LTC4259A datasheet(4/32 Pages) LINER

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LTC4259A

4259Af

Note 7: The LTC4259A is designed to maintain a port voltage of –46.6V to

–57V and the VEE supply voltage range accounts for the drop across the

diode, MOSFET and sense resistor.

Note 8: VEE supply current, while classifying a short, is measured

indirectly by measuring the DETECT

n pin current while classifying a short.

Note 9: The LTC4259A implements overload current detection per IEEE

802.3af. The minimum overload current (ICUT) is dependent on port

voltage; ICUT_MIN = 15.4W/VPORT_MIN. An IEEE compliant system using the

LTC4259A should maintain port voltage above –46.6V.

Note 10: Unless otherwise specified, AC disconnect specifications require

the following conditions: the DETECT pin is connected to the port as

shown in Figure 1, a valid sine wave is applied to OSCIN, the OSCFAIL bit

is cleared and the AC Disconnect Enable bits are set.

Note 11: Guaranteed by design, not subject to test.

Note 12: Values measured at VILD and VIHD.

Note 13: If fault occurs during an I2C transaction, the INT pin will not be

pulled down until a stop condition is present on the I2C bus.

Note 1: Absolute Maximum Ratings are those values beyond which the life

of the device may be impaired.

Note 2: DGND and AGND should be tied together in normal operation.

Note 3: An internal clamp limits the GATE pins to a minimum of 12V above

VEE. Driving this pin beyond the clamp may damage the part.

Note 4: When a port powers on or off, the transient voltage on the port

couples through CDET (Figure 16). The LTC4259A contains internal

protection circuitry to withstand transient currents of up to 80mA for 5ms.

As long as the absolute value of the current remains below 80mA, the

LTC4259A will keep the voltage at the DETECT

n pin within the absolute

maximum voltage range. A properly sized RDET should limit the current to

less than 60mA.

Note 5: This IC includes overtemperature protection that is intended to

protect the device during momentary overload conditions. Junction

temperature will exceed 125

°C when overtemperature protection is active.

Continuous operation above the specified maximum operating junction

temperature may impair device reliability.

Note 6: All currents into device pins are positive; all currents out of device

pins are negative. All voltages are referenced to ground (AGND and DGND)

unless otherwise specified.

ELECTRICAL CHARACTERISTICS The q denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. AGND = DGND = 0V, VDD = 3.3V, VEE = –48V unless otherwise noted

(Note 6).

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

tICUT

Maximum Current Limit Duration After

tICUT1 = 0, tICUT0 = 0 (Figure 3)

Port Start-Up

tICUT1 = 0, tICUT0 = 1

tICUT1 = 1, tICUT0 = 0

100

120

140

tICUT1 = 1, tICUT0 = 1

200

240

280

DCCLMAX

Maximum Current Limit Duty Cycle

Reg16h = 00h

5.8

6.3

6.7

tDIS

Disconnect Delay

tDIS1 = 0, tDIS0 = 0 (Figures 4, 5)

300

360

400

tDIS1 = 0, tDIS0 = 1

100

tDIS1 = 1, tDIS0 = 0

150

180

200

tDIS1 = 1, tDIS0 = 1

600

720

800

tVMIN

DC Disconnect Minimum Pulse

VSENSEn – VEE > 5mV, VOUTn = –48V (Figure 4)

0.02

Width Sensitivity

(Note 11)

I2C Timing

fSCLK

Clock Frequency

(Note 11)

400

kHz

Bus Free Time

Figure 6 (Notes 11, 12)

1.3

µs

Start Hold Time

Figure 6 (Notes 11, 12)

600

SCL Low Time

Figure 6 (Notes 11, 12)

1.3

µs

SCL High Time

Figure 6 (Notes 11, 12)

600

Data Hold Time

Figure 6 (Notes 11, 12)

150

Data Set-Up Time

Figure 6 (Notes 11, 12)

200

Start Set-Up Time

Figure 6 (Notes 11, 12)

600

Stop Set-Up Time

Figure 6 (Notes 11, 12)

600

SCL, SDAIN Rise Time

Figure 6 (Notes 11, 12)

300

SCL, SDAIN Fall Time

Figure 6 (Notes 11, 12)

150

tFLTINT

Fault Present to INT Pin Low

(Notes 11, 12, 13)

150

tSTOPINT

Stop Condition to INT Pin Low

(Notes 11, 12, 13)

200

tARAINT

ARA to INT Pin High Time

(Notes 11, 12)

300

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