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PDF TK652XX Data sheet ( Hoja de datos )
| Número de pieza | TK652XX | |
| 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 TK652XX (archivo pdf) en la parte inferior de esta página. Total 20 Páginas | ||
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ADVANACDEVDAINNCFOEDRMINAFTOIORNMATION
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
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
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
Vref UVLO
LBI
TK652xxM
Voltage Code
Tape/Reel Code
VIN
CONTROL
CIRCUIT
OSCILLATOR
LOI
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
Page 1
1 page  
ADVANCED INFORMATION
TK652xx
TK65218
TYPICAL PERFORMANCE CHARACTERISTICS
OSCILLATOR FREQUENCY VS.
TEMPERATURE
91
OUTPUT REGULATION VOLTAGE VS.
TEMPERATURE
1.800
87 1.795
83 1.790
79
75
-50
0 50
TEMPERATURE (°C)
100
1.785
1.780
-50
0 50
TEMPERATURE (°C)
100
BATTERY CURRENT VS.
INPUT VOLTAGE
200
TA = 25 °C
160 NO LOAD
120
80
40
0
0.1 0.5 1.0 1.5
VIN (V)
OUTPUT VOLTAGE VS.
LOAD CURRENT
1.9 L = 95 µH
TOKO P/N: A682AE-014
(3DF SERIES)
TA = 25 °C
1.8
1.7 VIN = 0.9 V 1.3 V
1.6 V
1.6 1.1 V
OUTPUT VOLTAGE VS.
LOAD CURRENT
1.9 L = 100 µH
TOKO P/N: 636CY-101M
(D73F SERIES)
TA = 25 °C
1.8
1.7 VIN = 0.9 V 1.3 V
1.6 V
1.6 1.1 V
OUTPUT VOLTAGE VS.
LOAD CURRENT
1.9 L = 39 µH
TOKO P/N: 636CY-390M
(D73 SERIES)
TA = 25 °C
1.8
VIN = 0.9 V
1.3 V
1.7
1.6 V
1.1 V
1.6
1.5
1
10
IOUT (mA)
100
EFFICIENCY VS. LOAD CURRENT
80 L = 95 µF
TOKO P/N: A682AE-014
TA = 25 °C
75 (3DF SERIES) SMALL COIL
1.6 V
70
65
1.1 V
60
VIN = 0.9 V
55
1.3 V
50
0.1
1 10
IOUT (mA)
100
January 1999 TOKO, Inc.
1.5
1
10
IOUT (mA)
100
EFFICIENCY VS. LOAD CURRENT
85
TA = 25 °C
80
1.6 V
75
70 VIN = 0.9 V
1.3 V
65 1.1 V
60
55
0.1
L = 100 µF
TOKO P/N: A636CY-101M
(D73 SERIES) LARGER COIL
1 10 100
IOUT (mA)
1.5
1
10
IOUT (mA)
100
MAXIMUM OUTPUT CURRENT VS.
INDUCTOR VALUE
100
NO PULSE
SKIPPING
80 MODE
TA = 25 °C
60
1.3
40
1.1 V
20
1.6 V
0 VIN = 0.9 V
0 40 80
120 160
INDUCTOR VALUE (µH)
Page 5
5 Page 
ADVANCED INFORMATION
TK652xx
SINGLE-CELL APPLICATION (CONT.)
second half of the input current triangle waveform (averaged
over the period or multiplied by the frequency) given by the
equation:
IOUT = [IPK x t(off)] x f / 2
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:
and:
IPK = (VIN / L) x t(on) = VIN D / f L
VIN ≤ (VOUT + VF)(1 - D)
(2)
and:
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)
The implication from Equation ) is that the inductor will
operate in discontinuous mode.
Now, plugging in 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)]
which derives Equation 1 of the next section.
(3)
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)
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 the 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, using the 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
January 1999 TOKO, Inc.
Page 11
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet TK652XX.PDF ] | |
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