DC/DC Converter. LM3248 Datasheet

LM3248 Converter. Datasheet pdf. Equivalent

LM3248 Datasheet
Recommendation LM3248 Datasheet
Part LM3248
Description 2.5A Adjustable Boost-Buck DC/DC Converter
Feature LM3248; LM3248 www.ti.com SNVSA01A – JULY 2013 – REVISED SEPTEMBER 2013 LM3248 2.7 MHz, 2.5A Adjustable B.
Manufacture etcTI
Datasheet
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etcTI LM3248
LM3248
www.ti.com
SNVSA01A – JULY 2013 – REVISED SEPTEMBER 2013
LM3248 2.7 MHz, 2.5A Adjustable Boost-Buck DC/DC Converter
with Boost and Active Current Assist and Analog Bypass (ACB)
Check for Samples: LM3248
FEATURES
1
2 Output Voltage VOUT Adjustable from 0.4V to
4.0V (typ.)
• Input Voltage Range VIN from 2.7V to 5.5V
• Boost-Buck and Buck (Boost-Bypass)
Operating Modes with Seamless Transition
• 2.5A Load Current Capability
• High Conversion Efficiency (> 90% typ.)
• High-Efficiency PFM/PWM Modes with
Seamless Transition
• Very Fast Transient Response: 10 µs
• ACB Reduces Inductor Size Requirements
• Dither to aid RX Band Noise Compliance
APPLICATIONS
• Multi-mode 2G/3G/4G and 3GPP/LTE Smart-
phones and Tablets
• Hand-Held Radios
• RF Mobile Devices
DESCRIPTION
The LM3248 is a PWM/PFM Boost-Buck DC/DC
converter that provides efficient utilization of battery
power over a wide voltage range. The device
architecture is suitable for advanced RF front-end
systems that demand dynamic voltage and current to
support converged power amplifier architectures
operating in 2G/3G/4G and 3GPP/LTE modes. For
example, the LM3248 is designed to produce higher
output voltages while maintaining PFM mode as
required by some new reduced-power CMOS PAs.
The extremely fast Boost-Buck function reduces RF
PA overhead power dissipation, extending battery talk
time. The device will operate at input voltage VIN
range of 2.7V to 5.5V and an adjustable output
voltage VOUT range of 0.4V to 4.0V at a maximum
current load of 2.5A.
The LM3248 is available in a 30-bump, lead-free thin
DSBGA package.
Typical Application Diagram
1.0 H
10 F
1 F Low ESL
VBATT
2.7V to 5.5V
10 F
SW_
BOOST
OUT_
BOOST
PVIN_
BOOST
VDD_
BOOST
BYPASS
BOOST
PVIN_
BUCK
VDD1_
BUCK
VDD2_
BUCK
FB_
BUCK
ACB
BUCK
ACB
SW_
BUCK
1.5 H
10 F
CONTROL
SGND_
BOOST_
SGND_
BOOST DGND ENABLE GATE MODE BUCK
VCON
FB
1 nF
VCC_PA
Apps
Processor
1.8V Logic
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2013, Texas Instruments Incorporated



