Typical operating characteristics, Electrical characteristics (continued) – Rainbow Electronics MAX1579 User Manual
Page 4
MAX1578/MAX1579
Complete Bias and White LED Power Supplies
for Small TFT Displays
4
_______________________________________________________________________________________
Note 1:
All devices are 100% production tested at T
A
= +25
°C. Limits over the operating temperature range are guaranteed by design.
Note 2:
V
D1
is the forward-voltage drop of diode D1 in Figure 3.
Note 3:
Time from CTRL going below the Dual-Mode threshold to IC shutdown.
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 3, V
IN
= 3V, CTRL = ONBIAS = IN, T
A
= -40
°C to +85°C, typical values are at T
A
= +25
°C, unless otherwise noted. Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
N-CHANNEL SWITCH
LX On-Resistance
I
LX
= 190mA
0.82
1.5
Ω
T
A
= +25°C
0.01
5
LX Leakage Current
V
LX
= 28V, CTRL = GND
T
A
= +85°C
1
µA
LX Current Limit
Duty cycle = 90%
500
700
900
mA
Typical Operating Characteristics
(Circuit of Figure 3, V
IN
= 3.6V, I
LED
= 20mA, 4 LEDs, CTRL = IN, T
A
= +25
°C, unless otherwise noted.)
50
55
60
65
70
75
80
85
90
0
5
10
15
20
25
LED EFFICIENCY vs. I
LED
MAX1578toc01
LED CURRENT (mA)
EFFICIENCY (%)
2 LEDs
4 LEDs
6 LEDs
8 LEDs
50
55
60
65
70
75
80
85
90
2.5
3.0
3.5
4.0
4.5
5.0
5.5
LED EFFICIENCY vs. V
IN
MAX1578toc02
INPUT VOLTAGE (V)
EFFICIENCY (%)
I
LED
= 2mA
I
LED
= 10mA
I
LED
= 20mA
0
10
5
20
15
25
30
-40
85
LED CURRENT vs. TEMPERATURE
MAX1578toc03
TEMPERATURE (
°C)
I
LED
(mA)
10
-15
35
60
MAX1579
R
CS
= 13
Ω
MAX1578
R
CS
= 22
Ω
0
5
15
10
20
25
0
1.0
0.5
1.5
2.0
2.5
LED CURRENT vs. V
CTRL
MAX1578toc04
CTRL VOLTAGE (V)
I
LED
(mA)