- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄361413 > TC962CPA (Microchip Technology Inc.) High Current Charge Pump DC-to-DC Converter PDF資料下載
參數(shù)資料
| 型號： | TC962CPA |
| 廠商： | Microchip Technology Inc. |
| 英文描述： | High Current Charge Pump DC-to-DC Converter |
| 中文描述： | 高電流電荷泵DC - DC轉(zhuǎn)換器 |
| 文件頁數(shù)： | 3/5頁 |
| 文件大?。?/td> | 74K |
| 代理商： | TC962CPA |
4-39
TELCOM SEMICONDUCTOR, INC.
7
6
5
4
3
1
2
8
HIGH CURRENT CHARGE PUMP
DC-TO-DC CONVERTER
TC962
This applies to all types of capacitors, including film
types (polyester, polycarbonate, etc.).
Some applications information suggest that the capaci-
tor is not critical and attribute the limiting factor of the
capacitor to its reactive value. Let's examine this:
1
2
π
f C
where DS (duty cycle) = 50%.
Thus, Z
C
≈
2.6
at f = 12kHz, where C = 10
μ
F.
For the TC962, f = 12,000 Hz, and a typical value of C
would be 10
μ
F. This is a reactive impedance of
'
2.6
. If
the ESR is as great as 5
, the reactive value is not as critical
as it would first appear, as the ESR would predominate.
The 5
value is typical of a general-purpose electrolytic
capacitor.
TEST CIRCUIT
Latch Up
All CMOS structures contain a parasitic SCR. Care must
be taken to prevent any input from going above or below the
supply rail, or latch up will occur. The result of latch up is an
effective short between V
DD
and V
SS
. Unless the power
supply input has a current limit, this latch-up phenomena will
result in damage to the device. (See Application Note 31 for
additional information.)
APPLICATIONS INFORMATION
Theory of Operation
The TC962 is a capacitive pump (sometimes called a
switched capacitor circuit), where four MOSFET switches
control the charge and discharge of a capacitor.
The functional diagram (page 1) shows how the switch-
ing action works. SW1 and SW2 are turned on simulta-
neously, charging C
P
to the supply voltage, V
IN
. This as-
sumes that the on resistance of the MOSFETs in series
with the capacitor results in a charging time (3 time con-
stants) that is less than the on time provided by the oscilla-
tor frequency as shown:
3 (R
DS(ON)
C
P
) <C
P
/(0.5 f
OSC
)
In the next cycle, SW1 and SW2 are turned off and
after a very short interval of all switches being off (this
prevents large currents from occurring due to cross con-
duction), SW3 and SW4 are turned on. The charge in C
P
is
then transferred to C
R
, BUT WITH THE POLARITY IN-
VERTED. In this way, a negative voltage is now derived.
Page 1 shows a functional diagram of the TC962. An
oscillator supplies pulses to a flip-flop that is then fed to a
set of level shifters. These level shifters then drive each set
of switches at one-half the oscillator frequency.
The oscillator has two pins that control the frequency of
oscillation. Pin 7 can have a capacitor added that is re-
turned to ground. This will lower the frequency of the
oscillator by adding capacitance to the timing capacitor
internal to the TC962. Grounding pin 6 will turn on a
current source and double the frequency. This will double
the charge current going into the internal capacitor, as well
as any capacitor added to pin 7.
A zener diode has been added to the TC962 for use as
a reference in building external regulators. This zener runs
from pin 1 to ground.
Capacitors
In early charge pump converters, the capacitors were
not considered critical due to the high R
DS(ON)
of the MOS-
FET switches. In order to understand this, let’s look at a
model of a typical electrolytic capacitor (Figure 1).
Note that one of its characteristics is ESR (equivalent
series resistance). This parasitic resistance winds up in
series with the load. Thus, both voltage conversion effi-
ciency and power conversion efficiency are compromised if
a low ESR capacitor is not used.
In the test circuit, for example, just changing two capaci-
tors, C
P
and C
R
, from capacitors with unspecified ESR to low
ESR-type output, impedance changes from 36
to 28
, an
improvement of 23%!
X
C
=
and Z
C
= X
C
DS
ESL
ESR
C
Figure 1. Typical Electrolytic Capacitor
TC962
1
2
3
4
8
690
7
5
CP
+
10
μ
F
COSC
RL
V
(–5V)
OUT
10
μ
F
CR
IL
IS
V
(+5V)
+
NC
+
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| TC962EPA | High Current Charge Pump DC-to-DC Converter |
| TC962MJA | High Current Charge Pump DC-to-DC Converter |
| TC962COE | High Current Charge Pump DC-to-DC Converter |
| TC962 | HIGH CURRENT CHARGE PUMP DC-TO-DC CONVERTER |
| TC962CPA | HIGH CURRENT CHARGE PUMP DC-TO-DC CONVERTER |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TC962EOE | 功能描述:IC REG SWITCHED CAP INV 16SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 產(chǎn)品培訓(xùn)模塊:MIC23xxx HyperLight Load™ Regulators 標(biāo)準(zhǔn)包裝:5,000 系列:HyperLight Load® 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.8V 輸入電壓:2.7 V ~ 5.5 V PWM 型:混合物 頻率 - 開關(guān):4MHz 電流 - 輸出:2A 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:8-VFDFN 裸露焊盤，8-MLF? 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-MLF?（2x2） 產(chǎn)品目錄頁面:1094 (CN2011-ZH PDF) 其它名稱:576-3303-2 |
| TC962EPA | 功能描述:電荷泵 High Output RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 輸出電壓:- 1.5 V to - 5.5 V, 3 V to 11 V 輸出電流:100 mA 電源電流:1 mA 最大工作溫度:+ 70 C 封裝 / 箱體:SOIC-8 Narrow 封裝:Tube |
| TC962IJA | 功能描述:電荷泵 High Output RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 輸出電壓:- 1.5 V to - 5.5 V, 3 V to 11 V 輸出電流:100 mA 電源電流:1 mA 最大工作溫度:+ 70 C 封裝 / 箱體:SOIC-8 Narrow 封裝:Tube |
| TC962MJA | 功能描述:電荷泵 High Output RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 輸出電壓:- 1.5 V to - 5.5 V, 3 V to 11 V 輸出電流:100 mA 電源電流:1 mA 最大工作溫度:+ 70 C 封裝 / 箱體:SOIC-8 Narrow 封裝:Tube |
| TC96C55 | 制造商:TELCOM 制造商全稱:TelCom Semiconductor, Inc 功能描述:3A OUTPUT PROGRAMMABLE POWER OSCILLATOR |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。