PM8800ATR STMicroelectronics, PM8800ATR Datasheet - Page 28

• Manufacturer Part Number: PM8800ATR
• Description: IC POE-PD PWM CTLR 16-HTSSOP
• Manufacturer: STMicroelectronics

Specifications of PM8800ATR

• Applications: Power Over Ethernet (PoE)
• Interface: IEEE 802.3af
• Voltage - Supply: 10 V
• Package / Case: 16-TSSOP Exposed Pad, 16-eTSSOP, 16-HTSSOP
• Mounting Type: Surface Mount
• For Use With: 497-6366 - BOARD EVAL FOR PM8800A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6897-2; PM8800ATR

PWM section
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Figure 18. Internal short circuit
Ch1 = 5 Vout, Ch2 = SoftStart, Ch4= I input
Leading edge blanking
The sense current waveform often observes large spikes on the leading edge. This is due to
rectifier recovery and/or interwinding capacitance in the power transformer. If not
attenuated, this transient can prematurely terminate the output pulse. A simple RC filter -
whose time constant is approximately equal to the spike duration - is usually adequate to
suppress this spike.
An internal blanking time has been anyway integrated in order to prevent false overcurrent
detection to terminate the PWM waveform. This is done by a masking logic, active for
duration of 70 ns after the turn-on time of the primary side MOSFET.
Thermal protection
PM8800A has a two level thermal protection referred to the internal junction temperature.
First limit is set to 130 °C and limits the current into the hot-swap MOSFET to 140 mA every
time the voltage difference between VSS and GND is higher than 3 V.
The second limit is set to 160 °C and is always active. When this threshold is overtaken, the
hot-swap is opened and the PWM controller is switched-off.
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PM8800A