- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄361487 > TK65431M (TOKO Inc.) STEP-DOWN CONVERTER WITH BATTERY MONITOR PDF資料下載
參數(shù)資料
| 型號： | TK65431M |
| 廠商： | TOKO Inc. |
| 英文描述： | STEP-DOWN CONVERTER WITH BATTERY MONITOR |
| 中文描述： | 降壓轉(zhuǎn)換器與電池監(jiān)視器 |
| 文件頁數(shù)： | 13/28頁 |
| 文件大?。?/td> | 762K |
| 代理商： | TK65431M |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁當(dāng)前第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁
September 1999 TOKO, Inc.
Page 13
TK654xx
ADVANCED INFORMATION
DESIGN CONSIDERATIONS
INDUCTOR SELECTION
One of the positive features of the TK654xx is the ability to
limit the magnitude of the short circuit current without the
need for external current sensing resistors. Since the
maximum on-time duration is limited, and the converter
always operates in discontinuous conduction mode (DCM),
the maximum load current is essentially dependent upon
the selection of the inductor value. The following table
defines the maximum load current as a function of the
inductor value.
OUTPUT FILTER CAPACITOR SELECTION
The purpose of the filter capacitor on the output is to
temporarily provide current to the load as inductor current
is ramping upward or downward. In general, larger
capacitors will reduce the magnitude of the ripple.
INPUT FILTER CAPACITOR SELECTION
Typically, the power supply or battery source connected to
the V
IN
pin contains an inductive and resistive component.
Since the current draw from the input supply varies with
time, such a scenario would exhibit ripple on the input
supply. Adding a bypass capacitor between the V
IN
pin
and ground, in some cases, will dramatically decrease
ripple on the input supply. An input supply bypass capacitor
in the range of 1 to 10
μ
F will work well for most converter
applications up to 100 mA. Bypass capacitors on the input
pin should exhibit relatively good ESR characteristics.
LOW BATTERY MONITOR
The TK654xx utilizes a proprietary method for sensing and
handling low battery voltages. Using a single input pin and
resistive divider, the TK654xx not only provides an early
warning system of a low battery, it also provides a later
L
MAX LOAD
47 μH
305 mA
100 μH
140 mA
220 μH
65 mA
470 μH
20 mA
R1
R2
300 k
VIN
OLBO
VOUT
LBO
VIN
SW
GND
LBI/SB
FIGURE 3: LOW BATTERY MONITOR
shutdown threshold which occurs at a voltage lower than
the LBI threshold. Both the LBI threshold and the shutdown
threshold can be set utilizing a single resistive divider.
For the following explanation, please refer to Figure 3.
When the battery voltage (V
IN
) is very high, the current
from the LBI input pin is essentially zero. The voltage on
the LBI input pin is simply a resistively-divided version of
the V
IN
pin.
As the voltage on the LBI input pin drops and passes
through the bandgap voltage (1.22 V), the LBI input pin will
begin to source current. At this same point, the LBO output
will be asserted. The assertion of the LBO output is
typically used as an early warning, indicating that battery
failure is approaching.
As the voltage on the V
IN
pin continues to drop, the current
sourced by the LBI input pin will continue to linearly
increase with the drop-in supply voltage. The current from
the LBI input pin will attempt to keep the voltage pin at the
same potential as the bandgap reference (1.22 V).
Throughout this region, the LBO output is continuously
asserted.
The current sourced from the LBI input pin is internally
limited to a maximum of approximately 720 nA. As
mentioned above, the current from the LBI input pin
continues to increase as the supply voltage drops. When
the current from the LBI input pin reaches the 720 nA
threshold, the TK654xx will turn off. This essentially provides
a second threshold, less than the LBI/SB threshold, where
the system will turn off.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| TK65431MTL | STEP-DOWN CONVERTER WITH BATTERY MONITOR |
| TK65432M | STEP-DOWN CONVERTER WITH BATTERY MONITOR |
| TK65432MTL | STEP-DOWN CONVERTER WITH BATTERY MONITOR |
| TK65433 | STEP-DOWN CONVERTER WITH BATTERY MONITOR |
| TK65433M | STEP-DOWN CONVERTER WITH BATTERY MONITOR |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TK65431MTL | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:STEP-DOWN CONVERTER WITH BATTERY MONITOR |
| TK65431MTL/431 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:STEP-DOWN CONVERTER WITH BATTERY MONITOR |
| TK65432 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:STEP-DOWN CONVERTER WITH BATTERY MONITOR |
| TK65432M | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:STEP-DOWN CONVERTER WITH BATTERY MONITOR |
| TK65432MTL | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:STEP-DOWN CONVERTER WITH BATTERY MONITOR |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。