Maxim Integrated
│
3
MAX16126/MAX16127
Evaluation Kits
Evaluate: MAX16126/MAX16127
www.maximintegrated.com
Quick Start
Recommended Equipment
● MAX16126/MAX16127 EV kit
● ±25V, 50W DC power supply
● Electronic load
● Oscilloscope
● Digital voltmeter
Procedure (Full-Featured Solution: Circuit 1)
The EV kit is fully assembled and tested. Follow the steps
below to verify operation. Caution: Do not turn on the
power supply until all connections are completed.
1) Connect a DC power supply (0 to +35V) across the IN
and SYSGND PCB pads.
2) Connect a voltmeter or oscilloscope and a load (if
desired) between the OUT and SYSGND PCB pads.
3) Verify that a shunt is installed across jumper JU1,
connecting SHDN to IN.
4) Turn on the power supply and increase the input
voltage. The output turns on when the input voltage
exceeds +8V, the undervoltage set point. Increase the
input voltage; for the MAX16126, the output turns off
when the input voltage exceeds +32.1V, the overvolt-
age set point. For the MAX16127, the output stays lim-
ited at +32V at the overvoltage condition. Refer to the
MAX16126/MAX16127 IC data sheet for more details.
Detailed Description of Hardware
The MAX16126/MAX16127 EV kits demonstrate a high
overvoltage protection circuit for automotive applications
that must survive load-dump and high-voltage transient
conditions. Additional zener diodes at the input of the
ICs provide extended positive voltage-range protection
against higher voltage transients. The EV kits provide two
separate circuits for evaluation: A full-featured solution
and a minimum parts-count solution. The full-featured
solution provides a robust -60V to +90V protection range.
The minimum parts-count solution supports a protection
range of 0 to +60V.
The dual MOSFET (circuit #2) supplies 3A, while the
MOSFETs of the full-featured circuit (circuit #1) will
supply 5A when the input voltage remains between the
input UVP and OVP limits.
Overvoltage Protection
The devices feature overvoltage protection that monitors
either the input (MAX16126) or the output (MAX16127)
for overvoltage conditions through a resistive divider.
The MAX16126 features switch-mode fault management
for overvoltage conditions, while the MAX16127 features
voltage limiter-mode fault management for overvoltage
conditions.
Switch-Mode Fault Protection (MAX16126)
The MAX16126 features a switch-mode fault protection
that monitors the input voltage and turns off the back-to-
back MOSFETs by pulling the GATE to ground when an
overvoltage or undervoltage condition occurs. Depending
on the device configuration, during an overvoltage condi-
tion, the MAX16126 either latches off or enters an autore-
try mode during the overvoltage condition. Refer to the
MAX16126/MAX16127 IC data sheet for more details.
For the latchoff version, the latch is cleared by cycling the
input voltage (IN) below the undervoltage-lockout thresh-
old or by toggling SHDN. Use the following formula to set
a different overvoltage threshold for the MAX16126:
( )
OVTH
V R4
R3B R4 700
V
×
= −+Ω
where R4 is 10kΩ (typ), VTH is +1.225V for the OVSET
threshold, VOVTH is the desired overvoltage threshold,
and 700Ω is the typical on-resistance of the TERM switch.
This equation applies to the full-featured solution circuit
(circuit 1). For the minimum parts-count solution (bottom
portion), replace R3B = R15B and R4 = R23.
Voltage Limiter-Mode Fault
Protection (MAX16127)
The MAX16127 features a limiter-mode fault protection
that monitors the output voltage for an overvoltage condi-
tion using a resistive divider between OUT and OVSET.
During the overvoltage condition, the output is regulated at
the overvoltage-threshold voltage and continues to supply
power to downstream devices. If the overvoltage condition
lasts long enough to heat the MOSFETs, the MAX16127
could reach thermal limit and pull the GATE low until the
device cools by 20°C. Use the following formula to set a
different overvoltage threshold for the MAX16127:
( )
OVTH
TH
V R4
R3A R4 ,
V
×
= −
where R4 is 10kΩ (typ), VTH is +1.225V for the OVSET
threshold, and VOVTH is the desired overvoltage thresh-
old. This equation applies to the full-featured solution
circuit (top portion). For the minimum parts-count solution
(circuit 2), replace R3A = R15A and R4 = R23.