Pin description (continued) – Rainbow Electronics MAX8514 User Manual

Page 13

MAX8513/MAX8514

Wide-Input, High-Frequency, Triple-Output Supplies

with Voltage Monitor and Power-On Reset

______________________________________________________________________________________

Pin Description (continued)

PIN

NAME

MAX8513

MAX8514

FUNCTION

SEQ

Connect to VL for output tracking. Connect to GND for output staggered sequence.
Staggered sequence ramps up V

OUT2

and V

OUT3

softly to avoid glitches on the previous

voltage due to charging of the LDO’s output capacitors.

SYNC/EN

Shutdown Control and Synchronization Input. There are three operating modes:
• When SYNC/EN is low, the controller is off but the VL regulator is still running.
• When SYNC/EN is high, the controller is enabled with the switching frequency set by
R

FREQ

• When SYNC/EN is driven by an external clock, the controller is enabled and switches at
the external clock frequency.

N.C.

—

No Connection. Not internally connected. Connect to GND or leave floating.

SUP3N

—

OUT3N Base-Drive Supply. Connect SUP3N to any positive voltage between 1.5V and 5.5V
to provide power for the negative linear-regulator transistor driver.

DRV3P

—

OUT3P Base Drive. Connect DRV3P to the base of an external PNP pass transistor to form a
positive linear voltage regulator.

DRV3N

—

OUT3N Base Drive. Connect DRV3N to the base of an external NPN pass transistor to form
a negative linear voltage regulator.

Main Voltage Input (4.5V to 28V). Bypass IN to GND, close to the IC, with a minimum 1µF
ceramic capacitor (C2). IN powers the linear regulator whose output is VL.

POR

Power-On Reset. Open-drain output that goes high after all outputs reach the regulation
limit and a 315ms delay time has elapsed.

FB3P

—

OUT3P Feedback Input. FB3P is referenced to 0.8V and connects to a resistive-divider
(R13, R14) to control a positive linear voltage regulator.

FB3N

—

OUT3N Feedback Input. Connect a resistive-divider (R13, R14) from OUT1 to FB3N to
OUT3N to regulate FB3N to 0V.

ILIM

ILIM Set Input. Connect a resistive-divider (R17, R18) from OUT1 to ILIM to GND. See the
Current Limit section.

CSP

Positive Current-Sense Input. Used to detect OUT1 current limit.

CSN

Negative Current-Sense Input. Used to detect OUT1 current limit.

Anal og S oft- S tar t C ontr ol Inp ut. Thi s p i n g oes i nto the p osi ti ve i np ut of the V OU T1’ s er r or
am p l i fi er . W hen the M AX 8513/M AX 8514 ar e tur ned on, S S i s at GN D and char g es up to 1.25V
w i th a constant 25µA. C onnect a cap aci tor ( C 13) fr om S S to G N D for the d esi r ed soft- star t ti m e.