- 您現(xiàn)在的位置：買賣IC網 > PDF目錄377766 > LTYB (Linear Technology Corporation) 100mA REGULATED CHARGE-PUMP INVERTERS IN THINSOT PDF資料下載
參數(shù)資料
| 型號： | LTYB |
| 廠商： | Linear Technology Corporation |
| 英文描述： | 100mA REGULATED CHARGE-PUMP INVERTERS IN THINSOT |
| 中文描述： | 100mA的穩(wěn)壓電荷泵采用ThinSOT逆變器中 |
| 文件頁數(shù)： | 7/12頁 |
| 文件大小： | 188K |
| 代理商： | LTYB |
LTC1983-3/LTC1983-5
7
sn1983 1983fs
There are many aspects of the capacitors that must be
taken into account. First, the temperature stability of the
dielectric is a main concern. For ceramic capacitors, a
three character code specifies the temperature stability
(e.g. X7R, Y5V, etc.). The first two characters represent
the temperature range that the capacitor is specified and
the third represents the absolute tolerance that the ca-
pacitor is specified to over that temperature range.
The
ceramic capacitor used for the flying and output capaci-
tors should be X5R or better
. Second, the voltage coef-
ficient of capacitance for the capacitor must be checked
and the actual value usually needs to be derated for the
operating voltage (the actual value has to be larger than
the value needed to take into account the loss of capaci-
tance due to voltage bias across the capacitor). Third, the
frequency characteristics need to be taken into account
because capacitance goes down as the frequency of
oscillation goes up. Typically, the manufacturers have
capacitance vs frequency curves for their products. This
curve must be referenced to be sure the capacitance will
not be too small for the application. Finally, the capacitor
ESR and ESL must be low for reasons mentioned in the
following section.
Output Ripple
Normal LTC1983 operation produces voltage ripple on the
V
OUT
pin. Output voltage ripple is required for the LTC1983
to regulate. Low frequency ripple exists due to the hyster-
esis in the sense comparator and propagation delays in the
charge pump enable/disable circuits. High frequency ripple
is also present mainly due to ESR of the output capacitor.
Typical output ripple under maximum load is 60mV
P-P
with a low ESR 10
μ
F output capacitor. The magnitude of
the ripple voltage depends on several factors. High input
voltage to negative output voltage differentials [(V
IN
+
V
OUT
) >1V] increase the output ripple since more charge
is delivered to C
OUT
per clock cycle. A large flying capacitor
(>1
μ
F) also increases ripple for the same reason. Large
output current load and/or a small output capacitor (<10
μ
F)
results in higher ripple due to higher output voltage dV/dt.
High ESR capacitors (ESR > 0.1
) on the output pin cause
high frequency voltage spikes on V
OUT
with every clock
cycle.
There are several ways to reduce the output voltage ripple.
A larger C
OUT
capacitor (22
μ
F or greater) will reduce both
the low and high frequency ripple due to the lower C
OUT
charging and discharging dV/dt and the lower ESR typi-
cally found with higher value (larger case size) capacitors.
A low ESR ceramic output capacitor will minimize the high
frequency ripple, but will not reduce the low frequency
ripple unless a high capacitance value is chosen. A reason-
able compromise is to use a 10
μ
F to 22
μ
F tantalum
capacitor in parallel with a 1
μ
F to 4.7
μ
F ceramic capacitor
on V
OUT
to reduce both the low and high frequency ripple.
However, the best solution is to use 10
μ
F to 22
μ
F, X5R
ceramic capacitors which are available in 1206 package
sizes. An RC filter may also be used to reduce high
frequency voltage spikes (see Figure 1).
In low load or high V
IN
applications, smaller values for
C
FLY
may be used to reduce output ripple. A smaller flying
capacitor (0.01
μ
F to 0.047
μ
F) delivers less charge per
clock cycle to the output capacitor resulting in lower
output ripple. However, the smaller value flying caps also
reduce the maximum I
OUT
capability as well as efficiency.
Figure 1. Output Ripple Reduction Techniques
V
OUT
V
OUT
LTC1983-X
10
μ
F
TANTALUM
10
μ
F
TANTALUM
V
OUT
V
OUT
LTC1983-X
15
μ
F
TANTALUM
1
μ
F
CERAMIC
3.9
1983 F01
OPERATIOU
(Refer to Block Diagram)
相關PDF資料 |
PDF描述 |
|---|---|
| LTC1985-1.8 | 5V High-Speed RS-232 Transceivers with 0.1uF Capacitors |
| LTC1985ES5-1.8 | Micropower Precision Triple Supply Monitor with Push-Pull Reset Output in a 5-Lead SOT-23 Package |
| LTC1986ES6 | Quadruple Bus Buffer Gates With 3-State Outputs 14-TVSOP -40 to 85 |
| LTC1986 | 3V/5V SIM Power Supply,Micropower Charge Pump DC/DC Converter(用于3V/5V SMI電源,微功耗電荷泵DC/DC變換器) |
| LTC1992 | 2.5uA, 1% Accurate SOT-23 Comparator and Voltage Reference for Battery Monitoring |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LTYK | 功能描述:電纜束帶 Rack Grounding Yellow Tag Kit, 10 tags & RoHS:否 制造商:Phoenix Contact 產品:Cable Tie Mounts 類型:Adhesive 顏色:Black 材料:Acrylonitrile Butadiene Styrene (ABS) 長度:19 mm 寬度:19 mm 抗拉強度: |
| LTZ | 制造商:AURIS 制造商全稱:AURIS 功能描述:Filter THT |
| LTZ1000 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Ultra Precision Reference |
| LTZ1000_06 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Ultra Precision Reference |
| LTZ1000_12 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Ultra Precision Reference |
發(fā)布緊急采購，3分鐘左右您將得到回復。