Transcript TPS61251

TPS61251
3.5MHz, 1.5A Current Limit, 92% Efficient Boost Converter for Battery Backu
BOOST CONVERTER FOR BATTERY BACKUP CHARGING WITH
ADJUSTABLE CONSTANT CURRENT AND SNOOZE MODE
Features
Benefits
Resistor programmable input current
limit from 100 to 1500mA with 10%
accuracy @ 500mA
Avoids overloading the source and
gives control over the charge current
of the capacitor
Capable to charge large capacitor
(Farad Range)
Enables back up solution for system
current surge
Snooze mode draws only 2 ́ (typ)
Quiescent Current
Drastic reduction (more than 90%) of
Iq optimizes efficiency and allows
extended battery lifetime
Output voltage up to 6.5 V
Bulk capacitors with higher voltage
rating can be used which implies
bigger amount of energy for a given
capacitance.
1.0 ̈ Inductor & 2x2 QFN package
Smallest solution size C 10x7 mm2
Applications
• Source Current Limited Applications
• Battery Backup Applications
• Li-Ion Applications
• Audio Applications
diagram schematic
TPS61251
3.5MHz, 1.5A current limit, 92% efficient Boost Converter for Battery Backup
Charging
• Resistor Programmable Input Current Limit from 100 to
1500mA with ±10% accuracy @ 500mA
• Avoids overloading the source and gives control
over the charge current of the capacitor
• Designed to charge large capacitor (Farad Range)
• Enables back up solution for system current surge.
• Snooze mode draws only 2 μA (typ) Quiescent
Current
,
• Drastic reduction (more than 90%) of Iq optimizes
efficiency and allows extended battery lifetime.
• Output voltage up to 6.5
V
,
• Bulk capacitors with higher voltage rating can be used
which implies bigger amount of energy for a given
capacitance:
2 E
,
C
• Power Good in
shutdown
,
• 2x2 QFN + 1.0 µH Inductor
(V12  V22 )
• Allows to power the follow-on circuit until the output
voltage is below 2.3V maximizing the use of energy in
the storage capacitor.
• Smallest solution size – 10x7 mm2
• Current limited Applications with high peak current loads
(SSDs, PCMCIA Tx bursts, Memory, GPRS/GSM Tx)
• Battery Backup Applications
• Single cell Li-Ion battery power applications
• Audio applications
RLIM
ILIM = Adjustable
• RF-PA buffer
VIN
ILIM = High limit
( 1.5A )
GN
D
ILIM = Low limit
( 100mA )
TPS61251EVM-517
TPS61251 advantages vs comp
 Vout up to 6.5V
Higher voltage rate bulk capacitors
• Reduces capacitances for a given energy
• Reduces total solution cost.
Energy 
C  ΔV
2
2
C
2 E
(V12  V22 )
 Wider programmable input current range, giving higher flexibility in terms of input energy source.
TPS61251 accuracy is 10% vs 5% from LTC. We guarantee the accuracy for a much wider current
window (100mA to 1500mA vs 200mA to 1000mA)
 Power Good function built in to indicate whether the Vout reaches the programmed value & therefore the
capacitor is fully charged. Operation:
• PG is set high if the feedback voltage reaches 95% of its nominal value.
• The PG comparator operates even in shut down mode when EN is set to low and/or VIN is turned off. This
guaranties power good functionality until the capacitor is discharged.
• The PG output goes low when:
◘ Vout < 2.3 V and indicates the discharge of the capacitor.
◘ Vout < 2.0 V all internal circuitry is disabled. Therefore the PG open drain output becomes high resistive and follows the voltage the
pull-up resistor is connected to.
• While the output capacitors are still charged the converter can be disconnected from its supply but it will still supply
a follow-on circuitry with energy needed for a secured shut down.
Snooze Mode
What is it?
It’s an enhanced power save mode
automatically activated when the load goes
below 2mA.
• Vout with ±2% is maintained
• Iq for this mode is 2uA (typ)
• We achieve this by switching off as many
internal regulation circuits as possible.
• If Iload> 2mA, Vout drops and the converter
wakes up to recharge the cap.
Snooze mode
Allows maximum efficiency over the load range
LTC3125
TPS61251
TPS61252
3.5MHz, 1.5A, 92% Efficient Boost Converter with Adjustable Input Current L
3.5MHz, 1.5A, 92% efficient Boost Converter with
adjustable input current limit
Features
Benefits
Resistor Programmable Input
Current Limit from 100 to 1500mA
with 20% accuracy @ 500mA
Avoids overloading the power source and
eliminates the need for an external load
switch
100% Duty-Cycle Mode When VIN
> VOUT
Output voltage is still regulated if Vin>Vout
Load disconnect
Protects the device from reverse current
Power Good (PG) output with wider
operating window
PG: - High when feedback voltage is 95%
of nominal value. - Low when feedback
voltage falls to 90% of nom. value.
2x2 QFN and 1.0 ̈ Inductor
Smallest solution size C 10x7 mm2
Applications
• USB Host Supplies from a single cell
• Battery Backup Applications
• Current limited applications
• Audio Applications
diagram schematic
TPS61252
3.5MHz, 1.5A, 92% efficient Boost Converter with adjustable input current limit
• Resistor Programmable Input Current Limit from 100 to
1500mA with ±20% accuracy @ 500mA
• Avoids overloading the power source and eliminates
the need for an external load switch.
• 100% Duty-Cycle Mode When VIN > VOUT
• Output voltage is still regulated if Vin>Vout
• Load disconnect
• Protects the device from reverse current
• 2x2 QFN and 1.0 µH Inductor
• Smallest solution size – 10x7 mm2
•
•
•
•
USB Host Supplies from a single cell Li-Ion
Current limited applications
Single cell Li-Ion battery power applications
Audio Applications
TPS61252EVM-667
RLIM
ILIM = Adjustable
VIN
ILIM = High limit
( 1.5A )
TPS61252 advantages vs comp
 Wider programmable input current range, giving higher flexibility in terms of input energy source.
 Wider output voltage range up to 6.5V
 TPS61252 current accuracy is 20% vs 5% from LTC. We guarantee the accuracy for a much wider
current window (100mA to 1500mA vs 200mA to 1000mA)
 Power Good function built in to indicate whether the Vout reaches the programmed value
• PG is set high if the feedback voltage reaches 95% of its nominal value.
• PG is set low when the feedback voltage falls to 90% of its nominal value.
 TPS61252 allows for a smaller total solution size
 TPS61252 has a better output voltage accuracy, ±1.5% vs ±2.4%
TPS61251 & TPS61252 differences
TPS61251 is optimized for charging bulk capacitors
TPS61252 is a regular boost converter.
 TPS61252 current accuracy is 20% vs 10% from TPS61251
 Snooze Mode only available with TPS61251
 Power Good function is different for both devices:
TPS61251
- PG is set high if the feedback voltage reaches 95% of its nominal value.
- The PG comparator operates even in shut down mode when EN is set to low and/or VIN is turned off. This
guaranties power good functionality until the capacitor is discharged.
- The PG output goes low when:
◘ Vout < 2.3 V and indicates the discharge of the capacitor.
◘ Vout < 2.0 V all internal circuitry is disabled. Therefore the PG open drain output becomes high resistive and
follows the voltage the pull-up resistor is connected to.
While the output capacitors are still charged the converter can be disconnected from its supply but it will still supply
a follow-on circuitry with energy needed for a secured shut down.
TPS61252 – As described before