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Axelite Confidential Materials, do not copy or distribute without written consent.

Rev.2.0 Nov.16, 2011

AX6604/5

Note 1: VIN (min) =VOUT+VDROP

Note 2: Current limit is measured at constant junction temperature by using pulsed testing with a low ON time.

Note 3: Regulation is measured at constant junction temperature by using pulsed testing with a low ON time.

Note 4: Guaranteed by design.



APPLICATION CIRCUIT

C

IN

1uF

VOUT2

VOUT1

GND

OUT2

C

VOUT2

OUT1

C

AX6604/5

1uF

1uF

OUT1

V

EN1

EN2

VIN

V

IN



FUNCTION DESCRIPTIONS

The AX6604/5 is a highly accurate, dual, low noise, CMOS LDO voltage regulators

with enable function. The output voltage for each regulator is set independently by fuse

trimming. As illustrated in function block diagram, it consists of a reference, error amplifier, a

P-channel pass transistor, an ON/OFF control logic and an internal feedback voltage divider.

The band gap reference is connected to the error amplifier, which compares the reference

with the feedback voltage and amplifies the voltage difference. If the feedback voltage is

lower than the reference voltage, the pass- transistor gate is pulled lower, which allows more

current to pass to the VOUT pin and increases the output voltage. If the feedback voltage is

too high, the pass transistor gate is pulled up to decrease the output voltage. The output

voltage is feed back through an internal resistive divider connected to VOUT pin. Additional

blocks include an output current limiter, thermal sensor, and shutdown logic.

Enable Function

EN1 and EN2 pin start and stop the corresponding outputs independently. When the

EN pin is switched to the power off level, the operation of all internal circuit stops, the

build-in P-channel MOSFET output transistor between pins VIN and VOUT is switched off,

allowing current consumption to be drastically reduced.

Dropout Voltage

A regulator’s minimum input-output voltage differential, or dropout voltage, determines

the lowest usable supply voltage. The AX6604/5 use a P- channel MOSFET pass transistor,

its dropout voltage is function of drain-to-source on-resistance RDS (ON) multiplied by the load

current.

VDROPOUT = VIN - VOUT = RDS(ON) * IOUT