Datasheet
MAX1997/MAX1998
Quintuple/Triple-Output TFT LCD Power Supplies
with Fault Protection and VCOM Buffer
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
IN
= 3V, V
DDB
= 10V, SHDN = ONDC = FREQ = IN, C
REF
= 0.22µF, PGND = GND, T
A
= 0°C to +85°C.
Typical values are at T
A
= +25°C, unless otherwise noted.)
PARAMETER CONDITIONS
MIN TYP MAX
UNITS
Oscillator Maximum Duty Cycle 80 85 90 %
FB Regulation Voltage I
LX
= 200mA
1.229 1.242 1.254
V
FB Fault Trip Level V
FB
falling
0.96 1.00
1.04 V
FB Load Regulation I
MAIN
= 0 to full load
-1.6
%
FB Line Regulation V
IN
= 2.7V to 5.5V 0.2 0.4
%/V
FB Input Bias Current V
FB
= 1.5V
-100
+100
nA
LX On-Resistance
250
450 mΩ
LX Leakage Current V
LX
= 13V
0.01
20 µA
LX Current Limit 1.6 2.1 2.8 A
LX RMS Current Rating (Note 2) 1.4 A
Soft-Start Period 4096/f
OSC
s
Soft-Start Step Size V
REF
/32 V
POSITIVE LINEAR-REGULATOR CONTROLLERS (REG P, REG 1, AND REG 2)
I
DRVP
= 100µA
I
DRV1
= 1350µA (MAX1997 only) FB_ Regulation Voltage
I
DRV2
= 335µA (MAX1997 only)
1.225 1.250 1.275
V
FB_ Fault Trip Level V
FB
_ falling
0.96 1.00
1.04 V
FB_ Input Bias Current V
FB
_ = 1.25V
-250
+250
nA
V
DRVP
= 10V, I
DRVP
= 0.05mA to 1mA
V
DRV1
= 10V, I
DRV1
= 0.5mA to 5mA
(MAX1997 only)
FB_ Effective Load Regulation Error
(Transconductance)
V
DRV2
= 10V, I
DRV2
= 0.1mA to 2mA
(MAX1997 only)
-1.5
-2 %
I
DRVP
= 100µA, 2.7V < V
IN
< 5.5V
I
DRV1
= 1350µA, 2.7V < V
IN
< 5.5V
(MAX1997 only)
FB_ Line (IN) Regulation Error
I
DRV2
= 335µA, 2.7V < V
IN
< 5.5V
(MAX1997 only)
1 mV
Bandwidth (Note 2)
1000
kHz
DRVP Sink Current 2 3.3
DRV1 Sink Current (MAX1997 only) 5 18
DRV2 Sink Current (MAX1997 only)
V
FB
_ = 1.1V, V
DRV
_ = 10V
5 15
mA
DRV_ Leakage Current V
FB
_ = 1.5V, V
DRV
_ = 28V 0.1 10 µA
Soft-Start Period 4096/f
OSC
s
Soft-Start Step Size V
REF
/32 V
NEGATIVE LINEAR-REGULATOR CONTROLLER (REG N)
FBN Regulation Voltage I
DRVN
= 100µA 95
125
155 mV
FBN Fault Trip Level V
FBN
rising
325 370
475 mV
FBN Input Bias Current V
FBN
= 0V
-200
+200
nA