IR2159 International Rectifier, IR2159 Datasheet - Page 17

• Manufacturer Part Number: IR2159
• Description: IC BALLAST CONTROL DIM 16-DIP
• Manufacturer: International Rectifier
• Type: Ballast Controllerr

Specifications of IR2159

• Frequency: 25 ~ 95 kHz
• Current - Supply: 10mA
• Voltage - Supply: 12.5 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
• Current - Output: -

www.irf.com
Brown-out Protection
In addition to the voltage on VCC being above
the start-up threshold, pin VDC must also be
above 5.1V for HO and LO to begin oscillating. A
voltage divider (R3,RVDC) from the rectified AC
line connected to pin VDC measures the rectified
AC line input voltage to the ballast and programs
the turn-on and turn-off line voltages. A filter
capacitor (CVDC) is also connected to pin VDC
that must be chosen such that the ripple is low
enough and the lower turn-off threshold of 3V is
not crossed during normal line conditions. This
detection is necessary due to the possibility of
the lamp extinguishing during low-line conditions
before the IC is properly reset. Should a brown-
out occur, the DC bus can drop to a level below
the minimum required for the tank circuit to
maintain the necessary lamp voltage. This
detection will insure a clean turn-off before the
DC bus drops too low and properly resets the
IC to the preheat mode when the line returns.
Preheat (PH)
The IR2159 enters preheat mode when VCC
exceeds the UVLO+ threshold and VDC exceeds
5.1V. HO and LO begin to oscillate at the
maximum operating frequency with 50% duty
cycle and at the internally set dead-time of 2us.
Pin CPH is disconnected from COM and an
internal 1uA current source (Figure 7) charges
the external timing capacitor on CPH linearly.
An internal 1uA current source slowly discharges
the external capacitor on pin VCO and the voltage
on pin VCO begins to decrease. This decreases
the frequency, which, for operating frequencies
above resonance, increases the load current.
When the peak voltage measured on pin CS,
produced by a portion of the load current flowing
through an external sense resistor (RCS), exceeds
the voltage level on pin IPH, a 60uA internal
current source is connected to pin VCO and the
capacitor charges (Figure 8). This forces the
frequency to increase and the load current to
decrease. When the voltage on pin CS decreases
below IPH, the 60uA current source is
disconnected and the frequency decreases again.
V
V
BUS
BUS
(+)
(-)
C
C
R
R
VCO
CPH
IPH
FMIN
FMIN
CPH
Figure 7, IR2159 preheat circuitry.
VCO
IPH
IR2159/IR21591
2
3
7
8
1/R
60uA
1uA
I
FMIN
1uA
FMIN
5.1V
7.6V
LOGIC
VCO
PH
Half
Bridge
Driver
IR2159
16
15
11
10
12
HO
VS
LO
CS
COM
Q2
Q2
RCS
Load
Return
Half
Bridge
Output
I
( S )
LOAD
17