MAX15009 Datasheet, PDF(13/23 Page) Maxim Integrated Products – Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector

English

English German Russian Spanish Italian Polish Chinese Japanese Korean French Portuguese	Language :

MAX15009 Datasheet, PDF (13/23 Pages) Maxim Integrated Products – Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector

◁

Automotive 300mA LDO Regulators with

Switched Output and Overvoltage Protector

Detailed Description

The MAX15009/MAX15011 integrate a 300mA LDO

voltage regulator, a current-limited switched output,

and an OVP controller (MAX15009 only). These devices

operate over a wide supply voltage range from 5V to

40V and are able to withstand load-dump transients up

to 45V.

The MAX15009/MAX15011 feature a 300mA LDO regu-

lator that consumes 70ÂµA of current under light-load

conditions and feature a fixed 5V or an adjustable out-

put voltage (1.8V to 11V). Connect FB_LDO to ground

to select a fixed 5V output voltage or select the LDO

output voltage by connecting an external resistive volt-

age-divider at FB_LDO. The regulator sources at least

300mA of current and includes a current limit of 330mA

(min). Enable the LDO by pulling EN_LDO high.

The switch features accurate current-limit sensing cir-

cuitry and is capable of controlling remote loads. Once

enabled, an internal charge pump generates the over-

drive voltage for an internal MOSFET. The switch then

starts to conduct and OUT_SW is charged up to

VOUT_LDO. The switch is enabled when the output volt-

age of the LDO is above the RESET threshold voltage

(92.5% of the LDO nominal output value).

An overcurrent condition exists when the current at

OUT_SW, IOUT_SW, exceeds the 200mA (typ) internal

factory-set current-limit threshold or the externally

adjustable current-limit threshold. During a continuous

overcurrent event, the capacitor connected at

OC_DELAY, COC_DELAY, is charged up to a voltage of

1.235V with a current, IOC_DELAY_UP. When this voltage

is reached, an overcurrent latch is set and the gate of

the internal MOSFET is discharged, reducing IOUT_SW.

COC_DELAY is then discharged through a pulldown cur-

rent, IOC_DELAY_DOWN (IOC_DELAY_UP / 16) and the

internal MOSFET remains off until COC_DELAY has been

discharged to 0.1V. After this user-programmable turn-

off delay, the switch turns back on. This charge/

discharge is repeated if the overcurrent condition per-

sists. The switch returns to normal operation once the

overcurrent condition has been removed.

The OVP controller (MAX15009 only) relies on an exter-

nal MOSFET with adequate voltage rating (VDSS) to

protect downstream circuitry from overvoltage tran-

sients. The OVP controller drives the gate of the exter-

nal n-channel MOSFET, and is configurable to operate

as an overvoltage protection switch or as a closed-loop

voltage limiter.

GATE Voltage (MAX15009 Only)

The MAX15009 uses a high-efficiency charge pump to

generate the GATE voltage for the external n-channel

MOSFET. Once the input voltage, VIN, exceeds the

undervoltage lockout (UVLO) threshold, the internal

charge pump fully enhances the external n-channel

MOSFET. An overvoltage condition occurs when the

voltage at FB_PROT goes above the threshold voltage,

VTH_PROT. After VTH_PROT is exceeded, GATE is quick-

ly pulled to PGND with a 63mA pulldown current. The

MAX15009 includes an internal clamp from GATE to

SOURCE that ensures that the voltage at GATE never

exceeds one diode drop below SOURCE during gate

discharge. The voltage clamp also prevents the GATE-

to-SOURCE voltage from exceeding the absolute maxi-

mum rating for the VGS of the external MOSFET in case

the source terminal is accidentally shorted to 0V.

Overvoltage Monitoring (MAX15009 Only)

The OVP controller monitors the voltage at FB_PROT

and controls an external n-channel MOSFET, isolating,

or limiting the load during an overvoltage condition.

Operation in OVP switch mode or limiter mode

depends on the connection between FB_PROT and the

external MOSFET.

Overvoltage Switch Mode

When operating in OVP switch mode, the FB_PROT

divider is connected to the drain of the external MOS-

FET. The feedback path consists of the voltage-divider

tapped at FB_PROT, FB_PROTâs internal comparator,

the internal gate charge pump/gate pulldown, and the

external n-channel MOSFET (Figure 1). When the pro-

grammed overvoltage threshold is exceeded, the inter-

nal comparator quickly pulls GATE to ground and turns

VIN

GATE

MAX15009

FB_PROT

SOURCE

SGND

PROTECTOR

OUTPUT

Figure 1. Overvoltage-Limiter Switch Configuration (MAX15009)

______________________________________________________________________________________ 13

▷