Rainbow Electronics MAX8514 - Manual (Page 13)

MAX8513/MAX8514
Wide-Input, High-Frequency, Triple-Output Supplies
with Voltage Monitor and Power-On Reset
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Pin Description (continued)
PIN
NAME
MAX8513 MAX8514 FUNCTION
SEQ 18 18
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 19 19
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. 20 — No Connection. Not internally connected. Connect to GND or leave floating.
SUP3N — 20
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 21 —
OUT3P Base Drive. Connect DRV3P to the base of an external PNP pass transistor to form a
positive linear voltage regulator.
DRV3N — 21
OUT3N Base Drive. Connect DRV3N to the base of an external NPN pass transistor to form
a negative linear voltage regulator.
IN 22 22
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 23 23
Power-On Reset. Open-drain output that goes high after all outputs reach the regulation
limit and a 315ms delay time has elapsed.
FB3P 24 —
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 — 24
OUT3N Feedback Input. Connect a resistive-divider (R13, R14) from OUT1 to FB3N to
OUT3N to regulate FB3N to 0V.
ILIM 25 25
ILIM Set Input. Connect a resistive-divider (R17, R18) from OUT1 to ILIM to GND. See the
Current Limit section.
CSP 26 26 Positive Current-Sense Input. Used to detect OUT1 current limit.
CSN 27 27 Negative Current-Sense Input. Used to detect OUT1 current limit.
SS 28 28
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.