MAX15091 Datasheet, PDF (12/15 Pages) Maxim Integrated Products – Solution with Current Report Output

MAX15091/MAX15091A
2.7V to 18V, 9A, Integrated Hot-Swap
Solution with Current Report Output
Thermal Protection
The devices enter a thermal-shutdown mode in the event
of overheating caused by excessive power dissipation or
high ambient temperature. When the junction tem­perature
exceeds T_J = +150°C (typ), the internal thermal-protec-
tion circuitry turns off the internal power MOSFET. The
devices recover from thermal-shutdown mode once the
junction temperature drops by 20°C (typ).
IN to OUT Short-Circuit Protection
At startup, after all the input conditions are satisfied (UV,
OV, V_UVLO), the devices immediately check for an IN to
OUT short-circuit fault. If V_OUT is greater than 90% of
V_IN, the internal MOSFET cannot be turned on so FAULT
is asserted and the MAX15091A enters autoretry mode in
3.2s, while the MAX15091 latches off.
If V_OUT is lower than 90% of V_IN but greater than 50%
of V_IN, the internal MOSFET still cannot be turned on. No
fault is asserted and the MOSFET can turn on as soon as
V_OUT is lower than 50% of V_IN.
Applications Information
Setting the Undervoltage Threshold
The devices feature an independent on/off control (UV)
for the internal MOSFET. The devices operate with a 2.7V
to 18V input voltage range and have a default 2.5V (typ)
undervoltage-lockout threshold.
The internal MOSFET remains off as long as V_CC < 2.5V
or V_UV < V_{UV_TH}. The undervoltage-lockout threshold
is pro­grammable using a resistive divider from IN to UV,
OV, and GND (Figure 1). When V_CC is greater than 2.7V
and V_UV exceeds the 1.2V (typ) threshold, the internal
MOSFET turns on and goes into normal operation. Use
the following equation to calculate the resistor values for
the desired undervoltage threshold:
= R1


V_IN
V_{UV _TH}

- 1 × (R2 + R3 )
where V_IN is the desired turn-on voltage for the output
and V_{UV_TH} is 1.2V. R1 and (R2 + R3) create a resistive
divider from IN to UV. During normal operating conditions,
V_UV must remain above its 1.2V (typ) threshold. If V_UV
falls 100mV (V_{UV_HYS}) below the threshold, the internal
MOSFET turns off, disconnecting the load from the input.
Setting the Overvoltage Threshold
The devices also feature an independent overvoltage-
enable control (OV) for the internal MOSFET.
When V_OV exceeds the 1.2V (typ) threshold, the internal
MOSFET turns off.
The overvoltage-lockout threshold is pro­grammable using
a resistive divider from IN to UV, OV, and GND (Figure 1).
Use the following equation to calculate the resistor values
for the desired overvoltage threshold:
(= R1 + R2 )


V_IN
V_{OV _TH}

- 1 × R3
where V_IN is the desired turn-off voltage for the output
and V_{OV_TH} is 1.2V. R1 and (R2 + R3) create a resistive
divider from IN to OV. During normal operating conditions,
V_OV must remain below its 1.2V (typ) threshold. If V_OV
rises above the V_{OV_TH} threshold, the internal MOSFET
turns off and disconnects the load from the input.
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