TC125
TC126
PFM Step-Up DC/DC Regulators
GENERAL DESCRIPTION
FEATURES
■ Space-Saving 5-Pin SOT-23A Package
■ Guaranteed 0.9V Start-Up
■ PFM (100 KHz Max Operating Frequency)
■ 40 µA Maximum Supply Current (VOUT = 3V @ 30 mA)
■ 0.5 µA Shutdown Mode (TC125)
■ Voltage Sense Input (TC126)
■ Requires Only Three External Components
■ 80 mA Maximum Output Current
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 µA at full output
load, and less than 5 µA in standby (VOUT = 3V). Both
devicesrequireonlyanexternalinductor,diode,andcapaci-
tor to implement a complete DC/DC regulator.
The TC126 has separate output voltage sensing and
chip power inputs for greater application flexibility. The
TC125combinestheoutputvoltagesensingandchippower
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 µA when the
shutdown control input (SHDN) is low.
TYPICAL APPLICATIONS
■ Palmtops/PDAs
■ Battery-Powered Systems
■ Cameras
■ Portable Communicators
ORDERING INFORMATION
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.
Part #
Output
Package
Temp.
Range
Voltage
TC125301ECT
TC125331ECT
TC125501ECT
TC126301ECT
TC126331ECT
TC126501ECT
3.0V
3.3V
5.0V
3.0V
3.3V
5.0V
5-Pin SOT-23A –40°C to 85°C
5-Pin SOT-23A –40°C to 85°C
5-Pin SOT-23A –40°C to 85°C
5-Pin SOT-23A –40°C to 85°C
5-Pin SOT-23A –40°C to 85°C
5-Pin SOT-23A –40°C to 85°C
PIN CONFIGURATIONS
GND
4
LX
GND
LX
5
4
5
NOTE: Other output voltages are available. Output voltage Range:
2.0V to 7.0V in 0.1V increments. Please contact Microchip
Technology Inc. for details.
TC126
2
TC125
3
1
1
3
2
NC
NC
PS
SHDN
SENSE
V
DD
TYPICAL APPLICATION
SUMIDA
100µH CD54
MA735
V
IN
5.0V @ 80mA
47 µF/16V
TANTALUM
5
4
LX
GND
2 x "AA"
CELL
3V
TC125
SHDN
1
PS
2
NC
3
Two Cell to 5V Boost Regulator
© 2001 Microchip Technology Inc DS21372A
TC125/6-1 8/3/99
1