Rainbow Electronics MAX1677 - Manual (Page 3)

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