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參數(shù)資料
| 型號： | LTC1998CS6 |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 電源管理 |
| 英文描述： | Quadruple Bus Buffer Gates With 3-State Outputs 14-SO -40 to 85 |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO6 |
| 封裝： | 1 MM HEIGHT, PLASTIC, MO-193, TSOT-23, 6 PIN |
| 文件頁數(shù)： | 6/8頁 |
| 文件大小： | 143K |
| 代理商： | LTC1998CS6 |
LTC1998
6
1998f
Figure 3. Combined Resistor Divider
1998 F03
LTC1998
R1
R2
R3
V
H.A
V
TH.A
BATT
+
L
1
4
3
The simple calculations of resistor values R1 and R2 are
illustrated below. Set a value for R1 + R2. This value will
affect the max amount of current drawn from the battery
when fully charged. For instance if R1 + R2 = 1M the
resistive divider will draw 4.1
μ
A when the battery voltage
is 4.1V. Set the desired value of V
BATT.Th
(this value should
be between 2.5V and 3.25V) that is the value of the battery
voltage that will trip the internal circuitry of the LTC1998
and change the state of the battery low pin (BATTLO).
Solve for R
R
(
R
V
V
BATT Th
1
1
2
5
1
=
+
)
–
.
Example: A Lithium-Ion battery is monitored and a battery
low signal should be issued when it discharges to 2.85V,
that is, V
BATT.Th
= 2.85V; if (R1 + R2) = 1M, then
R1 = 754.38k and R2 = 245.62k. Choose the closest 1%
value of R1 = 750k and R2 = 243k. Calculate the practical
value for V
BATT.Th
as it will be slightly different from 2.85V,
due to the use of standard 1% resistor values.
V
V
R
+
R
+
1
R
R
(
R
V
BATT Th
.
)
.
=
+
=
5
1
2
1
2
2 849
The above low battery threshold of 2.849V is guaranteed
to within 1% even though 1% resistors are used to
program the V
TH.A
voltage applied to Pin 3.
For sake of completeness, the voltage at Pin 3 (V
TH.A
) can
be easily calculated by V
TH.A
= V
BATT.Th
(R2/(R1 + R2) =
0.6972V (when V
BATTERY
= V
BATT.Th
).
Hysteresis Adjustment, Pin 4.
The LTC1998 has an adjustable hysteresis ranging from
10mV to 0.75V. A large hysteresis is useful in the event
that a low battery signal at the LTC1998’s BATTLO pin
causes the system to shed some battery load, thus induc-
ing system confusion as the partially loaded battery recov-
ers and changes the status of Pin 6 (BATTLO). The 2.5V to
3.25V programming window of low battery threshold
voltage includes the hysteresis. If, for instance, the low
battery threshold voltage is set to 2.5V, 750mV hysteresis
can be added on top of the 2.5V. If the low battery
threshold voltage is set to 3.15V, only 100mV hysteresis
can be applied.
The programming of the hysteresis threshold adjust pin
(V
H.A
) is similar to the programming of the voltage thresh-
old adjust pin (V
TH.A
) already described in the previous
paragraph. Pin 4 effectively adjusts the threshold voltage
at which the low battery pin (BATTLO) changes state from
low to high. This threshold (V
TH2
) is defined as:
V
V
V
(
TH
H A
2
2
2 5
.
=
+
)
.
The actual hysteresis voltage is:
V
HYST
= V
TH2
– V
BATT.Th
It is imperative that the hysteresis threshold adjust voltage
at Pin 4 be set to a higher voltage than the low battery
threshold adjust voltage at Pin 3, at all times, to avoid
oscillation at the BATTLO output pin. The hysteresis
threshold adjust pin may be set with a voltage source or
with a resistor divider, just as with the low battery thresh-
old adjust pin.
Combined Control of Threshold and Hysteresis
If a resistor divider is desired, then both threshold adjust
dividers can be combined in order to save current. This
simple technique also guarantees that the hysteresis thresh-
old adjust voltage at Pin 4 is higher than the voltage at the
V
TH.A
pin, Figure 3.
The calculation of the resistor values R1, R2 and R3 is
quite straightforward and similar to the procedure out-
lined in the previous paragraph.
Choose a value for the sum of R1 + R2 + R3 as well as the
values for low battery threshold and hysteresis.
Solve for resistor R1:
APPLICATIOU
W
U
U
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1998CS6#PBF | 制造商:Linear Technology 功能描述:Comparator and Voltage Reference 6-Pin TSOT-23 |
| LTC1998CS6#TR | 功能描述:IC COMP/PREC ADJ REF TSOT23-6 RoHS:否 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 標準包裝:61 系列:- 功能:電源管理 電池化學:鋰離子（Li-Ion）、鋰聚合物（Li-Pol） 電源電壓:4.35 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:22-WFDFN 裸露焊盤 供應商設備封裝:22-DFN（6x3）裸露焊盤 包裝:管件 |
| LTC1998CS6#TRM | 功能描述:IC DETECT VOLT PR LOBATT SOT23-6 RoHS:否 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 標準包裝:61 系列:- 功能:電源管理 電池化學:鋰離子（Li-Ion）、鋰聚合物（Li-Pol） 電源電壓:4.35 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:22-WFDFN 裸露焊盤 供應商設備封裝:22-DFN（6x3）裸露焊盤 包裝:管件 |
| LTC1998CS6#TRMPBF | 功能描述:IC DETECT VOLT PR LOBATT SOT23-6 RoHS:是 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 標準包裝:2,000 系列:Impedance Track™ 功能:燃料，電量檢測計/監(jiān)控器 電池化學:鋰離子（Li-Ion） 電源電壓:2.4 V ~ 2.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:20-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:20-TSSOP 包裝:帶卷 (TR) 產(chǎn)品目錄頁面:1020 (CN2011-ZH PDF) 配用:BQ27350EVM-ND - BQ27350EVM 其它名稱:296-21665-2 |
| LTC1998CS6#TRPBF | 功能描述:IC DETECT VOLT PR LOBATT SOT23-6 RoHS:是 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 標準包裝:61 系列:- 功能:電源管理 電池化學:鋰離子（Li-Ion）、鋰聚合物（Li-Pol） 電源電壓:4.35 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:22-WFDFN 裸露焊盤 供應商設備封裝:22-DFN（6x3）裸露焊盤 包裝:管件 |
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