table 8-3 Oscillation time and non-oscillation time
(at on-duty = 100 %)
BL0200C
BL0202C
BL0202B
Oscillation
time, t_ARS1
31 ms
61.4 ms
Oscillation
time, t_ARS2
20.5 ms
41.0 ms
non-oscillation
time, t_AROFF1
About 635 ms
About 1.3 s
Table 8-2 Relationship between a kind of abnormal state
and protection operations
Abnormal States
1 Overcurrent of boost circuit (OCP)
Protection
Operations
2 Overcurrent of LED output (LED_OCP)
3 Overvoltage of LED_OUT(+) (OVP)
4
Short mode between LED_OUT(−) and
GND
5
Short mode of LED current detection
resistor (R_SEN_Short)
6 Short mode of both ends of LED output
7
Open mode of LED current detection
resistor (R_SEN_Open)
8
Overtemperature of junction of IC
(TSD)
Auto
Restart 1
Auto
Restart 2
Auto
Restart 3
Auto Restart 2:
As shown in Figure 8-14, the IC stops the switching
operation immediately after the detection of abnormal
states 6 or 7 in Table 8-2, and repeats an intermitted
oscillation operation. In the intermitted oscillation cycle,
the t_ARSW is an oscillation time, the t_AROFF1 is a
non-oscillation time.
The value of t_ARSW is a few microseconds. The value
of t_ARS2 is derived from Figure 8-18, and t_AROFF2 is
calculated as follows:
t _{AROFF 2}  t _ARS2  t _ARSW  t _AROFF1
(8-3)
In case the on-duty is 100%, the value of t_AROFF2
becomes as follows:
L0200C、BL0202C：
t_AROFF2 ≒ 20.5 + 635 = 655.5 (ms)
BL0202B：
t_AROFF2 ≒ 0.041 + 1.3 = 1.341 (s)
BL0200-DS Rev.2.1
SANKEN ELECTRIC CO.,LTD.
14
Feb. 25, 2014