TK65025 Datasheet, PDF (1/12 Pages) TOKO, Inc – STEP-UP VOLTAGE CONVERTER WITH VOLTAGE MONITOR

TK65025
STEP-UP VOLTAGE CONVERTER WITH VOLTAGE MONITOR
FEATURES
APPLICATIONS
s Guaranteed 0.9 V Operation
s Battery Powered Systems
s Very Low Quiescent Current
s Cellular Telephones
s Internal Bandgap Reference
s Pagers
s High Efficiency MOS Switching
s Personal Communications Equipment
s Low Output Ripple
s Portable Instrumentation
s Microprocessor Reset Output
s Portable Consumer Equipment
s Laser-Trimmed Output Voltage
s Radio Control Systems
s Laser-Trimmed Oscillator
s Undervoltage Lockout
s Regulation by Pulse Burst Modulation (PBM)
2
DESCRIPTION
The TK65025 Low Power Step-Up DC-DC converter is
designed for portable battery-powered systems, capable
of operating from a single battery cell down to 0.9 V. The
TK65025 provides the power switch and the control circuit
for a boost converter. The converter takes a DC input and
boosts it up to 3 volts. This regulated 3 volt output is
typically used to supply power to a microprocessor-con-
trolled system.
The output voltage is laser-trimmed to 3.0 V. An
internal detector monitors the output voltage and provides
an active-low microprocessor reset signal whenever the
output voltage falls below an internally preset limit. An
internal undervoltage lockout circuit is utilized to prevent
the inductor switch from remaining in the "ON" mode when
the battery voltage is too low to permit normal operation.
Pulse burst modulation (PBM) is used to regulate the
voltage at the V_OUT pin at the IC. PBM is the process in
which an oscillator signal is gated or not gated to the switch
drive each period. The decision is made just before the
start of each cycle and is based on comparing the output
voltage to an internally-generated bandgap reference. The
decision is latched, so the duty ratio is not modulated within
a cycle. The average duty ratio is effectively modulated by
the "bursting" and skipping of pulses which can be seen at
the IND pin of the IC. Special care has been taken to
ORDERING INFORMATION
TK65025M
Tape/Reel Code
achieve high reliability through the use of Oxide, double
Nitride passivation. The TK65025 is available in a very
small plastic surface mount package. (SOT-23L)
Customized levels of accuracy in oscillator frequency
and output voltage are available.
TK65025M
VIN 1
M25
GND 2
IND 3
6 _RESET
5 _GND
4 VOUT
IND
3
VIN ₁
BLOCK DIAGRAM
V_REF
CONT ROL
CIRCUIT
RC OSC.
VOUT
4
UVLO
6 ^RESET
February, 1997 Toko, Inc.
TAPE/REEL CODE
BX : Bulk/Bag
TL : Tape Left
2,5
GND
Page 1