PFM STEP-UP DC/DC REGULATORS
FEATURES
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Space-Saving 5-Pin SOT-23A Package
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Guaranteed 0.9V Start-Up
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PFM (100 KHz Max Operating Frequency)
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40
A Maximum Supply Current (VOUT = 3V @ 30 mA)
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0.5
A Shutdown Mode (TC125)
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Voltage Sense Input (TC126)
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Requires Only Three External Components
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80 mA Maximum Output Current
TYPICAL APPLICATIONS
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Palmtops/PDAs
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Battery-Powered Systems
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Cameras
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Portable Communicators
ORDERING INFORMATION
Part #
Output
Package
Temp.
Voltage
Range
TC125301ECT
3.0V
5-Pin SOT-23A
–40
°C to 85°C
TC125331ECT
3.3V
5-Pin SOT-23A
–40
°C to 85°C
TC125501ECT
5.0V
5-Pin SOT-23A
–40
°C to 85°C
TC126301ECT
3.0V
5-Pin SOT-23A
–40
°C to 85°C
TC126331ECT
3.3V
5-Pin SOT-23A
–40
°C to 85°C
TC126501ECT
5.0V
5-Pin SOT-23A
–40
°C to 85°C
NOTE: Other output voltages are available. Output voltage Range:
2.0V to 7.0V in 0.1V increments. Please contact TelCom
Semiconductor for details.
GENERAL DESCRIPTION
PIN CONFIGURATIONS
TelCom Semiconductor reserves the right to make changes in the circuitry and specifications of its devices.
TC125/6-1 8/3/99
The TC125/6 step-up (Boost) switching regulators fur-
nish output currents to a maximum of 80 mA (VIN = 2V,
VOUT = 3V) with typical efficiencies above 80%. These
devices employ pulse frequency modulation (PFM) for mini-
mum supply current at low loads. They are ideal for battery-
operated applications powered from one or more cells.
Maximum supply current is less than 70
A at full output
load, and less than 5
A in standby (VOUT = 3V). Both
devices require only an external inductor, diode, and capaci-
tor to implement a complete DC/DC regulator.
The TC126 has separate output voltage sensing and
chip power inputs for greater application flexibility. The
TC125 combines the output voltage sensing and chip power
inputs onto a single package pin, but adds a power-saving
shutdown mode that suspends regulator operation and
reduces supply current to less than 0.5
A when the
shutdown control input (SHDN) is low.
Housed in tiny 5-Pin SOT-23A packages, the
TC125/6 occupy minimum board space, and use tiny
external components. The TC125 accepts input voltages
from 2.0V to 10.0V. The TC126 accepts input voltages from
2.2V to 10V. Both the TC125 and TC126 have a guaranteed
start-up voltage of 0.9V at light load.
TC125
TC126
TYPICAL APPLICATION
13
VDD
NC
SHDN
NC
SENSE
TC125
TC126
1
3
5
4
2
5
4
LX
GND
2
PS
1
2
3
4
5
TC125
LX
SHDN
NC
PS
GND
3V
VIN
MA735
47
F/16V
5.0V @ 80mA
SUMIDA
100
H CD54
2 x "AA"
CELL
TANTALUM
Two Cell to 5V Boost Regulator