TPS54620 Datasheet, PDF (9/39 Pages) Texas Instruments – 17V Input, 6A Output, Synchronous Step Down Switcher With Integrated FET in 3.5mm x 3.5mm Package(SWIFT™)

TPS54620
www.ti.com ........................................................................................................................................................................................................ SLVS949 – MAY 2009
TYPICAL CHARACTERISTICS (continued)
HIGH-SIDE CURRENT LIMIT THRESHOLD vs INPUT
VOLTAGE
13
12
11
10
9
T_J = −40°C _{TJ = 25°C}
T_J = 150°C
8
7
6
5
1
5
9
13
17
V_I − Input Voltage − V
Figure 13.
MINIMUM CONTROLLABLE DUTY RATIO vs JUNCTION
TEMPERATURE
6.0
MINIMUM CONTROLLABLE ON TIME vs TEMPERATURE
120
VIN = 12 V
IOUT = 2A
110
100
90
80
70
−50 −25
0 25 50 75 100 125 150
T_J − Junction Temperature − °C
Figure 14.
BOOT-PH UVLO THRESHOLD vs TEMPERATURE
2.2
5.0
2.1
4.0
3.0
−50 −25
RT = 100 kΩ
VIN =12 V
IOUT = 2 A
0 25 50 75 100 125 150
T_J − Junction Temperature − Deg
Figure 15.
2.0
−50 −25
0 25 50 75 100 125 150
T_J − Junction Temperature − °C
Figure 16.
OVERVIEW
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 600µA when
not switching and under no load. When the device is disabled, the supply current is typically less than 2µA.
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.
Copyright © 2009, Texas Instruments Incorporated
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