TK654XX Datasheet, PDF (1/28 Pages) TOKO, Inc – STEP-DOWN CONVERTER WITH BATTERY MONITOR

ADVANCED INFORMATION
TK654xx
ADVANCED
INFORMATION
STEP-DOWN CONVERTER WITH BATTERY MONITOR
FEATURES
s Minimum External Component Count (1 coil, 1 cap)
s Miniature 6 Pin SOT23L-6 Surface Mount Package
s Up To 95% Efficient
s Extremely Low Operating Current (24 µA)
s Low Quiescent Current (18 µA)
s Low Ripple
s Fast Transient Response
s Linear Dropout Characteristics
s Short Circuit Protection
s Regulates Down to 1.8 V
s Synchronous Rectification
s Internal Battery Monitor
DESCRIPTION
The TK654xx low power step-down converter is designed
for portable battery systems, capable of operating from a
single Li-ion battery cell or multiple alkaline or rechargeable
(NiCd or NiMH) battery cells (up to 6 V). The TK654xx
provides the power switch, synchronous rectifier, and the
control circuit for a buck step-down converter. Only two
external components are required to complete the step-
down conversion.
APPLICATIONS
s Battery Powered Systems
s Cellular Telephones
s Pagers
s Personal Communications Equipment
s Radio Controlled Systems
s Toys
Driving the SB pin low will disable the TK654xx and drop
the quiescent current on the input supply to approximately
18 µA.
Pulse Current Amplitude control is used to regulate the
voltage at the V_OUT pin of the IC. When the output voltage
of the TK654xx drops below the regulation threshold, a
current pulse is transferred from the input supply to the
output. The TK654xx utilizes a proprietary control scheme,
where the average amplitude of the current pulse is varied
depending upon the current loads. The proprietary
architecture allows fast transient response and minimal
ripple while maintaining ease-of-use and low component
count.
The TK654xx is available in a miniature 6-pin SOT23L-6
surface mount package.
TK654xxM
The TK654xx provides laser-trimmed output voltages
ranging from 1.8 V to 3.3 V. The low resistance MOSFET
switch and synchronous rectifier allow average currents
up to 200 mA, while maintaining peak efficiencies up to
95%. A low-battery threshold and turn-off threshold can
be individually programmed by the user, utilizing a single
resistor divider connected to the Low Battery Input (LBI)
pin. When the resistively-divided supply voltage on the
LBI pin drops below approximately 1.22 V, the Low Battery
Output (LBO) pin will become asserted. The dual-function
LBI pin can alternatively be used as a Standby (SB) pin.
ORDERING INFORMATION
TK654xxM
Voltage Code
Tape/Reel Code
VOLTAGE CODE
18 = 1.8 V 27 = 2.7 V
21 = 2.1 V 30 = 3.0 V
24 = 2.4 V 33 = 3.3 V
25 = 2.5 V
TAPE/REEL CODE
TL: Tape Left
LBO
VOUT
SW
BLOCK DIAGRAM
VIN
VOUT
LBI/SB
REF
CONTROL
CIRCUIT
OFF
LBO
BATTERY
MONITOR
LBI/SB
GND
VIN
SW
GND
LBO
September 1999 TOKO, Inc.
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