0

20

40

60

80

100

120

140

160

180

200

-50

-25

0

25

50

75

100

125

150

T -JunctionTemperature-°C

J

V

=3.3V

IN

88

90

92

94

96

98

100

102

104

106

108

110

VsenseRising,V

=3.3V

IN

VsenseRising

VsenseFalling

VsenseFalling

-50

-25

0

25

50

75

100

125

150

T -JunctionTemperature-°C

J

300

310

320

330

340

350

360

370

380

390

400

3

3.5

4

4.5

5

5.5

6

V

-InputVoltage-V

IN

T =25°C

J

TPS54218

SLVS974A – SEPTEMBER 2009 – REVISED AUGUST 2012

www.ti.com

TYPICAL CHARACTERISTICS CURVES (continued)

SUPPLY CURRENT vs INPUT VOLTAGE

PWRGD THRESHOLD vs TEMPERATURE

Figure 19.

Figure 20.

PWRGD ON RESISTANCE vs TEMPERATURE

Figure 21.

OVERVIEW

The TPS54218 is a 6-V, 2 A, synchronous step-down (buck) converter with two integrated n-channel MOSFETs.

To improve performance during line and load transients the device implements a constant frequency, peak

current mode control which reduces output capacitance and simplifies external frequency compensation design.

The wide switching frequency of 200 kHz to 2000 kHz allows for efficiency and size optimization when selecting

the output filter components. The switching frequency is adjusted using a resistor to ground on the RT/CLK pin.

The device has an internal phase lock loop (PLL) on the RT/CLK pin that is used to synchronize the power

switch turn on to a falling edge of an external system clock.

The TPS54218 has a typical default start up voltage of 2.6 V. The EN pin has an internal pull-up current source

that can be used to adjust the input voltage under voltage lockout (UVLO) with two external resistors. In addition,

the pull up current provides a default condition when the EN pin is floating for the device to operate. The total

operating current for the TPS54218 is 350

μA when not switching and under no load. When the device is

disabled, the supply current is less than 5

μA.

The integrated 30 m

Ω MOSFETs allow for high efficiency power supply designs with continuous output currents

up to 2 amperes.

10

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