MAX1677 datasheet(4/16 Pages) MAXIM

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Compact, High-Efficiency, Dual-Output

Step-Up and LCD Bias DC-DC Converter

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Note 1: The MAX1677 operates in bootstrap mode (operates from the output voltage). Once started, it will operate down to 0.7V

input. If VIN exceeds the set VOUT, VOUT will follow one diode drop below VIN.

Note 2: CREF = 0.22µF for applications where IREF > 10µA.

Note 3: In low-power mode (CLK/SEL = GND), the output voltage regulates 1% higher than in low-noise mode (CLK/SEL = OUT or

synchronized).

Note 4: The device is in a startup mode when VOUT is below this value.

Note 5: Specifications to -40°C are guaranteed by design and not production tested.

ELECTRICAL CHARACTERISTICS

(VOUT = 3.3V, CREF = 0.1µF, POUT = OUT, TA = -40°C to +85°C, unless otherwise noted. ) (Note 5)

LBO Output Low Voltage

V LBO(LO)

Sink current = 1mA

LCDPOL = OUT or GND

300

450

0.1

µA

Supply Current

Main DC On, LCD Off

Supply Current All On,

Main DC-DC in PFM Mode

IPFM

No load, current into OUT

µA

FB Regulation Voltage

µA

LX Leakage Current

Startup to Normal Mode Transition

Voltage (Note 4)

CONDITIONS

VLOCKOUT

2.1

2.4

ILX(LEAK)

Output Voltage

VOUT

FB = GND, 0

≤ ILX ≤ 350mA,

CLK/SEL = OUT (Note 3)

3.17

3.46

VFB(REG)

Adjustable mode, CLK/SEL = OUT (Note 3)

1.22

1.28

µA

Supply Current All On,

Main DC-DC in PWM Mode

Supply Current in Shutdown

µA

IPWM

No load, current into OUT

300

ILCDOFF

No load, current into OUT

LX Current Limit

ILX(PWM)

N-channel PWM mode

550

900

UNITS

MIN

MAX

SYMBOL

PARAMETER

ILX(PFM)

N-channel PFM mode

250

500

Internal Oscillator

CLK/SEL = OUT

240

360

kHz

External Clock Frequency Range

200

400

kHz

ON Input Threshold

VON(LOW)

1.1V < VOUT < 5.5V

0.2VOUT

VON(HIGH)

0.8VOUT

LCDON, LCDPOL, CLK/SEL

Input Threshold

VIL

0.2VOUT

VIH

0.8VOUT

LBI Falling Threshold

VLBI(TH)

599

629

LCD BIAS DC-DC

LCDLX Switch Current Limit

LCDPOL connected to OUT or GND

through 50k

Ω

150

300

LCDFB Set Point

Positive LCD, LCDPOL = OUT

1.22

1.28

-20

+20

Negative LCD, LCDPOL = GND

GENERAL

MAIN

LCD BIAS DC-DC

LOGIC

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