Compact, High-Efficiency, Dual-Output
Step-Up and LCD Bias DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(V
OUT
= 3.3V, C
REF
= 0.1µF, POUT = OUT,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
LX On-Resistance
LX Current Limit
P-Channel Synchronous Rectifier
Turn-Off Current in PFM Mode
Internal Oscillator
Oscillator Maximum Duty Cycle
External Clock Frequency
Range
LOGIC AND CONTROL INPUTS
Input Leakage Current
ON Input Threshold
LCDON, LCDPOL, CLK/SEL
Input Threshold
LBI Falling Threshold
LBI Hysteresis
LBO
Output Low Voltage
LBI Input Bias Current
LBO
Leakage Current
LCD BIAS DC-DC
LCDLX Voltage
LCDPOL = OUT or GND
LCDLX Switch Current Limit
LCDLX Switch Resistance
LCDLX Leakage Current
LCDFB Set Point
LCDFB Input Bias Current
LCD Line Regulation
LCD Load Regulation
Maximum LCDLX On-Time
Minimum LCDLX Off-Time
LCDFB Voltage for
Start-Up Mode
t
ON LCD
Operating mode
Start-up mode (positive or negative)
LCDPOL = OUT
LCDPOL = GND
I
LOAD
= 5mA, V
IN
= 1.2V to 3.6V,
Figure 2
I
LOAD
= 0 to 5mA, V
IN
= 2.4V,
Figure 2
3.4
0.8
3.0
0.1
0.5
4.3
1
4.0
0.75
0.5
5.2
1.2
5.0
R
LCDLX
LCDPOL connected to OUT or GND through
50kΩ
V
OUT
= 3.3V
V
LCDLX
= 28V
Positive LCD, LCDPOL = OUT
Negative LCD, LCDPOL = GND
1.225
-15
1.25
0
300
150
350
225
1.0
28
450
300
1.4
1
1.275
15
50
mA
Ω
µA
V
mV
nA
%/V
%
µs
µs
V
V
V
LBO(LO)
I
LBI(BIAS)
I
LBO(LEAK)
V
LBO
= 5.5V
Sink current = 1mA
V
ON(LOW)
V
ON(HIGH)
V
IL
V
IH
V
LBI(TH)
ON, LCDON, LCDPOL, CLK/SEL
1.1V < V
OUT
< 5.5V
V
OUT
> 2.5V
0.8V
OUT
0.2V
OUT
0.8V
OUT
599
614
1
0.1
50
1
629
1
0.2V
OUT
µA
V
V
mV
%
V
nA
µA
f
D
CLK/SEL = OUT
SYMBOL
R
LX(ON)N
R
LX(ON)P
I
LX(PWM)
I
LX(PFM)
N-channel
P-channel
N-channel PWM mode
N-channel PFM mode
550
250
40
240
80
200
CONDITIONS
MIN
TYP
0.22
0.4
670
350
90
300
85
MAX
0.5
1.0
800
450
140
360
90
400
UNITS
Ω
mA
mA
kHz
%
kHz
MAX1677
3
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