LM5025B

SNVS354B – JULY 2005 – REVISED MARCH 2013

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Electrical Characteristics

(1) (continued)

Specifications with standard typeface are for TJ = 25°C, and those with boldface type apply over full Operating Junction

Temperature range. VIN = 48V, VCC = 10V, RT = 26.7kΩ, RSET = 27.4kΩ) unless otherwise stated

Symbol

Parameter

Conditions

Min

Typ

Max

Units

Current Limit

CS1 Prop

CS1 Delay to Output

CS1 Step from 0 to 0.4V

40

ns

Time to onset of OUT

Transition (90%)

Cgate = 0

CS2 Prop

CS2 Delay to Output

CS2 Step from 0 to 0.6V

50

ns

Time to onset of OUT

Transition (90%)

Cgate = 0

Cycle by Cycle Threshold

0.22

0.25

0.28

V

Voltage (CS1)

Cycle Skip Threshold

Resets SS capacitor; auto

0.45

0.5

0.55

V

Voltage (CS2)

restart

Leading Edge Blanking

50

ns

Time (CS1)

CS1 Sink Impedance

CS1 = 0.2V

30

50

Ω

(clocked)

CS1 Sink Impedance

CS1 = 0.3V

55

95

Ω

(Post Fault Discharge)

CS2 Sink Impedance

CS2 = 0.6V

55

95

Ω

(Post Fault Discharge)

CS1 and CS2 Leakage

CS = CS Threshold - 100mV

1

µA

Current

Soft-Start

Soft-start Current Source

17

22

27

µA

Normal

Soft-start Current Source

0.5

1

1.5

µA

following a CS2 event

Oscillator

Frequency1

TA = 25°C

180

220

200

kHz

TJ = Tlow to Thigh

175

225

Frequency2

RT = 13.3 k

Ω

TJ = Tlow to Thigh

360

400

440

kHz

TJ = 0°C to 125°C

364

436

Sync threshold

2

V

Min Sync Pulse Width

100

ns

Sync Frequency Range

160

kHz

PWM Comparator

Delay to Output

COMP step 5V to 0V

40

ns

Time to onset of OUT_A

transition low

Maximum Duty Cycle 1

Measured at OUT_A

73

%

Maximum Duty Cycle 2

Measured at OUT_A;

66

71

75

RT = 13.3K

COMP to PWM Offset

0.75

1

1.15

V

COMP Input Current

COMP = 4V, SS open

50

80

µA

Volt x Second Clamp

Ramp Clamp Level

Delta RAMP measured from

2.4

2.5

2.6

V

onset of OUT_A to Ramp peak.

COMP = 5V

6

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