NX5P2553_15 datasheet(4/24 Pages) PHILIPS

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NX5P2553

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Product data sheet

Rev. 1 — 6 July 2015

4 of 24

NXP Semiconductors

NX5P2553

Precision adjustable current-limited power switch

8.1 EN input

When EN is set to LOW, the N-channel MOSFET is disabled and the device enters a

low-power mode. In low-power mode, all protection circuits are disabled and the FAULT

output is set to high-impedance state. When EN is set to HIGH, all protection circuits are

enabled. If no fault conditions exist, the N-channel MOSFET is enabled.

8.2 UnderVoltage LockOut (UVLO)

The UVLO circuit is active until VIN > 2.35 V. It disables the N-channel MOSFET and

switches the device back to low-power mode. It occurs irrespective of the logic level on

the EN pin. Once VIN > 2.35 V, the EN pin controls the N-channel MOSFET state. The

UVLO circuit remains active in low-power mode.

8.3 ILIM

The OverCurrent Protection (OCP) circuit trigger value Iocp is set using an external

resistor connected to the ILIM pin as shown in Figure 8. If EN is set to HIGH and the ILIM

pin is grounded, the N-channel MOSFET is disabled and the FAULT output is set to LOW.

8.4 OverCurrent Protection (OCP)

Three possible overcurrent conditions can occur. They are:

• Overcurrent at start-up, ISW > Iocp when enabling the N-channel MOSFET

• Overcurrent when enabled, ISW > Iocp when the N-channel MOSFET is enabled

• Short-circuit when enabled, ISW > 4  Iocp (typical)

8.4.1 Overcurrent at start-up

If the device senses a short or overcurrent while enabling the N-channel MOSFET, OCP is

triggered. It limits the output current to Iocp and after the deglitch time sets the FAULT

output to LOW, as shown in Figure 22. Increased power dissipation combined with the

OTP may lead to temperature cycling.

8.4.2 Overcurrent when enabled

When enabled, if the device senses ISW > Iocp, the OCP is triggered. It limits the output

current to Iocp and after the deglitch time sets the FAULT output to LOW. Limiting the

output current reduces VO(VOUT), as shown in Figure 20 and Figure 21. Increased power

dissipation combined with the OTP may lead to temperature cycling.

8.4.3 Short-circuit when enabled

When enabled, if the device senses ISW > 4  Iocp, a short-circuit is detected. The device

disables the N-channel MOSFET immediately. It then enables the N-channel MOSFET,

output current is limited to Iocp and after the deglitch time, the FAULT output is set to LOW

as shown in Figure 16 to Figure 19. Increased power dissipation combined with the OTP

may lead to temperature cycling.

8.5 Reverse-Voltage Protection (RVP)

If VOUT exceeds VIN by 140 mV for the deglitch time, RVP protects the device by

disabling the N-channel MOSFET. When the reverse voltage condition is removed for the

deglitch time, the N-channel MOSFET is enabled as shown in Figure 14 and Figure 15.

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