Rainbow Electronics MAX1579 User Manual
Page 2
MAX1578/MAX1579
Complete Bias and White LED Power Supplies
for Small TFT Displays
2
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ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(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)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
IN, CS, C1N, C2N, MAIN, ONBIAS, V
DD
to GND.....-0.3V to +6V
CTRL to GND..................-0.3V to the lesser of +6V or (V
IN
+ 2V)
LX, OUT to GND .....................................................-0.3V to +37V
COMP to GND .............................................-0.3V to (V
IN
+ 0.3V)
CU1 to MAIN ............................................................-0.3V to +6V
CU2 to CU1 ..............................................................-0.3V to +6V
CU3 to CU2 ..............................................................-0.3V to +6V
CU3 to POS ............................................................-0.3V to +18V
CU3 to GND ...........................................................-0.3V to +18V
POS to GND ...........................................................-0.3V to +18V
CD1 to MAIN ..........................................................+0.3V to -12V
CD1 to GND .............................................................+0.3V to -6V
CD2 to CD1 ..............................................................+0.3V to -6V
NEG to CD2..............................................................+0.3V to -6V
NEG, CD2 to GND..................................................+0.3V to -12V
C1P, C2P to GND ...........................................-0.3V to (V
IN
+ 6V)
PMP, PMPB to GND ................................-0.3V to (V
MAIN
+ 0.3V)
GND to PGND .......................................................-0.3V to +0.3V
I
LX
...................................................................................1.0A
RMS
Continuous Power Dissipation (T
A
= +70
°C)
24-Pin 4mm x 4mm Thin QFN
(derate 20.8mW/
°C above +70°C) .............................1667mW
Short-Circuit Duration (MAIN, POS, NEG)..................Continuous
Operating Temperature Range ...........................-40
°C to +85°C
Junction Temperature ......................................................+150
°C
Storage Temperature Range .............................-65
°C to +150°C
Lead Temperature (soldering, 10s) ................................ +300
°C
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
IN Operating Supply Range
2.7
5.5
V
IN Undervoltage-Lockout (UVLO)
Threshold
Rising edge, 30mV hysteresis
2.1
2.35
2.6
V
IN Quiescent Current
Switching
3
5
mA
T
A
= +25°C
0.4
1
IN Shutdown Current
V
CTRL
= V
ONBIAS
= 0V
T
A
= +85°C
1
µA
Thermal Shutdown
Rising temperature, 20°C hysteresis (typ)
+160
°C
MAIN CHARGE PUMP WITH LINEAR REGULATOR
Main Pump Efficiency
I
LOAD
= 25mA, V
IN
= 3.9V
83
%
V
IN
≥ 3.8V in 1.5x mode
9
20
V
DD
Charge-Pump Open-Loop
Output Impedance
V
IN
≥ 3.0V in 2.0x mode
7.5
20
Ω
Operating Frequency
200
250
300
kHz
V
DD
Output Voltage
Charge-pump pause threshold
5.2
5.5
5.7
V
V
IN
Fal l i ng S w i tchover to 2.0x M od e
3.75
3.85
3.95
V
V
IN
Ri si ng S w i tchover to 1.5x M od e
3.8
3.9
4.0
V
Quiescent Current
(Charge Pumps Only)
V
CTRL
= 0V, ONBIAS = IN
0.87
1.30
mA
V
MAIN
Regulation Voltage
0.1mA < I
LOAD
< 25mA
4.9
5.0
5.1
V
Discharge Switch Resistance
at V
MAIN
V
ONBIAS
= 0V
1
3
k
Ω
POS, NEG CHARGE PUMPS
Operating Frequency
12.0
15.6
19.5
kHz
Duty Cycle
50
%
POS Pump Efficiency
I
LOAD
= 100µA
97
%
POS Output Voltage
I
LOAD
= 0 to 100µA
13.9
14.7
15.3
V
P OS D i schar g e S w i tch Resi stance
V
ONBIAS
= 0V
3
6
k
Ω
NEG Pump Efficiency
I
LOAD
= -100µA
97
%