Rainbow-electronics MAX1677 Instrukcja Użytkownika Pobierz pdf (Strona 3)

MAX1677

Compact, High-Efficiency, Dual-Output

Step-Up and LCD Bias DC-DC Converter

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ELECTRICAL CHARACTERISTICS (continued)

OUT

= 3.3V, C

REF

= 0.1µF, POUT = OUT, T

= 0°C to +85°C, unless otherwise noted. Typical values are at T

= +25°C.)

CONDITIONS

N-channel 0.22 0.5

Ω

P-channel 0.4 1.0

LX Current Limit

LX(PWM)

N-channel PWM mode 550 670 800

UNITSMIN TYP MAXPARAMETER

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

ON(LOW)

ON(HIGH)

LCDON, LCDPOL, CLK/SEL

Input Threshold

OUT

> 2.5V

0.2V

OUT

0.8V

OUT

LBI Falling Threshold V

LBI(TH)

599 614 629 mV

LBI Hysteresis 1 %

LBO Output Low Voltage

LBO(LO)

Sink current = 1mA 0.1 V

LBI Input Bias Current I

LBI(BIAS)

50 nA

LBO Leakage Current

LBO(LEAK)

LBO

= 5.5V 1 µA

LCDLX Voltage 28 V

LCDPOL connected to OUT or GND through

50kΩ

150 225 300

LCDLX Switch Resistance RLCDLX 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

LOAD

= 5mA, V

= 1.2V to 3.6V,

Figure 2

0.1 %/V

LCD Load Regulation

LOAD

= 0 to 5mA, V

= 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

LX On-Resistance

SYMBOL

LX(ON)N

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

LCDPOL = GND 0.5

LOGIC AND CONTROL INPUTS

1 2 3 4 5 6 7 8 ... 15 16

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