V
I
− Input Voltage − V
5
6
7
8
9
10
11
12
13
1 5 9 13 17
T
J
= 150°C
IcI − Current Limit Threshold − A
T
J
= 25°C
T
J
= −40°C
T
J
− Junction Temperature − °C
70
80
90
100
110
120
−50 −25 0 25 50 75 100 125 150
VIN = 12 V
IOUT = 2A
Minimum Controllable On Time − ns
T
J
− Junction Temperature − °C
2.0
2.1
2.2
−50 −25 0 25 50 75 100 125 150
BOO-PH UVLO Threshold − V
T
J
− Junction Temperature − Deg
3.0
4.0
5.0
6.0
−50 −25 0 25 50 75 100 125 150
RT = 100 kΩ
VIN =12 V
IOUT = 2 A
Dmin − Minimum Controllable Duty Ratio − %
OVERVIEW
TPS54620
www.ti.com
........................................................................................................................................................................................................ SLVS949 – MAY 2009
TYPICAL CHARACTERISTICS (continued)
HIGH-SIDE CURRENT LIMIT THRESHOLD vs INPUT
VOLTAGE MINIMUM CONTROLLABLE ON TIME vs TEMPERATURE
Figure 13. Figure 14.
MINIMUM CONTROLLABLE DUTY RATIO vs JUNCTION
TEMPERATURE BOOT-PH UVLO THRESHOLD vs TEMPERATURE
Figure 15. Figure 16.
The device is a 17-V, 6-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 also simplifies external frequency compensation. The wide switching frequency of 200 kHz to
1600 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 also has an internal phase lock
loop (PLL) controlled by the RT/CLK pin that can be used to synchronize the switching cycle to the falling edge
of an external system clock.
The device has been designed for safe monotonic startup into pre-biased loads. The default start up is when VIN
is typically 4.0V. 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 EN pin can be floating for the device to
operate with the internal pull up current. The total operating current for the device is approximately 600 µ A when
not switching and under no load. When the device is disabled, the supply current is typically less than 2 µ A.
The integrated MOSFETs allow for high efficiency power supply designs with continuous output currents up to 6
amperes. The MOSFETs have been sized to optimize efficiency for lower duty cycle applications.
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