IR21571 International Rectifier, IR21571 Datasheet - Page 14
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IR21571
Manufacturer Part Number
IR21571
Description
IC BALLAST CONTROL 16-DIP
Manufacturer
International Rectifier
Type
Ballast Controllerr
Datasheet
1.IR21571PBF.pdf
(18 pages)
Specifications of IR21571
Frequency
45.5 ~ 50.5 kHz
Current - Supply
5.5mA
Current - Output
500mA
Voltage - Supply
11.4 V ~ 15.6 V
Operating Temperature
-40°C ~ 125°C
Package / Case
16-DIP (0.300", 7.62mm)
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Other names
*IR21571
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
IR21571
Manufacturer:
IR
Quantity:
20 000
Part Number:
IR21571S
Manufacturer:
IR
Quantity:
20 000
Company:
Part Number:
IR21571STR
Manufacturer:
IR
Quantity:
191
Part Number:
IR21571STRPBF
Manufacturer:
IR
Quantity:
20 000
Thus, for a lamp removal and replacement, the ballast
automatically restarts the lamp in the proper manner,
maximizing lamp life and minimizing stress on the
power MOSFETs or IGBTs. The SD lead contains an
internal 7.5V zener diode clamp, thereby reducing
the number of external components required.
The third lead used for protection is the CS lead,
which is normally connected to a resistor in the source
of the lower power MOSFET, as shown in Figure 14.
The CS lead is used to sense fault conditions such
as failure of a lamp to strike, over-current during
normal operation, hard switching, no load, and
operation below resonance. If any one of these
conditions is sensed, the fault latch is set, the oscillator
is disabled, the gate driver outputs go low, and the
chip is put into the micropower mode. The CS lead
performs its sensing functions on a cycle-by-cycle
basis in order to maximize ballast reliability.
switching
programmable, positive-going CS+ threshold is
IR21571 (S) & (PbF)
14
For the over-current, failure-to-strike, and hard
R
VDC
CPH
RPH
RUN
OC
OC
Half-Bridge Current Sensing and
RT
CT
DT
Figure 14: Half-bridge current sensing circuit
1
2
3
4
5
6
7
8
fault
connection (shaded area)
16
15
14
13
12
11
10
9
VCC
COM
HO
CS
SD
VS
VB
LO
Protection
conditions,
C
D
R
BOOT
BOOT
GHS
AC line
rectifie
R
GLS
d
R
C
SUPPLY
R3
VCC
D1
V
BUS
+V
BUS
return
Q1
Q2
R
an
CS
externally
C
D2
SNUBBER
1
/
2
output
Bridge
enabled at the end of the preheat time. The level of
this positive-going threshold is determined by the
value of the resistor ROC. The value of the resistor
ROC is determined by the following formula:
For the under-current and under-resonance
conditions, there is a negative-going CS- threshold
of 0.2V which is enabled at the onset of the run mode.
The sensing of this CS- threshold is synchronized
with the falling edge of the LO output.
Figures 15, 16 and 17 are oscillographs of fault
conditions. Figure 15 shows a failure of the lamp to
strike, Figure 16 shows a hard switching condition
and Figure 17 shows an under-current condition.
R
V
OC
CS
Figure 15: Lamp failure to strike
+ =
=
50E -6 - R
50E - 6
V
CS
+
or
OC
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