TK652XX Datasheet, PDF (1/20 Pages) TOKO, Inc – STEP-UP VOLTAGE CONVERTER WITH VOLTAGE MONITOR

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TK652xx
STEP-UP VOLTAGE CONVERTER WITH VOLTAGE MONITOR
FEATURES
APPLICATIONS
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 Laser-Trimmed Output Voltage
s Low Output Voltage Monitor
s Low Battery Monitor
s Undervoltage Lockout
s Regulation by Pulse Burst Modulation (PBM)
DESCRIPTION
The TK652xx 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
TK652xx 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 1.8, 2.1, or 2.4 V.
The output voltage is laser-trimmed. Two internal detectors
monitor the output voltage and battery voltage. The Low
Output Indicator (LOI) generates an active low when the
battery voltage falls below 90 % of the output voltage. The
Low Battery Indicator (LBI) generates an active low when
the battery voltage falls below 1.1 V. These outputs can be
used to notify the microprocessor or power monitor circuit
of a fault condition. 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
ORDERING INFORMATION
s Battery Powered Systems
s Cellular Telephones
s Pagers
s Personal Communications Equipment
s Portable Instrumentation
s Portable Consumer Equipment
s Radio Control Systems
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
SW pin of the IC. Special care has been taken to achieve
high reliability through the use of Oxide, double Nitride
passivation. The TK652xx is available in a miniature
SOT-23L-6 surface mount package.
Customized levels of accuracy in oscillator frequency and
output voltage are available.
TK652xx
VIN
LOI
20P
LBI
GND
SW
VOUT
BLOCK DIAGRAM
SW
VOUT
LBI
Vref
UVLO
TK652xxM
CONTROL
CIRCUIT
LOI
Tape/Reel Code
VIN
Voltage Code
OSCILLATOR
VOLTAGE CODE
18 = 1.8 V
21 = 2.1 V
24 = 2.4 V
January 1999 TOKO, Inc.
TAPE/REEL CODE
TL: Tape Left
GND
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