Datasheet

MAX8795A
TFT-LCD DC-DC Converter with
Operational Amplifiers
_______________________________________________________________________________________ 7
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 3V, V
MAIN
= V
SUP
= 14V, V
PGND
= V
AGND
= V
BGND
= 0V, I
REF
= 25µA, T
A
= 0°C to +105°C. Typical values are at T
A
= +25°C,
unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
MAIN STEP-UP REGULATOR
Output Voltage Range
V
MAIN
V
IN
18 V
Operating Frequency f
OSC
1000 1200 1400 kHz
Oscillator Maximum Duty Cycle 86 90 93 %
T
A
= +25°C to +105°C 1.221 1.233 1.245
FB Regulation Voltage V
FB
No load
T
A
= 0°C to +105°C 1.212 1.233 1.248
V
FB Fault Trip Level V
FB
falling 1.10 1.14 1.17 V
FB Load Regulation 0 < I
MAIN
< full load, transient only -1
FB Line Regulation V
IN
= 2.5V to 6V 0.1 ±0.4 %/V
FB Input Bias Current V
FB
= 1.233V +100 +200 nA
FB Transconductance ∆I
COMP
= ±2.5µA 75 160 280
µS
FB Voltage Gain From FB to COMP 700 V/V
LX On-Resistance R
LX
(
ON
)
I
LX
= 200mA 160 300 mΩ
LX Leakage Current I
LX
V
LX
= 19V 10 20 µA
LX Current Limit
I
LIM
V
FB
= 1.2V, duty cycle = 75% 2.5 3.0 3.5
A
Current-Sense Transresistance 0.1 0.2 0.3 V/A
Soft-Start Period t
SS
14 ms
Soft-Start Step Size
V
REF
/
128
V
OPERATIONAL AMPLIFIERS
SUP Supply Range V
SUP
6.0 18.0
SUP Overvoltage Fault Threshold 18.0 19 19.9
V
SUP Supply Current I
SUP
Buffer configuration, V
POS_
= V
SUP
/ 2,
no load
3.5 5.0 mA
Input Offset Voltage V
OS
(V
NEG_
, V
POS
_, V
OUT_
) ≅ V
SUP
/ 2 0 12 mV
Input Bias Current I
BIAS
(V
NEG_
, V
POS_
, V
OUT_
) ≅ V
SUP
/ 2 -50 0 +50 nA
Input Common-Mode Voltage
Range
V
CM
0V
SUP
V
Common-Mode Rejection Ratio CMRR 0 ≤ (V
NEG_
, V
POS_
) ≤ V
SUP
45 80 dB
Open-Loop Gain 125 dB
Output Voltage Swing, High V
OH
I
OUT_
= 5mA
V
SUP
-
100
V
SUP
-
50
mV
Output Voltage Swing, Low V
OL
I
OUT_
= -5mA 50 100 mV
Short-Circuit Current To V
SUP
/ 2, source or sink 75 130 mA
Power-Supply Rejection Ratio PSRR
DC, 6V ≤ V
SUP
≤ 18V,
(V
NEG_
, V
POS_
) ≅ V
SUP
/ 2
60 dB
Slew Rate 45
V/µs
-3dB Bandwidth R
L
= 10kΩ, C
L
= 10pF, buffer configuration 20 MHz