F + 200

t

t

PERIOD

F + 200

t

t

PERIOD

or

UCC2895-EP

SCBS809F – DECEMBER 2005 – REVISED OCTOBER 2009

www.ti.com

Electrical Characteristics (continued)

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Oscillator

Frequency

473

500

527

kHz

Total variation

2.5

5

%

2.05

2.1

2.32

V

1.85

1.9

1.95

V

4.1

4.5

5

V

0

0.5

1

V

SYNC output pulse width

SYNC load = 3.9 k

Ω and 30 pF in parallel

85

135

ns

2.9

3

3.1

V

2.25

2.35

2.55

V

0

0.2

0.65

V

PWM Comparator

EAOUT to RAMP/input offset voltage

RAMP = 0 V, DELAB = DELCD = REF

0.72

0.85

1.05

V

Minimum phase shift

0

0.85

1.50

%

(OUTA to OUTC, OUTB to OUTD)

RAMP from 0 V to 2.5 V, EAOUT = 1.2 V,

RAMP to OUTC/OUTD delay

70

120

ns

RAMP bias current

–5

5

μA

RAMP sink current

12

19

mA

Current Sense

CS bias current

0 < CS< 2.5 V, 0 < ADS < 2.5 V

–4.5

20

μA

Peak current threshold

1.9

2

2.1

V

Overcurrent threshold

2.4

2.5

2.6

V

CS to output delay

CS from 0 to 2.3 V, DELAB = DELCD = REF

75

110

ns

Soft Start/Shutdown

Soft-start source current

SS/DISB = 3 V, CS = 1.9 V

–40

–35

–30

μA

Soft-start sink current

SS/DISB = 3 V, CS = 2.6 V

325

350

375

μA

Soft-start/disable comparator threshold

0.44

0.5

0.56

V

Delay Set

ADS = CS = 0 V

0.45

0.5

0.55

V

DELAB/DELCD output voltage

ADS = 0 V, CS = 2 V

1.9

2

2.1

V

Output delay

450

525

600

ns

ADS bias current

0 V < ADS < 2.5 V, 0 V < CS < 2.5 V

–20

20

μA

(2)

Minimum phase shift is defined as:

where:

(3)

Output delay is measured between OUTA/OUTB or OUTC/OUTD. Output delay is shown in Figure 1 and Figure 2 , where:

(4)

Specified by design. Not production tested.

6

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