參數(shù)資料
型號(hào)： TPS54429ERSAT
廠商： TEXAS INSTRUMENTS INC
元件分類(lèi)： 穩(wěn)壓器
英文描述： 0.01 A SWITCHING REGULATOR, PQCC16
封裝： PLASTIC, QFN-16
文件頁(yè)數(shù)： 24/26頁(yè)
文件大?。?/td> 907K
代理商： TPS54429ERSAT
(
)
(
)
2
IN
OUT
OUT LL
IN
V
I
L fsw
V
-
×
=
×
1
Tss(ms)=
C6(nF) Vref
Iss( A)
=
C6(nF) 0.765
2
SLVSAS0 –FEBRUARY 2011
OVERVIEW
The TPS54429E is a 4.5-A synchronous step-down (buck) converter with two integrated N-channel MOSFETs
and auto-skip Eco-mode to improve light lode efficiency. It operates using D-CAP2 mode control. The fast
transient response of D-CAP2 control reduces the output capacitance required to meet a specific level of
performance. Proprietary internal circuitry allows the use of low ESR output capacitors including ceramic and
special polymer types.
DETAILED DESCRIPTION
PWM Operation
The main control loop of the TPS54429E is an adaptive on-time pulse width modulation (PWM) controller that
supports a proprietary D-CAP2 mode control. D-CAP2 mode control combines constant on-time control with
an internal compensation circuit for pseudo-fixed frequency and low external component count configuration with
both low ESR and ceramic output capacitors. It is stable with virtually no ripple at the output.
At the beginning of each cycle, the high-side MOSFET is turned on. The MOSFET is turned off after the internal
one-shot timer expires. The one-shot timer is set by the converter input voltage, VIN, and the output voltage, VO,
to maintain a pseudo-fixed frequency over the input voltage range, hence it is called adaptive on-time control.
The one-shot timer is reset and the high-side MOSFET is turned on again when the feedback voltage falls below
the reference voltage. An internal ramp is added to reference voltage to simulate output ripple, eliminating the
need for ESR induced output ripple from D-CAP2 mode control.
PWM Frequency and Adaptive On-Time Control
TPS54429E uses an adaptive on-time control scheme and does not have a dedicated on board oscillator. The
TPS54429E runs with a pseudo-constant frequency of 700 kHz by using the input voltage and output voltage to
set the on-time one-shot timer. The on-time is inversely proportional to the input voltage and proportional to the
output voltage. The actual frequency may vary from 700 kHz depending on the off time, which is ended when the
fed back portion of the output voltage falls to the VFB threshold voltage.
Auto-Skip Eco-Mode
Control
The TPS54429E is designed with Auto-Skip Eco-mode to increase light load efficiency. As the output current
decreases from heavy load condition, the inductor current is also reduced and eventually comes to point that its
rippled valley touches zero level, which is the boundary between continuous conduction and discontinuous
conduction modes. The rectifying MOSFET is turned off when its zero inductor current is detected. As the load
current further decreases the converter run into discontinuous conduction mode. The on-time is kept almost the
same as is was in the continuous conduction mode so that it takes longer time to discharge the output capacitor
with smaller load current to the level of the reference voltage. The transition point to the light load operation
IOUT(LL) current can be calculated in Equation 1.
(1)
Soft Start and Pre-Biased Soft Start
The soft start function is adjustable. When the EN pin becomes high, 2 μA current begins charging the capacitor
which is connected from the SS pin to GND. Smooth control of the output voltage is maintained during start up.
The equation for the slow start time is shown in Equation 2. VFB voltage is 0.765 V and SS pin source current is
2 μA.
(2)
2011, Texas Instruments Incorporated
7
Product Folder Link(s) :TPS54429E
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TPS54429PWP 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 7V-18Vin,4.5A Sync Step-Down DCAP2 Mode RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
TPS54429PWPR 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 7V-18Vin,4.5A Sync Step-Down DCAP2 Mode RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
TPS54478 制造商:TI 制造商全稱:Texas Instruments 功能描述:2.95-V to 6-V Input, 4-A Output, 2-MHz, Synchronous Step-Down
TPS54478EVM-037 功能描述:電源管理IC開(kāi)發(fā)工具 TPS54478 Eval Mod RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類(lèi)型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V
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