Datasheet

transient in this mode, the MOSFET switches off until

the output voltage falls to 95% of the threshold voltage,

and then the MOSFET switches back on. This cycle

repeats, generating a sawtooth waveform on the output.

The minimum output voltage in overvoltage limiter

mode depends on load current, output capacitance,

and the MOSFET’s switching period. The MAX6495 EV

kit comes with one 22µF capacitor at the output to sup-

ply the load during the time when the MOSFET is off.

Connect the optional electrolytic capacitor C13 (150µF,

100V) to support load currents higher than 0.5A when

the EV kit operates in overvoltage limiter mode.

Add capacitor C3 on the gate of MOSFET M1 to

decrease the frequency of the sawtooth waveform. This

process helps limit the device’s power dissipation.

Jumper Selection

To filter fast transients that may be present at the input

from reaching the MAX6495, place a small resistor, R4,

(10Ω, for example) on the board, and cut jumper J1.

Three-pin jumper J2 selects between overvoltage mode

and overvoltage limiter mode; do not leave this jumper

unconnected. Three-pin jumper J3 controls the gate

drive of p-channel MOSFET M3 used as a reverse-bat-

tery protection. Use J3 to disconnect resistor R5 when

M3 is not used to avoid supply leakage through R5.

Three-pin jumper J4 controls the SHDN pin of the

MAX6495 and can enable or disable the MOSFET M1

enhancement. Table 1 lists the jumper options.

Evaluates: MAX6495

MAX6495 Evaluation Kit

_______________________________________________________________________________________ 3

SHUNT POSITION AND FUNCTION

JUMPER

1-2 2-3

J1 Shorted: RC input filter disabled*

Overvoltage mode*

Overvoltage limiter mode

M2 gate drive is

disabled*

M2 gate drive is enabled

J4 U1 is enabled* U1 is disabled

Table 1. Jumper Function

*Default configuration.