Rainbow Electronics MAX5971А - Manual (Page 12)

12 _____________________________________________________________________________________
MAX5971A
Single-Port, 40W, IEEE 802.3af/802.3at PSE
Controller with Integrated MOSFET
Pin Description (continued)
PIN NAME FUNCTION
13 LEGACY
Legacy Detection Logic Input. Referenced to V EE . LEGACY is internally pulled up to the digital
supply. Leave unconnected to activate the legacy PD detection. Force low to disable this function.
The LEGACY logic level latches after the device is powered up or after a reset condition.
14 EN
Enable Input. Referenced to V EE . EN is internally pulled up to the digital supply. Leave uncon-
nected to enable the device. Force low for at least 40Fs to reset the device. The MIDSPAN, OSC,
and LEGACY states latch-in when the reset condition is removed (low-to-high transition).
16, 18, 20,
22, 24, 28
N.C. No Connection. Not internally connected. Leave N.C. unconnected.
17 LED
LED Indicator Open-Drain Output. Referenced to V EE . LED can sink 10mA and can drive an exter-
nal LED directly. Blinking functionality is provided to signal different conditions (see the PWM and
LED Signals section). Connect LED to AGND externally (see Figures 6 and 7) or to an external
supply (if available) through a series resistance.
19 OSC
AC-Disconnect Triangular Wave Output. Bypass with a 100nF (Q10% tolerance) external capacitor
to V
EE to enable the AC disconnect function. Connect OSC to V EE to disable the AC disconnect
function and to activate the DC disconnect function. The OSC state latches after the device is
powered up or after a reset condition.
21 AGND High-Side Supply Input
23 DET
Detection/Classification Voltage Output. DET is used to set the detection mark event and clas-
sification probe voltages and for the AC current sensing when using the AC disconnect function.
To use the AC disconnect function, place a 1kI and 0.47FF RC series in parallel with the external
protection diode to OUTP (see Figure 7).
25 OUTP
Port Pullup Output. OUTP is used to pull up the port voltage to AGND when needed. If AC discon-
nect is used, connect OUTP to the anode of the AC-blocking diode. If AC disconnect is not used,
connect OUTP to OUT (see Figures 6 and 8). Bypass OUTP to AGND with a 100V, 0.1FF ceramic
capacitor.
26, 27 OUT
Integrated MOSFET Output. If DC disconnect is used, connect the port output to OUT (see Figures
6 and 8). If the AC disconnect function is used, connect OUT to the cathode of the AC-blocking
diode (see Figure 7).
— EP Exposed Pad. Connect EP to V EE externally. See the Layout Procedure section for details.