Dual, High-Efficiency, Step-Down

Controller with High Impedance in Shutdown

6

_______________________________________________________________________________________

0

0.01

10

1

0.1

300

350

400

200

250

100

150

50

LOAD CURRENT (A)

FREQUENCY vs. LOAD CURRENT

OUT1, SKIP = GND

OUT2, SKIP = GND

0

50

100

150

200

250

300

350

400

48

12

16

20

24

INPUT VOLTAGE (V)

FREQUENCY vs. INPUT VOLTAGE

OUT1

OUT2

__________________________________________Typical Operating Characteristics

ELECTRICAL CHARACTERISTICS (continued)

Note 2: When the inductor is in continuous conduction, the output voltage will have a DC regulation level higher than the error-compara-

tor threshold by 50% of the output voltage ripple. In discontinuous conduction (SKIP = AGND, light load), the output voltage

has a DC regulation higher than the error-comparator threshold by approximately 1.5% due to slope compensation.

Note 3: On-time and off-time specifications are measured from the 50% point to the 50% point at DH_ with LX_ = GND, BST_ = 5V,

and a 250pF capacitor connected from DH_ to LX_. Actual in-circuit times may differ due to MOSFET switching speeds.

Note 4: Production testing limitations due to package handling require relaxed maximum on-resistance specifications for the QFN

package. The MAX8743EEI and MAX8743ETX contain the same die, and the QFN package imposes no additional resis-

tance in-circuit.

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

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

35

65

Current-Limit Threshold

(Adjustable)

80

120

mV

Threshold

Rising edge, hysteresis = 20mV, PWMs

disabled below this level

4.05

4.40

V

ON_, SKIP

2.4

Logic Input High Voltage

UVP

0.4

V

ON_, SKIP

0.8

Logic Input Low Voltage

UVP

0.05

V

+3

Logic Input Current

ON_, SKIP, UVP

-1

+1

µA