MAX1578-MAX1579 Datasheet, PDF (3/13 Pages) Maxim Integrated Products – Complete Bias and White LED Power Supplies for Small TFT Displays

Complete Bias and White LED Power Supplies
for Small TFT Displays
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
NEG Output Voltage
NEG Discharge Switch Resistance
LOGIC INPUT (ONBIAS)
Logic Input Low Voltage
Logic Input High Voltage
Input Current
LED BACKLIGHTING
Efficiency
CONDITIONS
I_LOAD = 0 to -100µA
V_ONBIAS = 0V
T_A = +25°C
T_A = +85°C
LOAD = 6 LEDs in series at 20mA
MIN
-10.2
TYP
-9.8
1.5
MAX
-9.3
3
UNITS
V
kΩ
0.72
V
1.6
V
0.01
1
µA
1
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
OUT Input Bias Current
V_OUT = V_IN, V_CTRL = 0
T_A = +25°C
T_A = +85°C
0.01
1
µA
0.1
ERROR AMPLIFIER
CTRL to CS Regulation
CS Input Bias Current
V_CTRL = 1.5V, V_IN = 2.7V to
5.5V
V_CS = V_CTRL / 5
T_A = +25°C
T_A = -40°C to +85°C
T_A = +25°C
T_A = +85°C
MAX1578
0.295 0.300 0.305
V
0.292 0.300 0.308
0.01
1
µA
0.03
250 500 780
CTRL Input Resistance
CTRL Dual Mode™ Threshold
V_CTRL < 1.0V
5mV hysteresis
MAX1579 ^{TA = +25°C}
250
500
780
kΩ
T_A = +85°C
185
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
CS Maximum Brightness Clamp
Voltage
CS Maximum Brightness Voltage
at CTRL
OSCILLATOR
MAX1578, V_CTRL = 3V
MAX1579, V_CTRL = 3V, T_A = +25°C
MAX1578
MAX1579
310 327 345
mV
322 340 358
1.635
V
1.70
Operating Frequency
Minimum Duty Cycle
f_BOOST
PWM mode
Pulse skipping
0.8
1.0
1.2
MHz
12
%
0
Maximum Duty Cycle
CTRL = IN, CS = GND
92
95
%
Dual Mode is a trademark of Maxim Integrated Products, Inc.
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