Datasheet

MAX17497A Evaluation Kit
Evaluates: MAX17497A
4Maxim Integrated
Current Limiting
The IC features current limiting for the transformer’s
primary side by monitoring the peak current entering
the IC LXF input. Resistor R15 sets the EV kit circuit
current limit to 548mA. The IC turns off switching MOSFET
N1 when the peak current at the LXF pin reaches the
current limit.
To reconfigure the peak current limit to a different value,
use the following equation to choose a new R15 resistor:
R15 = 50 x I
PEAK
where I
PEAK
is in amps and R15 is in kI.
When the instantaneous peak current through the LXF pin
reaches a level 20% higher than the programmed peak
current limit, then the IC enters into hiccup mode, which
keeps the respective converters in shutdown mode and
retries after 32ms. This limits the average short-circuit
current equal to:
I
SS
= I
PEAK
x t
SS
/(t
SS
+ t
HICCUP
)
where t
HICCUP
is 32ms and t
SS
is the short-circuit time
duration.
Undervoltage (UVLO)
and Overvoltage (OVI) Lockout
The EV kit features UVLO and OVI circuit protection
that prevent operation below the programmed input
supply start voltage. Resistors R9–R12 set the under-
voltage-threshold level. Resistors R13 and R14 set the
overvoltage-threshold levels. The EV kit circuit under-
voltage and overvoltage are set to +78V and +422V,
respectively. To reconfigure the OVLO and UVLO, refer
to the Startup Voltage and Input Overvoltage-Protection
Setting (EN/UVLO, OVI) section in the MAX17497A/
MAX17497B IC data sheet.
Open-Drain Output (RESETN)
The EV kit provides a PCB pad to monitor the status of the
open-drain output (RESTN). RESETN is high when VOUT
is within 5% of its regulated voltage. When VOUT falls
below 92% (typ) of its regulated voltage, RESETN is pulled
low. RESETN is pulled up to VCC through resistor R20.