Rainbow Electronics MAX15010 - Manual (Page 13)

Detailed Description
The MAX15008/MAX15010 integrate a 300mA LDO
voltage regulator, a voltage tracker, and an OVP con-
troller. These devices operate over a wide 5V to 40V
supply voltage range and are able to withstand load-
dump transients up to 45V.
The MAX15008/MAX15010 feature a 300mA LDO regu-
lator that consumes less than 70µA of current under
light-load conditions and feature a fixed 5V or an
adjustable output 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 voltage-divider at FB_LDO. The regu-
lator sources at least 300mA of current and includes a
current limit of 330mA (min). Enable the LDO by pulling
EN_LDO high.
The tracker can be powered from the LDO input sup-
ply voltage or an independent voltage source. It is
designed to supply power to a remote sensor and is
able to handle the severe conditions in automotive
applications. Set the tracker output voltage by con-
necting a resistive voltage-divider to OUT_TRK and
connecting ADJ to the tracking source. The tracker
feedback, FB_TRK, and a separate tracker reference
voltage input, ADJ, offer the flexibility of setting the
tracker output to be lower, equal to, or higher than the
main (LDO) output. Pull EN_TRK to SGND to turn the
tracker off and keep the device in always-on, low-
quiescent-current operation.
The OVP controller (MAX15008 only) relies on an exter-
nal MOSFET with adequate voltage rating (V
DSS ) 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 (MAX15008 Only)
The MAX15008 uses a high-efficiency charge pump to
generate the GATE voltage for the external n-channel
MOSFET. Once the input voltage, V
IN
, 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,
V
TH_PROT . After V TH_PROT is exceeded, GATE is quick-
ly pulled to PGND with a 63mA pulldown current. The
MAX15008 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 V
GS of the external MOSFET in case
the source terminal is accidentally shorted to 0V.
Overvoltage Monitoring (MAX15008 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
MOSFET. The feedback path consists of the voltage-
divider tapped at FB_PROT, FB_PROT’s internal
comparator, the internal gate charge pump/gate
pulldown, and the external n-channel MOSFET (Figure
1). When the programmed overvoltage threshold is
exceeded, the internal comparator quickly pulls GATE
to ground and turns off the external MOSFET,
disconnecting the power source from the load. In this
configuration, the voltage at the source of the
MOSFET is not monitored. When the voltage at
FB_PROT decreases below the overvoltage threshold,
the MAX15008 raises the voltage at GATE, reconnecting
the load to the power source.
MAX15008/MAX15010
Automotive 300mA LDO Voltage Regulators
with Tracker Output and Overvoltage Protector
______________________________________________________________________________________ 13
IN V IN
FB_PROT
SGND
GATE
SOURCE
PROTECTOR
OUTPUT
MAX15008
Figure 1. Overvoltage Switch Configuration (MAX15008)