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PDF TK65127M Data sheet ( Hoja de datos )
| Número de pieza | TK65127M | |
| Descripción | STEP-UP VOLTAGE CONVERTER WITH VOLTAGE MONITOR | |
| Fabricantes | TOKO | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de TK65127M (archivo pdf) en la parte inferior de esta página. Total 20 Páginas | ||
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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 VOUT 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
VIN
OSCILLATOR
LOI
VOLTAGE CODE
27 = 2.7 V
30 = 3.0 V
33 = 3.3 V
TAPE/REEL CODE
TL: Tape Left
GND
January 1999 TOKO, Inc.
Page 1
1 page  
TK651xx
TK65127
TYPICAL PERFORMANCE CHARACTERISTICS
OSCILLATOR FREQUENCY VS.
TEMPERATURE
95
90
OUTPUT REGULATION VOLTAGE VS.
TEMPERATURE
2.80
2.75
85 2.70
80
75
-50 0 50 100
TEMPERATURE (°C)
2.65
2.60
-50
0 50
TEMPERATURE (°C)
100
BATTERY CURRENT VS.
INPUT VOLTAGE
120
TA = 25 °C
100 NO LOAD
80
60
40
20
0
0 .5
1 1.5 2
VIN (V)
2.5
3
OUTPUT VOLTAGE VS.
LOAD CURRENT
2.8 L = 95 µH
TOKO P/N: A682AE-014
(3DF SERIES)
TA = 25 °C
2.7
OUTPUT VOLTAGE VS.
LOAD CURRENT
2.8 L = 100 µH
TOKO P/N: A636CY-101M
(D73 SERIES)
TA = 25 °C
2.7
OUTPUT VOLTAGE VS.
LOAD CURRENT
2.8 L = 39 µH
TOKO P/N: A636CY-390M
(D73 SERIES)
TA = 25 °C
2.7
2.6 VIN = 0.9 V 1.3 V
1.1 V 1.6 V
2.5
2.6 VIN = 0.9 V 1.3 V
1.1 V 1.6 V
2.5
2.6 VIN = 0.9 V 1.3 V
1.1 V 1.6 V
2.5
2.4
1
10
IOUT (mA)
100
EFFICIENCY VS. LOAD CURRENT
90
L = 95 µF
Toko P/N: A682AE-014
TA = 25 °C
85 (3DF SERIES) SMALL COIL
80 1.1 V
1.3 V
75
1.6 V
70 VIN = 0.9 V
65
60
0.1
1 10
IOUT (mA)
100
2.4
1
10
IOUT (mA)
100
EFFICIENCY VS. LOAD CURRENT
90 L = 100 µF
Toko P/N: 636CY-101M
TA = 25 °C
85 (D73 SERIES) LARGER COIL 1.1 V
VIN = 0.9 V
80
1.3 V
75 1.6 V
70
65
60
0.1
1 10
IOUT (mA)
100
2.4
1
10
IOUT (mA)
100
MAXIMUM OUTPUT CURRENT VS.
INDUCTOR VALUE (µH)
50
NO PULSE
SKIPPING
40
MODE
TA = 25 °C
30
20
1.1 V
10
1.3 V
VIN = 0.9 V
0
0 40 80
120 160
INDUCTOR VALUE (µH)
January 1999 TOKO, Inc.
Page 5
5 Page 
TK651xx
SINGLE-CELL APPLICATION (CONT.)
The output current of the boost converter comes from the
second half of the input current triangle waveform (averaged
over the period or multiplied by the frequency) given by the
equation:
and:
IOUT = [IPK x t(off)] x f / 2
and:
IPK = (VIN / L) x t(on) = VIN D / f L
where “VIN” is the input voltage, “D” is the on-time duty ratio
of the switch, “f ” is the switching (oscillator) frequency, “L”
is the inductor value, “VOUT” is the output voltage, and “VF”
is the diode forward voltage. It is important to note that
Equation 1 makes the assumption stated in Equation 2:
VIN ≤ (VOUT + VF)(1 - D)
(2)
The implication from Equation 2 is that the inductor will
operate in discontinuous mode.
t(off) = IPK / [(VOUT + VF - VIN) / L]
=(VIN D / f L) / [(VOUT + VF - VIN) / L
= VIN D / f (VOUT + VF - VIN)
therefore:
IOUT = (VIN)2 (D)2 / 2 f L (VOUT + VF - VIN)
which derives Equation 1 of the next section.
INDUCTOR SELECTION
It is under the condition of lowest input voltage that the
boost converter output current capability is the lowest for
a given inductance value. Three other significant
parameters with worst-case values for calculating the
inductor value are: highest switching frequency, lowest
duty ratio (of the switch on-time to the total switching
period), and highest diode forward voltage. Other
parameters which can affect the required inductor value,
but for simplicity will not be considered in this first analysis
are: the series resistance of the DC input source (i.e., the
battery), the series resistance of the internal switch, the
series resistance of the inductor itself, ESR of the output
capacitor, input and output filter losses, and snubber
power loss.
The converter reaches maximum output current capability
when the switch runs at the oscillator frequency, without
pulses being skipped. The output current of the boost
converter is then given by the equation:
IOUT =
(VIN)2 (D)2
(1) 2 f L (VOUT + VF - VIN)
Using worst-case conditions, the inductor value can be
determined by simply transforming the above equation in
terms of “L”:
L(MIN) =
VIN(MIN)2 D(MIN)2
2 f(MAX) IOUT(MAX) [VOUT(MIN) + VF(MAX) - VIN(MIN)]
(3)
where “VF(MAX)” is best approximated by the diode forward
voltage at about two-thirds of the peak diode current value.
The peak diode current is the same as the peak input
current, the peak switch current, and the peak inductor
current. The formula is:
VIN D
IPK = f L
(4)
Some reiteration is implied because “L” is a function of “VF”
which is a function of “IPK” which, in turn, is a function of “L”.
The best way into this loop is to first approximate “VF”,
determine “L”, determine “IPK”, and then determine a new
“VF”. Then, if necessary, reiterate.
When selecting the actual inductor, it is necessary to make
sure that peak current rating of the inductor (i.e., the
current which causes the core to saturate) is greater than
the maximum peak current the inductor will encounter. To
determine the maximum peak current, use Equation 4
again, but use maximum values for “VIN” and “D”, and
minimum values for “f ” and “L”.
It may also be necessary when selecting the inductor to
check the rms current rating of the inductor. Whereas peak
current rating is determined by core saturation, rms current
January 1999 TOKO, Inc.
Page 11
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet TK65127M.PDF ] | |
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