|
|
PDF TC115 Data sheet ( Hoja de datos )
| Número de pieza | TC115 | |
| Descripción | PFM/PWM Step-Up DC/DC Converter | |
| Fabricantes | Microchip | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de TC115 (archivo pdf) en la parte inferior de esta página. Total 14 Páginas | ||
|
No Preview Available !
TC115
PFM/PWM Step-Up DC/DC Converter
Features
• High Efficiency at Low Output Load Currents via
PFM Mode
• Assured Start-up at 0.9V
• 80µA (Typ) Supply Current
• 85% Typical Efficiency at 100mA
• 140mA Typical Output Current @ VIN = 2.0V
• Low Power Shutdown Mode
• No External Switching Transistor Needed
• Space Saving SOT-89 Package
Applications
• Pagers
• Cellular Phones
• Palmtops
• 1-Cell to 3-Cell Battery Powered Systems
• Cameras, Video Recorders
• Local +3V to +5V Supplies
Device Selection Table
Part
Number
Output
Osc.
Voltage Package Freq.
(V)* (kHz)
Operating
Temp.
Range
TC115501ECT 5.0 SOT-89-5 100 -40°C to +85°C
TC115331ECT 3.3 SOT-89-5 100 -40°C to +85°C
TC115301ECT 3.0 SOT-89-5 100 -40°C to +85°C
*Other output voltages are available. Please contact
Microchip Technology for details.
Package Type
SOT-89-5
5
GND
NC
1
4
LX
TC115
PS SHDN
23
General Description
The TC115 is a high-efficiency step-up DC/DC
converter for small, low input voltage or battery
powered systems. This device has a start-up voltage of
0.9V and a typical supply current of 80µA. Phase
compensation and soft-start circuitry are included on-
chip. Unlike conventional PWM step-up converters, the
TC115 automatically shifts to pulse frequency
modulation (PFM) at low loads, resulting in reduced
supply current and improved efficiency.
The TC115 requires only an external diode, an
inductor, and a capacitor, and supports typical output
currents of 140mA. Supply current is reduced to less
than 0.5µA, max when SHDN input is brought low.
Small size, low installed cost, and low supply current
make the TC115 step-up converter ideal for use in a
wide range of battery powered systems.
Functional Block Diagram
+
1.5V –
+
C1
10µF
L1
100µH
Sumida
CD-54
D1
5
GND
NC
1
IN5817 +
C2
4 47µF
Tantalum
LX
TC115
PS SHDN
23
+3V
OUT
1.5V to +3V, 50mA Supply
© 2002 Microchip Technology Inc.
DS21361B-page 1
1 page  
4.0 APPLICATIONS
4.1 Input Bypass Capacitors
Using an input bypass capacitor reduces peak current
transients drawn from the input supply and reduces the
switching noise generated by the regulator. The source
impedance of the input supply determines the size of
the capacitor that should be used.
FIGURE 4-1:
TC115 TYPICAL
APPLICATION
VIN +
C1
L1
D1
5
GND
4
LX
TC115
NC PS SHDN
123
+
C2
VOUT
OFF ON
(Tie to VIN or VOUT
if not used)
4.2 Inductor Selection
Selecting the proper inductor value is a trade-off
between physical size and power conversion require-
ments. Lower value inductors cost less, but result in
higher ripple current and core losses. They are also
more prone to saturate since the coil current ramps to
a higher value. Larger inductor values reduce both
ripple current and core losses, but are larger in physical
size and tend to increase the start-up time slightly.
Practical inductor values, therefore, range from 50µH
to 300µH. Inductors with a ferrite core (or equivalent)
are recommended. For highest efficiency, use an
inductor with a series resistance less than 20 mΩ).
TC115
The inductor value directly affects the output ripple
voltage. Equation 4-3 is derived as shown below, and
can be used to calculate an inductor value, given the
required output ripple voltage (VRIPPLE) and output
capacitor series resistance:
EQUATION 4-1:
VRIPPLE ≈ ESR(di)
where ESR is the equivalent series resistance of the
output filter capacitor, and VRIPPLE is in volts.
Expressing di in terms of switch ON resistance and
time:
EQUATION 4-2:
VRIPPLE ≈
ESR [(VIN – VSW)tON]
L
Solving for L:
EQUATION 4-3:
L ≈ ESR [(VIN – VSW)tON]
VRIPPLE
Care must be taken to ensure the inductor can handle
peak switching currents, which can be several times
load currents. Exceeding rated peak current will result
in core saturation and loss of inductance. The inductor
should be selected to withstand currents greater than
IPK (Equation 4-10) without saturating.
Calculating the peak inductor current is straightforward.
Inductor current consists of an AC (sawtooth) current
centered on an average DC current (i.e., input current).
Equation 4-6 calculates the average DC current. Note
that minimum input voltage and maximum load current
values should be used:
EQUATION 4-4:
Output Power
Input Power = Efficiency
© 2002 Microchip Technology Inc.
DS21361B-page 5
5 Page 
TC115
Sales and Support
Data Sheets
Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recom-
mended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following:
1. Your local Microchip sales office
2. The Microchip Corporate Literature Center U.S. FAX: (480) 792-7277
3. The Microchip Worldwide Site (www.microchip.com)
Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using.
New Customer Notification System
Register on our web site (www.microchip.com/cn) to receive the most current information on our products.
2002 Microchip Technology Inc.
DS21361B-page 11
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet TC115.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| TC110 | PFM/PWM Step-Up DC/DC Controller | Microchip |
| TC110 | PFM/PWM Step-Up DC/DC Controller |  Microchip Technology |
| TC1100H | (TC1xxxH) SURFACE MOUNT THYRISTOR SURGE PROTECTIVE DEVICE |  Lite-On Technology |
| TC1100H | (TC1100H - TC1800H) SURFACE MOUNT THYRISTOR SURGE PROTECTIVE DEVICE |  Lite-On |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |