TK651XX Datasheet, PDF (1/20 Pages) TOKO, Inc – STEP-UP VOLTAGE CONVERTER WITH VOLTAGE MONITOR

TK651xx
STEP-UP VOLTAGE CONVERTER WITH VOLTAGE MONITOR
FEATURES
s Guaranteed 0.9 V Operation
s Very Low Quiescent Current
s Internal Bandgap Reference
s High Efficiency MOS Switching
s Low Output Ripple
s Microprocessor Reset Output
s Laser-Trimmed Output Voltage
s Laser-Trimmed Oscillator
s Undervoltage Lockout
s Regulation by Pulse Burst Modulation (PBM)
APPLICATIONS
s Battery Powered Systems
s Cellular Telephones
s Pagers
s Personal Communications Equipment
s Portable Instrumentation
s Portable Consumer Equipment
s Radio Control Systems
DESCRIPTION
The TK651xx 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
TK651xx provides the power switch and the control circuit
for a boost converter. The converter takes a DC input and
boosts it up to a regulated 2.7, 3.0 or 3.3 V output .
The output voltage is laser-trimmed. A Low Output Indicator
detector (LOI) 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 (UVLO) 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 of 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
ORDERING INFORMATION
TK651xxM
Voltage Code
Tape/Reel Code
pulses which can be seen at the SW pin of the IC. Special
care should be taken to achieve reliability through the use
of Oxide, double Nitride passivation. The TK651xx is
available in a miniature 6-pin SOT-23L-6 surface mount
package.
Customized levels of accuracy in oscillator frequency and
output voltage are available.
TK651xx
VIN
LOI
20P
GND
GND
SW
VOUT
BLOCK DIAGRAM
SW
VOUT
Vref
UVLO
CONTROL
CIRCUIT
LOI
VIN
OSCILLATOR
VOLTAGE CODE
TAPE/REEL CODE
27 = 2.7 V
TL: Tape Left
30 = 3.0 V
GND
33 = 3.3 V
January 1999 TOKO, Inc.
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