MAX5941BCSE(2003) データシートの表示（PDF） - Maxim Integrated

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MAX5941BCSE
(Rev.:2003)

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices

Maxim Integrated 

IEEE 802.3af-Compliant Power-Over-Ethernet

Interface/PWM Controller for Power Devices

4.7nF

250VAC

RDISC

25.5kΩ

1N4148

VIN

(30V TO 72V)

6 NT

14 NR

CMHD2003

CDD

47µF

VDD

GND V+

CIN

3 × 0.47µF

NP

14

MAX5941B

UVLO

NDRV

M1

IRF640N

RCL

GATE

100Ω

CS

PGOOD

RCL

SS_SHDN

V-

CSS

OUT

0.1µF

VCC

PGOOD

4.75kΩ

20Ω

NS

5

RSENSE

100mΩ

CCC

10µF

SBL204OCT

L1

4.7µH

COUT

3 × 560µF

1nF

220Ω

VEE

OPTO

OPTOCOUPLER

R1

25.5kΩ

3kΩ

0.1µF

VOUT

5V/10A

0.1µF

240kΩ

TLV431

R2

8.25kΩ

Figure 5. Forward Converter

to 2.4V, the internal voltage reference. Pull VSS_SHDN

below 0.25V to disable the controller.

Undervoltage lockout shuts down the controller when

VCC is less than 6.6V. The regulators for V+ and the ref-

erence remain on during shutdown.

Current-Sense Comparator

The current-sense (CS) comparator and its associated

logic limit the peak current through the MOSFET.

Current is sensed at CS as a voltage across a sense

resistor between the source of the MOSFET and GND.

To reduce switching noise, connect CS to the external

MOSFET source through a 100Ω resistor or an RC low-

pass filter (Figures 5, 6). Select the current-sense resis-

tor, RSENSE, according to the following equation:

RSENSE = 0.465V /ILimPrimary

where ILimPrimary is the maximum peak primary-side

current.

When VCS > 465mV, the power MOSFET switches off.

The propagation delay from the time the switch current

reaches the trip level to the driver turn-off time is 170ns.

16 ______________________________________________________________________________________

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