參數(shù)資料
型號: TPS54418RTER
廠商: TEXAS INSTRUMENTS INC
元件分類: 穩(wěn)壓器
英文描述: 6.4 A SWITCHING REGULATOR, 2000 kHz SWITCHING FREQ-MAX, PQCC16
封裝: 3 X 3 MM, GREEN, PLASTIC, WQFN-16
文件頁數(shù): 15/35頁
文件大?。?/td> 1356K
代理商: TPS54418RTER
-
×
-
START
STOP
6
0.944 V
V
R1 =
2.59
10
-
×
-
+
×
6
STOP
1.18 R1
R2 =
V
1.18
R1 3.2
10
-
Vref
R7 =
R6
Vo
Vref
(
)
(
)
(
)
(
)
(
)
(
)
Voutmin
Ontimemin
Fsmax
Vinmax
Ioutmin
2
RDS
Ioutmin
RL
RDS
=
-
-
+
SLVS946A – MAY 2009 – REVISED MAY 2010
www.ti.com
BOOTSTRAP CAPACITOR SELECTION
A 0.1 mF ceramic capacitor must be connected between the BOOT to PH pin for proper operation. It is
recommended to use a ceramic capacitor with X5R or better grade dielectric. The capacitor should have 10 V or
higher voltage rating.
UNDER VOLTAGE LOCK OUT SET POINT
The Under Voltage Lock Out (UVLO) can be adjusted using an external voltage divider on the EN pin of the
TPS54418. The UVLO has two thresholds, one for power up when the input voltage is rising and one for power
down or brown outs when the input voltage is falling. For the example design, the supply should turn on and start
switching once the input voltage increases above 3.1 V (VSTART). After the regulator starts switching, it should
continue to do so until the input voltage falls below 2.8 V (VSTOP).
The programmable UVLO and enable voltages are set using a resistor divider between Vin and ground to the EN
pin. Equation 29 and Equation 30 can be used to calculate the resistance values necessary. From Equation 29
and Equation 30, a 48.7 k
between Vin and EN and a 32.4 k between EN and ground are required to produce
the 3.1 and 2.8 volt start and stop voltages.
(29)
(30)
OUTPUT VOLTAGE AND FEEDBACK RESISTORS SELECTION
For the example design, 100 k
was selected for R6. Using Equation 31, R7 is calculated as 80 k. The nearest
standard 1% resistor is 80.5 k
.
(31)
Due to the internal design of the TPS54418, there is a minimum output voltage limit for any given input voltage.
The output voltage can never be lower than the internal vlotage reference of 0.8 V. Above 0.8 V, the output
voltage may be limited by the minimum controllable on time. The minimum output voltage in this case is given by
Where:
Voutmin = minimum achieveable output voltage
Ontimemin = minimum contollable on-time (60 ns typical. 110 nsec no load)
Fsmax = maximum switching frequency including tolerance
Vinmax = maximum input voltage
Ioutmin = minimum load current
RDS = minimum high side MOSFET on resistance (30 - 44 m
)
RL = series resistance of output inductor
(32)
There is also a maximum acheivable output voltage which is limited by the minimum off time. The maximum
output voltage is given by Equation 33
22
Copyright 2009–2010, Texas Instruments Incorporated
Product Folder Link(s): TPS54418
相關PDF資料
PDF描述
TPS54426PWP 7.5 A SWITCHING REGULATOR, 700 kHz SWITCHING FREQ-MAX, PDSO14
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TPS54612MPWPREP 12 A SWITCHING REGULATOR, 700 kHz SWITCHING FREQ-MAX, PDSO28
相關代理商/技術參數(shù)
參數(shù)描述
TPS54418RTERG4 制造商:Texas Instruments 功能描述:
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TPS54425_10 制造商:TI 制造商全稱:Texas Instruments 功能描述:4-A OUTPUT SINGLE SYNCHRONOUS STEP DOWN SWITCHER WITH INTEGRATED FET ( SWIFT?)