參數(shù)資料
型號(hào)： MAX1714BEEE
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： 穩(wěn)壓器
英文描述： High-Speed Step-Down Controller for Notebook Computers
中文描述： SWITCHING CONTROLLER, 600 kHz SWITCHING FREQ-MAX, PDSO16
封裝： 0.150 INCH, 0.025 INCH PITCH, MO-137AA, QSOP-16
文件頁(yè)數(shù)： 14/24頁(yè)
文件大?。?/td> 443K
代理商： MAX1714BEEE
M
High-Speed Step-Down Controller
for Notebook Computers
14
______________________________________________________________________________________
POR, UVLO, and Soft-Start
Power-on reset (POR) occurs when V
CC
rises above
approximately 2V, resetting the fault latch and soft-start
counter, and preparing the PWM for operation. V
CC
undervoltage lockout (UVLO) circuitry inhibits switching
and forces the DL gate driver high (to enforce output
overvoltage protection) until V
CC
rises above 4.2V,
whereupon an internal digital soft-start timer begins to
ramp up the maximum allowed current limit. The ramp
occurs in five steps: 20%, 40%, 60%, 80%, and 100%;
100% current is available after 1.7ms ±50%.
A continuously adjustable analog soft-start function can
be realized by adding a capacitor in parallel with the
ILIM resistor. This soft-start method requires a minimum
interval between power-down and power-up to dis-
charge the capacitor.
Power-Good Output (PGOOD)
The output voltage is continuously monitored for under-
voltage by the PGOOD comparator. In shutdown,
standby, and soft-start, PGOOD is actively held low.
After digital soft-start has terminated, PGOOD is
released if the digital output is within 6% of the error-
comparator threshold. The PGOOD output is a true
open-drain type with no parasitic ESD diodes. Note that
the PGOOD undervoltage detector is completely inde-
pendent of the output UVP fault detector.
Output Overvoltage Protection
The overvoltage protection (OVP) circuit is available in
the MAX1714A only, and is designed to protect against
a shorted high-side MOSFET by drawing high current
and blowing the battery fuse. The output voltage is con-
tinuously monitored for overvoltage. If the output is more
than 12.5% above the trip level of the error amplifier,
overvoltage protection (OVP) is triggered and the circuit
shuts down. The DL low-side gate-driver output is
then latched high until
SHDN
is toggled or V
CC
power is
cycled below 1V. This action turns on the synchronous-
rectifier MOSFET with 100% duty and, in turn, rapidly
discharges the output filter capacitor and forces the out-
put to ground. If the condition that caused the overvolt-
age (such as a shorted high-side MOSFET) persists, the
battery fuse will blow. DL is also kept high continuously
when V
CC
UVLO is active, as well as in shutdown mode
(Table 3).
Note that DL latching high causes the output voltage to
go slightly negative, due to energy stored in the output
LC tank circuit when OVP activates. If the load can’t tol-
erate being forced to a negative voltage, it may be desir-
able to place a power Schottky diode across the output
to act as a reverse-polarity clamp.
Overvoltage protection can be defeated using the no-
fault test mode (see
No-Fault Test Mode
section).
Output Undervoltage Protection
The output undervoltage protection (OVP) function is
similar to foldback current limiting, but employs a timer
rather than a variable current limit. If the MAX1714 out-
put voltage is under 70% of the nominal value 20ms after
coming out of shutdown, the PWM is latched off and
won’t restart until V
CC
power is cycled or
SHDN
is tog-
gled. Under- voltage protection can be defeated using
the no-fault test mode.
No-Fault Test Mode
The over/undervoltage protection features can compli-
cate the process of debugging prototype breadboards,
since there are (at most) a few milliseconds in which to
determine what went wrong. Therefore, a test mode is
provided to totally disable the OVP, UVP, and thermal
shutdown features, and clear the fault latch if it has been
set. The PWM operates as if
SKIP
were grounded
(PFM/PWM mode).
The no-fault test mode is entered by sinking 1.5mA from
SKIP
through an external negative voltage source in
series with a resistor (Figure 6).
SKIP
is clamped to
AGND with a silicon diode, so choose a resistor value of
approximately (V
FORCE
- 0.65V) / 1.5mA.
Design Procedure
Component selection for the MAX1714 is primarily dic-
tated by the following four criteria:
1)
Input voltage range
. The maximum value (V
IN(MAX)
)
must accommodate the worst-case high AC adapter
voltage. The minimum value (V
IN(MIN)
) must account
for the lowest battery voltage after drops due to con-
nectors, fuses, and battery selector switches. If
there is a choice at all, lower input voltages result in
better efficiency.
BST
+5V
V
IN
5
DH
LX
MAX1714
Figure 5. Reducing the Switching-Node Rise Time
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參數(shù)描述
MAX1714BEEE+ 功能描述:電流型 PWM 控制器 Step-Down Controller for Notebook RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX1714BEEE+T 功能描述:電流型 PWM 控制器 Step-Down Controller for Notebook RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX1714BEEE-T 功能描述:電流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX1714BEEE-TG074 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
MAX1714BEVKIT 功能描述:電流型 PWM 控制器 Evaluation Kit for the MAX1714B RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
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