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MP5402M Datasheet(PDF) 12 Page - Monolithic Power Systems
MPS [Monolithic Power Systems]
MP5402M Datasheet(HTML) 12 Page - Monolithic Power Systems
/ 17 page
MP5402M ? STEP-DOWN CONVERTER WITH SMART DUAL USB CHARGING PORTS
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
alleviates thermal issues, and protects the
regulator. The MP5402M exits hiccup mode
once the over-current condition is removed.
Buck Output Over-Voltage Protection (OVP)
protection (OVP). If the output is higher than 6V,
the high-side switch stops switching, and the
low-side switch turns on to discharge the output
voltage until the output decreases to 5.75V. The
chip then returns to normal operation. If the
output over voltage cannot be discharged to
5.75V, the low-side switch turns off after the
inductor current reaches a negative current limit.
The low-side switch turns on again when the
next clock cycle begins.
Floating Driver and Bootstrap Charging
An external bootstrap capacitor powers the
floating power MOSFET driver. This floating
driver has its own UVLO protection. The
UVLO?s rising threshold is 2.2V with a
hysteresis of 150mV. The bootstrap capacitor
voltage is regulated internally by V
M1, C4, L1, and C2 (see Figure 3). If V
exceeds 5V, U1 regulates M1 to maintain a 5V
BST voltage across C4.
Figure 3: Internal Bootstrap Charging Circuit
Start-Up and Shutdown
If both V
and EN exceed their respective
thresholds, the chip is enabled. The reference
block starts first, generating a stable reference
voltage and currents, and then the internal
regulator is enabled. The regulator provides a
stable supply for the remaining circuitries.
Several events can shut down the chip: EN low,
low, and thermal shutdown. In shutdown, the
signaling path is blocked to avoid any fault
triggering, and the COMP voltage and the
internal supply rail are pulled down. The floating
driver is not subject to this shutdown command.
Buck Output Discharge
The buck portion of the device involves a
discharge function that provides a resistive
discharge path for the external output capacitor.
The function is active when the part is disabled
(input voltage is under UVLO, EN off) and is
done in a very limited time. After VCC
discharges below 1V, the buck output discharge
USB CURRENT-LIMIT SWITCH
The MP5402M integrates two USB current-limit
switches. It provides a built-in soft-start circuitry,
which controls the rising slew rate of the output
voltage to limit the inrush current and voltage
When the load current reaches the current-limit
threshold (2.75A, typically), the USB power
MOSFET switches into foldback current-limit
mode, 70% of the current limit (see Figure 4). If
the over-current limit condition lasts for more
than 3ms, the USB channel enters hiccup mode
with a 3ms on time and a 8.5s off time.
Figure 4: Over-Current Limit
or EN start-up, ensure that the CC
load current does not exceed 70% of the current
limit to avoid triggering a foldback current limit
and start-up failure.
Output Line Drop Compensation
The MP5402M can compensate an output-
voltage drop?such as high impedance caused
by a long trace?to keep a fairly constant 5V
The internal comparator compares the current-
sense output voltage of the two current-limit
switches and uses the larger current-sense
output voltage to compensate the line drop
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