Electrical characteristics (continued) – Rainbow Electronics MAX1579 User Manual
Page 3
MAX1578/MAX1579
Complete Bias and White LED Power Supplies
for Small TFT Displays
_______________________________________________________________________________________
3
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
NEG Output Voltage
I
LOAD
= 0 to -100µA
-10.2
-9.8
-9.3
V
N E G D i schar g e S w i tch Resi stance
V
ONBIAS
= 0V
1.5
3
k
Ω
LOGIC INPUT (ONBIAS)
Logic Input Low Voltage
0.72
V
Logic Input High Voltage
1.6
V
T
A
= +25°C
0.01
1
Input Current
T
A
= +85°C
1
µA
LED BACKLIGHTING
Efficiency
LOAD = 6 LEDs in series at 20mA
84
%
OUT Voltage Range
(Note 2)
(V
IN
-
V
D1
)
32
V
Overvoltage-Lockout (OVLO)
Threshold
V
OUT
rising, 2V hysteresis
32
34
36
V
V
OUT
= 32V, V
CTRL
> 0.24V
10
20
32
T
A
= +25°C
0.01
1
OUT Input Bias Current
V
OUT
= V
IN
, V
CTRL
= 0
T
A
= +85°C
0.1
µA
ERROR AMPLIFIER
T
A
= +25°C
0.295
0.300
0.305
CTRL to CS Regulation
V
CTRL
= 1.5V, V
IN
= 2.7V to
5.5V
T
A
= -40°C to +85°C
0.292
0.300
0.308
V
T
A
= +25°C
0.01
1
CS Input Bias Current
V
CS
= V
CTRL
/ 5
T
A
= +85°C
0.03
µA
MAX1578
250
500
780
T
A
= +25°C
250
500
780
CTRL Input Resistance
V
CTRL
< 1.0V
MAX1579
T
A
= +85°C
185
k
Ω
CTRL Dual Mode
™ Threshold
5mV hysteresis
100
170
240
mV
CTRL Shutdown Delay
(Note 3)
6.5
8.2
10.5
ms
CS to COMP Transconductance
V
COMP
= 1.0V
32
60
90
µS
CS Regulation Derating Function
Start Temperature
V
CTRL
= 3V, MAX1579 only
+42
°C
CS Regulation Derating Function
Slope
V
CTRL
= 3V, T
A
= +65°C, MAX1579 only
-6
mV/°C
MAX1578, V
CTRL
= 3V
310
327
345
CS Maximum Brightness Clamp
Voltage
MAX1579, V
CTRL
= 3V, T
A
= +25°C
322
340
358
mV
MAX1578
1.635
CS Maximum Brightness Voltage
at CTRL
MAX1579
1.70
V
OSCILLATOR
Operating Frequency
f
BOOST
0.8
1.0
1.2
MHz
PWM mode
12
Minimum Duty Cycle
Pulse skipping
0
%
Maximum Duty Cycle
CTRL = IN, CS = GND
92
95
%
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)
Dual Mode is a trademark of Maxim Integrated Products, Inc.