LTC3901 datasheet(5/16 Pages) LINER

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LTC3901

3901f

TYPICAL PERFOR A CE CHARACTERISTICS

VCC Supply Current

vs Load Capacitance

CLOAD (nF)

TA = 25°C

3901 G16

VCC = 5V

VCC = 11V

PVCC (Pin 1): Driver Supply Input. This pin powers the

ME and MF drivers. Bypass this pin to PGND using a 4.7µF

low ESR capacitor in close proximity to the LTC3901. This

pin should be connected to the same supply voltage as the

VCC pin.

ME (Pin 2, 3): Driver Output for ME. This pin drives the

gate of the external N-channel MOSFET, ME.

PGND (Pin 4,13): Power Ground. Both drivers return to

this pin. Connect PGND to a high current ground node in

close proximity to the sources of ME and MF.

CSE+, CSE– (Pin 6, 5): ME Current Sense Differential

Input. Connect CSE+ through a series resistor to the drain

of ME and CSE– through a series resistor to the source of

ME. The LTC3901 monitors the CSE inputs 250ns after ME

goes high. If the inductor current reverses and flows into

ME causing CSE+ to rise above CSE–by more than 10.5mV,

the LTC3901 pulls ME low. See the Current Sense section

for more details on choosing the resistance values for

RCSE1 to RCSE3.

TIMER (Pin 7): Timer Input. Connect this pin to an external

R-C network to program the timeout period. The LTC3901

resets the timer at every positive and negative transition of

the SYNC input. If the SYNC signal is missing or incorrect,

the LTC3901 pulls both ME and MF low once the TIMER

pin goes above the timeout threshold. See the Timer sec-

tion for more details on programming the timeout period.

GND (Pin 8,10): Signal Ground. All internal low power

circuitry returns to this pin. To minimize differential ground

currents, connect GND to PGND right at the LTC3901.

SYNC (Pin 9): Driver Synchronization Input. 0V at this pin

forces both ME and MF high after an initial negative pulse.

A subsequent positive pulse at SYNC input forces ME to

pull low, whereas a negative pulse forces MF to pull low.

The SYNC signal should alternate between positive and

negative pulses. If the SYNC signal is incorrect, the LTC3901

pulls both MF and ME low.

CSF+, CSF– (Pin 11, 12): MF Current Sense Differential

Input. Connect CSF+ through a series resistor to the drain

of MF and CSF– through a series resistor to the source of

MF. The LTC3901 monitors the CSF inputs 250ns after MF

goes high. If the inductor current reverses and flows into

MF causing CSF+ to rise above CSF– by more than 10.5mV,

the LTC3901 pulls MF low. See the Current Sense section

for more details on choosing the resistance values for

RCSF1 to RCSF3.

MF (Pin 14, 15): Driver Output for MF. This pin drives the

gate of the external N-channel MOSFET, MF.

VCC (Pin 16): Power Supply Input. All internal circuits

except the drivers are powered from this pin. Bypass this

pin to GND using a 1µF capacitor in close proximity to the

LTC3901.

PI FU CTIO S

VCC Supply Current vs

Temperature

3901 G15

TEMPERATURE (°C)

–50

100

050

–25

125

CLOAD = 4.7nF

VCC = 5V

VCC = 11V

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