TPS54218_12 Datasheet, PDF (10/37 Pages) Texas Instruments – 2.95 V to 6 V Input, 2 A Output, 2MHz, Synchronous Step Down

TPS54218
SLVS974A – SEPTEMBER 2009 – REVISED AUGUST 2012
www.ti.com
TYPICAL CHARACTERISTICS CURVES (continued)
SUPPLY CURRENT vs INPUT VOLTAGE
400
T_J = 25°C
390
PWRGD THRESHOLD vs TEMPERATURE
110
108
Vsense Rising, V_IN = 3.3 V
380
106
Vsense Falling
370
104
102
360
100
350
98
340
96
330
94
Vsense Rising
320
92
310
90
Vsense Falling
300
3
3.5
4
4.5
5
5.5
6
V_IN - Input Voltage - V
88
-50 -25
0
25
50
75 100 125 150
T_J - Junction Temperature - °C
Figure 19.
Figure 20.
PWRGD ON RESISTANCE vs TEMPERATURE
200
180 V_IN = 3.3 V
160
140
120
100
80
60
40
20
0
-50 -25
0
25
50
75 100
T_J - Junction Temperature - °C
Figure 21.
125 150
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 mΩ MOSFETs allow for high efficiency power supply designs with continuous output currents
up to 2 amperes.
10
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