PTH08T255W datasheet(4/35 Pages) TI1

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ELECTRICAL CHARACTERISTICS

PTH08T255W

SLTS290 – NOVEMBER 2008 ........................................................................................................................................................................................... www.ti.com

PTH08T255W

TA = 25°C, VI = 12 V, VO = 3.3 V, CI = 1000 µF, CO = 1000 µF, and IO = IO max (unless otherwise stated)

PARAMETER

TEST CONDITIONS

PTH08T255W

UNIT

MIN

TYP

MAX

25°C, natural convection

Output current

Over VO range

60°C, 200 LFM

Input voltage range

Over IO and VO range

8.0

VOADJ

Output voltage adjust range

Over IO range

3.0

5.25

Set-point voltage tolerance

±0.5

±1 (1)

%Vo

Temperature variation

–40°C < TA < 85°C

±0.3

%Vo

Line regulaltion

Over VI range

±5

Load regulation

Over IO range

±5

Total output variation

Includes set-point, line, load, –40°C

≤ TA ≤ 85°C

±1.5 (1)

%Vo

RSET = 1.36 kΩ, VO = 5.0 V

95%

Efficiency

IO = 30 A

RSET = 34.5 kΩ, VO = 3.3 V

94%

VO Ripple (peak-to-peak)

20-MHz bandwidth

mVPP

ILIM

Overcurrent threshold

Reset, followed by auto-recovery

ttr

Recovery time

200

µs

w/o TurboTrans

CO= 1000 µF, TypeC

ΔVtr

VO over/undershoot

135

2.5 A/µs load step

Transient response

50 to 100% IOmax

ttrTT

w/ TurboTrans

Recovery time

400

µs

CO= 5000 µF, TypeC

ΔVtrTT

VO over/undershoot

RTT = short

IIL

Track input current (pin 20)

Pin to GND

–130(2)

µA

dVtrack/dt

Track slew rate capability

CO ≤ CO (max)

V/ms

VI increasing, RUVLO = OPEN

7.2

8.0

Adjustable Under-voltage lockout

UVLOADJ

VI decreasing, RUVLO = OPEN

6.7

(pin 21)

Hysteresis

0.5

Input high voltage (VIH)

Open(3)

Inhibit control (pin 21)

Input low voltage (VIL)

-0.2

0.6

Input low current (IIL ), Pin 21 to GND

-125

µA

Iin

Input standby current

Inhibit (pin 21) to GND, Track (pin 20) open

f s

Switching frequency

Over VI and IO ranges, SmartSync (pin 22) to GND

600 (4)

kHz

fSYNC

Synchronization frequency applied to pin 22

240 (4)

400 (4)

kHz

VSYNCH

SYNC High-Level Input Voltage

2.0

5.5

Synchronization (SYNC)

control (pin 22)

VSYNCL

SYNC Low-Level Input Voltage

0.8

tSYNC

SYNC Minimum Pulse Width

200

nSec

Nonceramic

1000 (5)

External input capacitance

µF

Ceramic

(1)

The set-point voltage tolerance is affected by the tolerance and stability of RSET. The stated limit is unconditionally met if RSET has a

tolerance of 1% with 100 ppm/C or better temperature stability.

(2)

A low-leakage (<100 nA), open-drain device, such as MOSFET or voltage supervisor IC, is recommended to control pin 20. When using

this feature, a 100k

Ω pull-up resistor to VI is required. If unused, this pin must be directly connected to VI. See the Auto-Track section of

the datasheet for more information.

(3)

Do not place an external pull-up on this pin. If it is left open-circuit, the module operates when input power is applied. A small,

low-leakage (<100 nA) MOSFET is recommended for control. For additional information, see the On/Off Inhibit section of the datasheet.

(4)

The PTH08T255W is a two-phase power module. Each phase switches at 300kHz typical, 180° out of phase from one another. The

over-all switching frequency is 600 kHz typical. SmartSync controls the frequency of an individual phase.

(5)

A 1000 µF electrolytic input capacitor is required for proper operation. The input capacitor must be rated for a minimum of 750 mA rms

of ripple current.

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