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參數(shù)資料
| 型號： | LT1505CG |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 電源管理 |
| 英文描述： | Constant-Current/Voltage High Efficiency Battery Charger |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO28 |
| 封裝： | 5.30 MM, PLASTIC, SSOP-28 |
| 文件頁數(shù)： | 11/16頁 |
| 文件大?。?/td> | 214K |
| 代理商： | LT1505CG |
11
LT1505
APPLICATIO
S I
FOR
ATIO
U
EMI considerations usually make it desirable to minimize
ripple current in the battery leads. Beads or inductors may
be added to increase battery impedance at the 200kHz
switching frequency. Switching ripple current splits be-
tween the battery and the output capacitor depending on
the ESR of the output capacitor and the battery imped-
ance. If the ESR of C
OUT
is 0.2
and the battery impedance
is raised to 4
with a bead or inductor, only 5% of the
ripple current will flow in the battery.
Soft Start and Undervoltage Lockout
The LT1505 is soft started by the 0.33
μ
F capacitor on the
V
C
pin. On start-up, the V
C
pin voltage will rise quickly to
0.5V, then ramp up at a rate set by the internal 45
μ
A pull-
up current and the external capacitor. Battery charge
current starts ramping up when V
C
voltage reaches 0.7V
and full current is achieved with V
C
at 1.1V. With a 0.33
μ
F
capacitor, time to reach full charge current is about 10ms
and it is assumed that input voltage to the charger will
reach full value in less than 10ms. The capacitor can be
increased up to 1
μ
F if longer input start-up times are
needed.
In any switching regulator, conventional timer-based soft
starting can be defeated if the input voltage rises much
slower than the time out period. This happens because the
switching regulators in the battery charger and the com-
puter power supply are typically supplying a fixed amount
of power to the load. If input voltage comes up slowly
compared to the soft start time, the regulators will try to
deliver full power to the load when the input voltage is still
well below its final value. If the adapter is current limited,
it cannot deliver full power at reduced output voltages and
the possibility exists for a quasi “l(fā)atch” state where the
adapter output stays in a current limited state at reduced
output voltage. For instance, if maximum charger plus
computer load power is 30W, a 15V adapter might be
current limited at 2.5A. If adapter voltage is less than
(30W/2.5A = 12V) when full power is drawn, the adapter
voltage will be pulled down by the constant 30W load until
it reaches a lower stable state where the switching regu-
lators can no longer supply full load. This situation can be
prevented by setting undervoltage ockout higher than the
minimum adapter voltage where full power can be achieved.
W
U
U
Figure 2. Adapter Current Limiting
92mV
–
+
500
CLP
CLN
V
CC
UV
1505 F02
R5
LT1505
R6
1
μ
F
+
R
S4
*
C
IN
V
IN
CL1
AC ADAPTER
OUTPUT
*R
S4
=
92mV
ADAPTER CURRENT LIMIT
+
A resistor divider is used to set the desired V
CC
lockout
voltage as shown in Figure 2. A typical value for R6 is 5k
and R5 is found from:
R5=R6(V
– V
)
V
UV
UV
IN
V
UV
= Rising lockout threshold on the UV pin
V
IN
= Charger input voltage that will sustain full load power
Example: With R6 = 5k, V
UV
= 6.7V and setting V
IN
at 16V;
R5 = 5k (16V – 6.7V)/6.7V = 6.9k
The resistor divider should be connected directly to the
adapter output as shown, not to the V
CC
pin to prevent
battery drain with no adapter voltage. If the UV pin is not
used, connect it to the adapter output (not V
CC
) and
connect a resistor no greater than 5k to ground. Floating
the pin will cause reverse battery current to increase from
10
μ
A to 200
μ
A.
Adapter Current Limiting
(Not Applicable for the LT1505-1)
An important feature of the LT1505 is the ability to
automatically adjust charge current to a level which avoids
overloading the wall adapter. This allows the product to
operate at the same time batteries are being charged
without complex load management algorithms. Addition-
ally, batteries will automatically be charged at the maximum
possible rate of which the adapter is capable.
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相關代理商/技術參數(shù) |
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| LT1505CG#PBF | 功能描述:IC BATT CHARGER CONST I/V 28SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:- 功能:電池監(jiān)控器 電池化學:堿性，鋰離子，鎳鎘，鎳金屬氫化物 電源電壓:1 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 供應商設備封裝:SOT-6 包裝:帶卷 (TR) |
| LT1505CG#TR | 功能描述:IC CHARGER BATT CONST V/I 28SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:- 功能:電池監(jiān)控器 電池化學:堿性，鋰離子，鎳鎘，鎳金屬氫化物 電源電壓:1 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 供應商設備封裝:SOT-6 包裝:帶卷 (TR) |
| LT1505CG#TRPBF | 功能描述:IC BATT CHARGER CONST I/V 28SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:- 功能:電池監(jiān)控器 電池化學:堿性，鋰離子，鎳鎘，鎳金屬氫化物 電源電壓:1 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 供應商設備封裝:SOT-6 包裝:帶卷 (TR) |
| LT1505CG-1 | 功能描述:IC BATT CHARGER CONST I/V 28SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:- 功能:電池監(jiān)控器 電池化學:堿性，鋰離子，鎳鎘，鎳金屬氫化物 電源電壓:1 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 供應商設備封裝:SOT-6 包裝:帶卷 (TR) |
| LT1505CG-1#PBF | 功能描述:IC BATT CHARGER CONST I/V 28SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:- 功能:電池監(jiān)控器 電池化學:堿性，鋰離子，鎳鎘，鎳金屬氫化物 電源電壓:1 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 供應商設備封裝:SOT-6 包裝:帶卷 (TR) |
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