etcTI LM3248
LM3248
SNVSA01A – JULY 2013 – REVISED SEPTEMBER 2013
www.ti.com
DESCRIPTION (CONTINUED)
The LM3248 utilizes step-up (Boost) and variable output step-down (Buck) DC/DC converters. Combining a
cascaded Boost and Buck converter in a single package is ideal for powering the latest multimode/multi-standard
RF power amplifiers. The Boost converter provides the RF power subsystem the capability to operate at lower
battery voltages as well as to maintain increased PA linearity and transmit power margins over a wider battery
voltage supply range.
The Buck has a unique Active Current assist and analog Bypass (ACB) feature to minimize inductor size without
any loss of output regulation for the entire battery voltage and RF output power range, until dropout. ACB
provides a parallel current path, when needed, to limit the maximum inductor current while still driving a 2.5A
load. The LM3248 may also be configured as a Buck-only converter with a boost bypass feature to enable
highest efficiency operation with minimal dropout voltage when the Boost is not needed.
The LM3248 automatically and seamlessly transitions between Pulse Width Modulation (PWM) and Pulse
Frequency Modulation (PFM) modes for high-efficiency operation with both full and light load conditions.
Connection Diagram
A VDD_
BOOST
PVIN_
BOOST
PVIN_
BOOST
OUT_
BOOST
OUT_
BOOST
B BOOST_
GATE
SGND_
BOOST
SW_
BOOST
SW_
BOOST
SW_
BOOST
C MODE
VDD1_
BUCK
SGND_
BUCK
PGND
PGND
D ENABLE
VCON
NC
SW_
BUCK
SW_
BUCK
E ATB1
FB_
BUCK
DGND
PVIN_
BUCK
PVIN_
BUCK
F ATB2
VDD2_
BUCK
BGND
ACB
ACB
1 2 3 45
Figure 1. 30-Bump Thin DSBGA Package (0.4 mm pitch)
(Top View, bumps down)
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Product Folder Links: LM3248
Copyright © 2013, Texas Instruments Incorporated



etcTI LM3248
LM3248
www.ti.com
SNVSA01A – JULY 2013 – REVISED SEPTEMBER 2013
Pin #
A1
A2
A3
A4
A5
B1
B2
B3
B4
B5
C1
C2
C3
C4
C5
D1
D2
D3
D4
D5
E1
E2
E3
E4
E5
F1
F2
F3
F4
F5
Name
VDD_BOOST
PVIN_BOOST
OUT_BOOST
BOOST_GATE
SGND_BOOST
SW_BOOST
MODE
VDD1_BUCK
SGND_BUCK
PGND
ENABLE
VCON
NC
SW_BUCK
ATB1
FB_BUCK
DGND
PVIN_BUCK
ATB2
VDD2_BUCK
BGND
ACB
Pin Descriptions
I/O Description
- Power supply voltage input for Boost Analog blocks. Connected to VBATT supply.
- Power supply voltage input for Boost Bypass FET.
Boost converter output. When Boost and Buck are active, OUT_BOOST must be externally
O
connected to PVIN_BUCK. A 10 µF capacitor must be placed between this node and GND.
Internally connected to BUCK voltage input and feedback to inverting input of Boost error
amplifier.
I
Digital input. A Low-to-High transition wakes up the boost converter and positions it to a high
level in preparation for a possible VCON change.
- Analog Ground for the Boost Analog blocks.
I/O
Boost converter switch node. When Boost and Buck are active, SW_BOOST is typically
connected to VBATT supply through external power inductor.
I Digital input. Low = 3G/4G (PWM/PFM) operation; High = 2G (PWM only) operation.
Power supply voltage input for Buck Analog PWM blocks. Internally connected to PVIN_BUCK
when used with Boost. If Buck-only mode is used then must be directly connected to VBATT
supply.
- Analog Ground for the Buck Analog Blocks.
- Power Ground for output FETs.
I
Input. Chip enable. Setting ENABLE = High biases up the Buck and initiates VCON regulation
by the Buck.
I Analog voltage control input which controls Buck output voltage.
- No connect; leave this pin floating.
O Buck converter switch node for external filter inductor connection.
- Test pin. Connect to SGND or System Ground.
-
Feedback input to inverting input of error amplifier. Connect Buck output voltage directly to this
node.
- Ground for Boost, Buck, and RFFE digital blocks.
-
Power supply input for Buck PFET and ACB FET. A 10 µF capacitor must be placed between
this node and PGND. Must be externally connected to OUT_BOOST.
- Test pin. Connect to SGND or System Ground.
-
Power supply voltage input for Buck Analog PWM blocks. Internally connected to PVIN_BUCK
when used with Boost.
- Ground for ACB bypass circuit.
-
Active Current assist and Bypass output. Connected to the Buck converter output filter
capacitor.
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
Copyright © 2013, Texas Instruments Incorporated
Product Folder Links: LM3248
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