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PDF TC1221 Data sheet ( Hoja de datos )
| Número de pieza | TC1221 | |
| Descripción | (TC1222) High Frequency Switched Capacitor Voltage Converters with Shutdown in SOT Packages | |
| Fabricantes | Microchip Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de TC1221 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
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M TC1221/TC1222
High Frequency Switched Capacitor Voltage Converters
with Shutdown in SOT Packages
Features
• Charge Pumps in 6-Pin SOT-23A Package
• 96% Voltage Conversion Efficiency
• Voltage Inversion and/or Doubling
• Operates from +1.8V to +5.5V
• Up to 25mA Output Current
• Only Two External Capacitors Required
• Power-Saving Shutdown Mode
• Fully Compatible with 1.8V Logic Systems
Applications
• LCD Panel Bias
• Cellular Phones
• Pagers
• PDAs, Portable Data Loggers
• Battery-Powered Devices
Device Selection Table
Part
Number
Package
Osc.
Freq.
(kHz)
Operating
Temp.
Range
TC1221ECH 6-Pin SOT-23A 125 -40°C to +85°C
TC1222ECH 6-Pin SOT-23A 750 -40°C to +85°C
Package Type
6-Pin SOT-23A
C+ SHDN GND
6 54
TC1221ECH
TC1222ECH
1
OUT
2
VIN
3
C–
NOTE: 6-Pin SOT-23A is equivalent to the EIAJ SC-74
General Description
The TC1221/TC1222 are CMOS “charge-pump”
voltage converters in ultra-small 6-Pin SOT-23A
packages. They invert and/or double an input voltage
which can range from +1.8V to +5.5V. Conversion
efficiency is typically 96%. Switching frequency is
125kHz for the TC1221, 750kHz for the TC1222. When
the shutdown pin is held at a logic low, the device goes
into a very low power mode of operation, consuming
less than 1µA of supply current.
For standard voltage inverter applications, the device
requires only two external capacitors. With a few
additional components a positive doubler can also be
built. All other circuitry, including control, oscillator,
power MOSFETs are integrated on-chip. Typical supply
currents are 290µA (TC1221) and 1800µA (TC1222).
All devices are available in 6-pin SOT-23A surface
mount packages.
Functional Block Diagram
Negative Voltage Inverter
C+ VIN
Input
+
C1 TC1221
TC1222
C– ON
SHDN
OFF
GND
OUT
C2
+
V–
Output
2002 Microchip Technology Inc.
DS21367B-page 1
1 page  
4.0 APPLICATIONS INFORMATION
4.1 Output Voltage Considerations
The TC1221/TC1222 perform voltage conversion but
do not provide regulation. The output voltage will droop
in a linear manner with respect to load current. The
value of this equivalent output resistance is approxi-
mately 25Ω nominal at +25°C and VIN = +5V. VOUT is
approximately -5V at light loads, and droops according
to the equation below:
VDROP = IOUT x ROUT
VOUT = – (VIN – VDROP)
4.2 Charge Pump Efficiency
The overall power efficiency of the charge pump is
affected by four factors:
1. Losses from power consumed by the internal
oscillator, switch drive, etc. (which vary with
input voltage, temperature and oscillator
frequency).
2. I2R losses due to the on-resistance of the
MOSFET switches on-board the charge pump.
3. Charge pump capacitor losses due to effective
series resistance (ESR).
4. Losses that occur during charge transfer (from
the commutation capacitor to the output
capacitor) when a voltage difference between
the two capacitors exists.
Most of the conversion losses are due to factors (2) and
(3) above. These losses are given by Equation 4-1(b).
EQUATION 4-1:
a) PLOSS (2, 3) = IOUT2 x ROUT
b) where ROUT = [ 1 / [fOSC(C1) ] + 8RSWITCH +
4ESRC1 + ESRC2]
The 1/(fOSC)(C1) term in Equation 4-1(b) is the
effective output resistance of an ideal switched
capacitor circuit (Figure 4-1 and Figure 4-2). The value
of RSWITCH can be approximated at 0.5Ω for the
TC1221/TC1222.
The remaining losses in the circuit are due to factor (4)
above, and are shown in Equation 4-2. The output
voltage ripple is given by Equation 4-3.
TC1221/TC1222
EQUATION 4-2:
PLOSS(4) = [(0.5)(C1)(VIN2 – VOUT2) + (0.5)
](C2)(VRIPPLE2 – 2VOUT VRIPPLE) x fOSC
EQUATION 4-3:
VRIPPLE = [ IOUT / 2 x ( fOSC) (C2)] + 2 ( IOUT) (ESRC2)
FIGURE 4-1:
f
V+
IDEAL SWITCHED
CAPACITOR MODEL
VOUT
C1 C2 RL
FIGURE 4-2:
EQUIVALENT OUTPUT
RESISTANCE
REQUIV
V+
REQUIV = 1
f x C1
C2
VOUT
RL
4.3 Capacitor Selection
In order to maintain the lowest output resistance and
output ripple voltage, it is recommended that low ESR
capacitors be used. Additionally, larger values of C1
will lower the output resistance and larger values of
C2 will reduce output ripple. (Equation 4-1(b) and
Equation 4-3).
2002 Microchip Technology Inc.
DS21367B-page 5
5 Page 
6.0 PACKAGING INFORMATION
6.1 Package Marking Information
TC1221/TC1222
1 & 2 = part number code + temperature range
(two-digit code)
TC1221/TC1222
TC1221ECH
TC1222ECH
Code
GA
GB
ex: 1221ECH = G A
1222ECH = G B
3 represents year and 2-month code
4 represents production lot ID code
6.2 Taping Form
Component Taping Orientation for 6-Pin SOT-23A (EIAJ SC-74) Devices
User Direction of Feed
Device
Marking
PIN 1
Standard Reel Component Orientation
For TR Suffix Device
(Mark Right Side Up)
Carrier Tape, Number of Components Per Reel and Reel Size
Package
6-Pin SOT-23A
Carrier Width (W)
8 mm
Pitch (P)
4 mm
Part Per Full Reel
3000
Reel Size
7 in
2002 Microchip Technology Inc.
DS21367B-page 11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet TC1221.PDF ] | |
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