MP5016 – 2.7 - 15V, 0.7 - 5A, PROGRAMMABLE, CURRENT-LIMITED SWITCH
Short-Circuit Protection (SCP)
A 100pF capacitor is required on GATE if it is not
connected to the external MOSFET.
If the load current increases rapidly due to a
short-circuit event, the current may exceed the
current-limit threshold before the control loop
can respond. If the current reaches the 8A
secondary current limit level, a fast turn-off circuit
activates to turn off the power MOSFET. This
can help limit the peak current through the switch,
keeping the input voltage from dropping too
much. The total short-circuit response time is
about 1µs. After the MOSFET has switched off,
the part restarts. During the restart process, if the
short still exists, the MP5016 regulates the gate
voltage to hold the current at a normal current
limit level. The IC enters hiccup mode with 2ms
of on time and 700ms of off time.
Output Discharge
The MP5016 involves a discharge function that
provides a resistive discharge path for the
external output capacitor. The function is active
when the part is disabled (VIN UVLO, EN
shutdown) and is done in a very limited amount
of time. When using the external reverse-current
block MOSFET, the output discharge path is
blocked by the reverse current block MOSFET.
Therefore, the output cannot be discharged
when the reverse-current block MOSFET is used.
Enable (EN)
The MP5016 is enabled when EN is high. The
MP5016 is disabled when EN is low. Floating EN
shuts down the MP5016 because there is an
internal 2.2MΩ resistor pulling EN down to
ground. For automatic start-up, connect a pull-up
resistor from VCC to EN.
To prevent safe operating area (SOA) damage
during
a
high input voltage short-circuit
protection (SCP) condition, the IC current limit
folds back when the power MOSFET VDS voltage
is above the typical 11V and the junction
temperature is over 110°C.
EN is clamped internally using a 5.5V Zener
diode (see Figure 2). Connecting the EN input
through a pull-up resistor to VCC limits the EN
input current below 100μA to prevent damage to
the Zener diode. For example, when connecting
a 300kΩ pull-up resistor to 15V VCC, IZener = (15V
- 5.5V) / 300kΩ - 5.5V / 2.2MΩ = 29µA.
Reverse Blocking MOSFET Driver
The MP5016 has a GATE pin to provide an
external N-channel MOSFET gate drive signal
for reverse-current protection (RCP). Three
events can pull down the GATE voltage: VIN
below the under-voltage lockout (UVLO), the
enable (EN) voltage below the low-level
threshold, or thermal shutdown. If any of these
conditions occur, GATE sinks the current from
the gate of the external MOSFET to initiate a fast
turn-off.
1kΩ
EN
EN
Logic
2.2MΩ
5.5V
GND
For 3.3V low input voltage applications, choose
an external reverse blocking MOSFET with a
small gate threshold voltage (VGSth < 1.6V) to
reduce the voltage drop caused by the reverse-
blocking MOSFET.
Figure 2: Zener Diode between EN and GND
When using a pull-up resistor to set the power-
on threshold, avoid using a pull-up resistor that
is too small to increase the operational quiescent
current.
Setting an appropriate OVP threshold also can
protect the reverse voltage (from the output to
the input) when using an external N-channel
MOSFET. When VOUT rises too high during
normal operation, the MP5016 SOURCE voltage
is higher than the OVP threshold. In this case,
the GATE voltage is regulated to maintain the
SOURCE clamped at the OVP threshold. This
action protects the reverse current from the high
VOUT to the low VIN.
Thermal Shutdown – Auto-Retry
Thermal shutdown prevents the chip from
operating at exceedingly high temperatures.
When the silicon die temperature exceeds 175°C,
the entire chip shuts down, and EN reports a fail
mode. When the temperature drops below its
lower threshold (typically 125°C), the chip is
enabled again after a 700ms delay, typically.
MP5016 Rev.1.0
6/20/2017
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