MAX1778/MAX1880–MAX1885
Quad-Output TFT LCD DC-DC
Converters with Buffer
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +3.0V, SHDN = IN, V
SUPP
= V
SUPN
= V
SUPB
= V
SUPL
= 10V, LDOOUT = FBL, BUF- = BUFOUT, BUF+ = FLTSET = TGND =
PGND = GND, C
REF
= 0.22µF, C
BUF
= 1µF, T
A
= 0°C to +85°C. Typical values are at T
A
= +25°C, unless otherwise noted.)
PARAMETER SYMBOL
CONDITIONS MIN TYP MAX
UNITS
MAIN STEP-UP CONVERTER
Main Output Voltage Range V
MAIN
V
IN
13
V
Integrator enabled, C
INTG
= 1000pF 1.234 1.247 1.260
FB Regulation Voltage V
FB
Integrator disabled (INTG = REF) 1.220 1.280
V
FB Input Bias Current I
FB
V
FB
= 1.25V, INTG = GND -50 +50
nA
MAX1778/MAX1880/MAX1883 0.85 1 1.15
MHz
Operating Frequency f
OSC
MAX1881/MAX1882/MAX1884/MAX1885 425 500 575
kHz
Oscillator Maximum Duty
Cycle
80 85 91 %
Integrator enabled,
C
INTG
= 1000pF
0.01
Load Regulation
I
LX
= 0 to 200mA,
V
MAIN
= 10V
Integrator disabled
(INTG = REF)
0.2
%
Line Regulation 0.1 %/V
Integrator Transconductance 317 µs
LX Switch On-Resistance R
LX
ON
I
LX
= 100mA 0.35 0.7 Ω
LX Leakage Current I
LX
V
LX
= 13V 0.01 20 µA
Phase I = soft-start (1024/f
OSC
) 0.275 0.38 0.5
Phase II = soft-start (1024/f
OSC
) 0.75
Phase III = soft-start (1024/f
OSC
) 1.12
LX Current Limit I
LIM
Phase IV = fully-on (after 3072/f
OSC
) 1.15 1.5 1.85
A
Maximum RMS LX Current 1A
Soft-Start Period t
SS
Power-up to the end of Phase III 3072 / f
OSC
s
Falling edge, FLTSET = GND 1.07 1.1 1.14
FB Fault Trip Level
Falling edge, FLTSET = 1V 0.955 0.99 1.025
V
POSITIVE CHARGE PUMP (MAX1778/MAX1880/MAX1881/MAX1882 ONLY)
SUPP Input Supply Range
V
SUPP
2.7 13 V
Operating Frequency f
CHP
0.5 x f
OSC
Hz
FBP Regulation Voltage V
FBP
1.2 1.25 1.3
V
FBP Input Bias Current I
FBP
V
FBP
= 1.5V -50 +50
nA
DRVP PCH On-Resistance R
PCH
ON
510
Ω
V
FBP
= 1.2V 2 4
Ω
DRVP NCH On-Resistance R
NCH
ON
V
FBP
= 1.3V 20
kΩ
Maximum RMS DRVP Current 0.1
A
FBP Power-Ready Trip Level Rising edge 1.09 1.125 1.16
V
Falling edge, FLTSET = GND 1.08 1.11 1.16
FBP Fault Trip Level
Falling edge, FLTSET = 1V 0.955 0.99 1.025
V
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