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DS20005208B-page 3

MCP1643

1.0

ELECTRICAL CHARACTERISTICS

Absolute Maximum Ratings †

EN, FB, VIN, VSW, VOUT - GND................................................................................................................................+6.5V

EN, FB ..............................................................................................................< maximum VOUT or VIN > (GND – 0.3V)

Output Short Circuit Current............................................................................................................................ Continuous

Power Dissipation ................................................................................................................................. Internally Limited

Storage Temperature ..............................................................................................................................-65°C to +150°C

Ambient Temp. with Power Applied...........................................................................................................-40°C to +85°C

Operating Junction Temperature.............................................................................................................-40°C to +125°C

ESD Protection On All Pins:

HBM ................................................................................................................................................................... 4 kV

MM ....................................................................................................................................................................300V

†Notice: Stresses above those listed under “Maximum Ratings” may cause permanent damage to the

device. This is a stress rating only and functional operation of the device at those or any other conditions

above those indicated in the operational sections of this specification is not intended. Exposure to maxi-

mum rating conditions for extended periods may affect device reliability.

DC CHARACTERISTICS

Electrical Characteristics: Unless otherwise indicated, VIN = EN = 1.2V, COUT =20µF, CIN =10µF, L = 4.7µH,

ILED =25mA, TA =+25°C. Boldface specifications apply over the TA range of -40°C to +85°C.

Parameters

Sym

Min

Typ

Max

Units

Conditions

Input Characteristics

Minimum Input Voltage

After Start-Up

VIN

—0.5

—

V

Note 1, Note 3

Start-Up Voltage

VIN

—0.65

0.8

V

Note 2, Note 1

Output Overvoltage

Protection

VOUT_OVP

—5.0

—

V

Note 3

Shutdown

Quiescent Current

IQSHDN

—

1.2

—

µA

EN = GND;

includes N-Channel and

P-Channel Switch Leakage

Feedback Voltage

VFB

105

120

135

mV

—

Feedback Input

Bias Current

IVFB

—60

—

pA

—

NMOS Switch Leakage

INLK

—0.4

—

µA

VIN =VSW =4.0V

VOUT =4.5V

VEN =VFB =GND

PMOS Switch Leakage

IPLK

—0.25

—

µA

VIN =VSW = GND;

VOUT =4.5V

NMOS Switch

ON Resistance

RDS(ON)N

—0.2

—



ILED = 250 mA, (Note 3)

PMOS Switch

ON Resistance

RDS(ON)P

—0.4

—



ILED = 250 mA, (Note 3)

NMOS Peak

Switch Current Limit

IN(MAX)

—1.6

—

A

Note 3

Maximum Duty Cycle

DCMAX

—90

—

%

Note 3

Note 1: For VIN <VOUT, ILED remains in regulation up to VIN =VLED minus a headroom @ LED typical VF and IF.

2: VOUT completely discharged. If the output capacitor remains partially charged, the device will start-up at

the minimum possible voltage.

3: Determined by characterization, not production tested.