Motor de Búsqueda de Datasheet de Componentes Electrónicos
  Spanish  ▼
ALLDATASHEET.ES

X  

TC7662AIJA Datasheet(PDF) 3 Page - Microchip Technology

No. de pieza TC7662AIJA
Descripción Electrónicos  CHARGE PUMP DC-TO-DC CONVERTER
Download  7 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Fabricante Electrónico  MICROCHIP [Microchip Technology]
Página de inicio  http://www.microchip.com
Logo MICROCHIP - Microchip Technology

TC7662AIJA Datasheet(HTML) 3 Page - Microchip Technology

  TC7662AIJA Datasheet HTML 1Page - Microchip Technology TC7662AIJA Datasheet HTML 2Page - Microchip Technology TC7662AIJA Datasheet HTML 3Page - Microchip Technology TC7662AIJA Datasheet HTML 4Page - Microchip Technology TC7662AIJA Datasheet HTML 5Page - Microchip Technology TC7662AIJA Datasheet HTML 6Page - Microchip Technology TC7662AIJA Datasheet HTML 7Page - Microchip Technology  
Zoom Inzoom in Zoom Outzoom out
 3 / 7 page
background image
3
CHARGE PUMP DC-TO-DC CONVERTER
TC7662A
TC7662A-5 9/11/96
© 2001 Microchip Technology Inc.
DS21468
Note one of its characteristics is ESR (equivalent series
resistance). This parasitic resistance winds up in series with
the load. Thus, both voltage and power conversion effi-
ciency are compromised if a low ESR capacitor is not used.
For example, in the "Test Circuit", changing CP and CR
capacitors from typical ESR to low ESR types, the effective
converter output impedance changed from 45
Ω to 40Ω, an
improvement of 12%.
This applies to all types of capacitors, including film
types (polyester, polycarbonate etc.).
Some applications information suggests that the ca-
pacitor is not critical and attributes the limiting factor to the
capacitor's reactance value. Let's examine this:
where DS (duty cycle) = 50%.
Thus, ZC ≈ 1.33Ω at f = 12kHz, where C = 10µF.
For the TC7662A, f = 12,000Hz, and a typical value of
C would be 10
µF. This is a reactive impedance of ≈1.33Ω.
If the ESR is as great as 5
Ω, the reactive value is not as
critical as it would first appear, since the ESR would dominate.
The 5
Ω value is typical of a general-purpose electrolytic
capacitor.
Synchronizing
The TC7662A may be synchronized by connecting pin
7 of the TC7662A through a 100k resistor in series with a
diode to a negative-going pulse source. The negative pulse
voltage can be +5V with a 5 microsecond duration going
negative to 0V.
TEST CIRCUIT
Figure 2.
Synchronization
XC =
and ZC =
,
XC
DS
APPLICATIONS INFORMATION
Theory of Operation
The TC7662A is a capacitive charge pump (some-
times 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 C1 to the supply voltage, VDD. This
assumes that the ON resistance of the MOSFETs in series
with the capacitor produce a charging time (3 time con-
stants) less than the ON time provided by the oscillator
frequency, as shown:
3 (RDS(ON) C1) <C1/(0.5 fOSC).
In the next cycle, SW1 and SW2 are turned OFF and,
after a very short interval with all switches OFF (preventing
large currents from occurring due to cross conduction),
SW3 and SW4 are turned ON. The charge in C1 is then
transferred to COUT, BUT WITH THE POLARITY IN-
VERTED. In this way, a negative voltage is derived.
An oscillator supplies pulses to a flip-flop that is 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 a pin that controls the frequency of
oscillation. Pin 7 can have a capacitor added that is con-
nected to ground. This will lower the frequency of the
oscillator by adding capacitance to the internal timing ca-
pacitor of the TC7662A. (See Oscillator Frequency vs. CEXT,
page 5.)
Capacitors
In early charge pump converters, capacitors were not
considered critical due to the high RDS(ON) of the MOSFET
switches. In order to understand this, let’s look at a model of
a typical electrolytic capacitor (Figure 1).
1
2
πf C
TC7662A
1
2
3
4
8
7
5
CP
+
10
µF
COSC
R L
V
(–5V)
OUT
10
µF
C R
I L
IS
V
(+5V)
+
NC
NC
6
+
TTL
Q
Q
100 k
TO PIN 7
TC7662A
Figure 1.
Capacitor Equivalent Circuit
EPR
ESL
ESR
C


Número de pieza similar - TC7662AIJA

Fabricante ElectrónicoNo. de piezaDatasheetDescripción Electrónicos
logo
TelCom Semiconductor, I...
TC7662AIJA TELCOM-TC7662AIJA Datasheet
62Kb / 5P
   CHARGE PUMP DC-TO-DC CONVERTER
logo
Microchip Technology
TC7662AIJA MICROCHIP-TC7662AIJA Datasheet
457Kb / 14P
   Charge Pump DC-to-DC Converter
2002
TC7662AIJA MICROCHIP-TC7662AIJA Datasheet
231Kb / 16P
   Charge Pump DC-to-DC Converter
11/29/12
More results

Descripción similar - TC7662AIJA

Fabricante ElectrónicoNo. de piezaDatasheetDescripción Electrónicos
logo
Microchip Technology
TC7662A MICROCHIP-TC7662A_13 Datasheet
231Kb / 16P
   Charge Pump DC-to-DC Converter
11/29/12
logo
TelCom Semiconductor, I...
TC7662A TELCOM-TC7662A Datasheet
62Kb / 5P
   CHARGE PUMP DC-TO-DC CONVERTER
logo
Microchip Technology
TC7662A MICROCHIP-TC7662A_02 Datasheet
457Kb / 14P
   Charge Pump DC-to-DC Converter
2002
TC7660 MICROCHIP-TC7660 Datasheet
91Kb / 12P
   CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER
2001
logo
ON Semiconductor
MC7660 ONSEMI-MC7660 Datasheet
191Kb / 12P
   Charge Pump DC-to-DC Voltage Converter
February, 2000 ??Rev. 2
logo
Microchip Technology
TC1044S MICROCHIP-TC1044S Datasheet
92Kb / 11P
   Charge Pump DC-TO-DC Voltage Converter
2001
logo
TelCom Semiconductor, I...
TC1044S TELCOM-TC1044S Datasheet
141Kb / 8P
   CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER
TC7662B TELCOM-TC7662B Datasheet
133Kb / 9P
   CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER
logo
Microchip Technology
TC7660 MICROCHIP-TC7660_16 Datasheet
1Mb / 20P
   Charge Pump DC-to-DC Voltage Converter
11/29/11
TC7660 MICROCHIP-TC7660_02 Datasheet
386Kb / 18P
   Charge Pump DC-to-DC Voltage Converter
2002
More results


Html Pages

1 2 3 4 5 6 7


Datasheet Descarga

Go To PDF Page


Enlace URL




Política de Privacidad
ALLDATASHEET.ES
¿ALLDATASHEET es útil para Ud.?  [ DONATE ] 

Todo acerca de Alldatasheet   |   Publicidad   |   Contáctenos   |   Política de Privacidad   |   Intercambio de Enlaces   |   Lista de Fabricantes
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com