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LTC3445EUF#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24
1
LTC3445
3445fa
Buck Regulator
■
High Efficiency: Up to 93%
■
600mA Output Current (V
CC1
= 3V, V
OUT
= 1.3V)
■
Programmable Output Voltage: 0.85V to 1.55V
■
2.5V to 5.5V Input Voltage Range
■
1.5MHz Constant Frequency or Spread Spectrum
Option
■
Soft-Start
LDOs
■
Two LDO Regulators: 0.3V Dropout at 50mA
PowerPath Controller
■
Dynamically Regulates V
CC
BATT
I
2
C
■
Standard (100kHz) or Fast Mode (400kHz)
■
24-Lead (4mm × 4mm) QFN Package
I
2
C Controllable
Buck Regulator with Two LDOs
in a 4mm × 4mm QFN
■
Intel’s Microprocessor Supply (PXA27X)
■
Portable Instruments
, LTC and LT are registered trademarks of Linear Technology Corporation.
The LTC
®
3445 contains a high efficiency monolithic syn-
chronous current mode buck regulator, two LDO regula-
tors, a PowerPath
TM
controller and an I
2
C
TM
interface.
The buck regulator has a 6-bit programmable output range
of 0.85V to 1.55V. Also, the buck regulator uses either a
constant (1.5MHz) or a spread spectrum switching fre-
quency. Using the spread spectrum option allows for a
lower noise regulated output as well as low noise at the
input. In addition, the regulated output voltage slew rate is
programmable via the I
2
C interface.
The LTC3445 contains two LDO voltage regulators. The
regulator output voltages are externally resistor program-
mable. Each LDO is capable of delivering up to 50mA.
The LTC3445 contains control circuitry (PowerPath) for
automatic back-up battery selection. V
BACKUP
is typically
a coin cell.
Typical supply current during operation is only 360µA and
drops to 27µA in shutdown. The 2.5V to 5.5V input
voltage range makes the LTC3445 ideal for single Li-Ion
battery-powered applications. Automatic Burst Mode
®
operation increases efficiency at light loads, further ex-
tending battery life.
Burst Mode is a registered trademark of Linear Technology Corporation.
PowerPath is a trademark of Linear Technology Corporation.
I
2
C is a trademark of Philips Electronics N.V.
Protected by U.S. Patents, including 5481178, 6580258, 6304066, 6127815, 6498466,
6611131, Spread Spectrum patent pending.
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
+
2.2µH
705k
604k
4.7µF
CER
4.7µF
CER
10µF
CER
1.3V
0.85V
TO 1.55V
3V
TYP
V
CC2
GND
LTC3445
V
CC1
nBATT_FAULT
V
CC1
BATTFAULT
4.7µF
CER
V
CC
BATT
V
TRACK
3V
COIN
CELL
V
BACKUP
LDO1
LDO1FB
LDO2
LDO2FB
SW
FB
RUN
SDA
I
2
C BUS
PWR_EN
V
CC1
OR GND
V
CC1
OR GND
SCL
ADD7
ADD6
PGOOD
V
CC
nV
CC
_FAULT
V
CC
20k
3445 TA01
503k
604k
10µF
CER
1.1V
V
BACKUP
20k
V
BACKUP
Efficiency and Power Loss
vs Load Current, V
CC1
= 3.6V
LOAD CURRENT (mA)
30
EFFICIENCY (%)
POWER LOSS (mW)
90
100
20
10
80
50
70
60
40
0.1 10 100 1000
3445 TA01b
0
1
DAC MAX
DAC MIN
DAC MIN
DAC MAX
100
1000
10
1.0
0.1
EFFICIENCY
POWER LOSS
2
LTC3445
3445fa
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
ORDER PART NUMBER
(Note 1)
ABSOLUTE AXI U RATI GS
WWWU
PACKAGE/ORDER I FOR ATIO
UU
W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
LTC3445EUF
T
JMAX
= 125°C, θ
JA
= 37°C/W, θ
JC
= 2.6°C/W
EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB
24 23 22 21 20 19
7 8 9
TOP VIEW
25
UF PACKAGE
24-LEAD (4mm × 4mm) PLASTIC QFN
10 11 12
6
5
4
3
2
1
13
14
15
16
17
18
V
TRACK
V
BACKUP
V
CC1
PGOOD
ADD7
SDA
V
CC
BATT
FB
NC
RUN
SW
NC
LDO2FB
LDO2
V
CC2
LDO1
LDO1FB
BATTFAULT
NC
SCL
ADD6
V
CC1
GND
NC
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC1
= V
CC2
= 3.6V, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
UF PART MARKING
3445
V
CC1
, V
CC2
, SDA, SCL Voltages .................. –0.3V to 6V
RUN, V
TRACK
, V
BACKUP
, PGOOD, ADD7,
ADD6, FB, V
CC
BATT,
BATTFAULT Voltages .............................. –0.3V to V
CC1
SW Voltage ................................ –0.3V to (V
CC1
+ 0.3V)
LDO1FB, LDO2FB Voltages ..................... –0.3V to V
CC2
LDO1, LDO2 Voltages ................ –0.3V to (V
CC2
+ 0.3V)
LDO1, LDO2 Source Current ............................... 50mA
V
CC
BATT Source Current ...................................... 8mA
P-Channel Switch Source Current (DC) ............. 800mA
N-Channel Switch Sink Current (DC) ................. 800mA
Peak SW Sink and Source Current ........................ 1.3A
LDO1, LDO2, V
CC
BATT Output Short-Circuit
Duration.......................................................... Indefinite
Operating Temperature Range (Note 2) ...–40°C to 85°C
Junction Temperature (Note 3)............................ 125°C
Storage Temperature Range ................. –65°C to 125°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
CC1,
V
CC2
Input Voltage Range ● 2.5 5.5 V
RUN Run Threshold ● 0.3 1 1.5 V
PGOOD Reports Undervoltage of any Regulator PGOOD = 0.4V ● 3mA
I
S
DC Bias Current (Shutdown) RUN = 0 27 50 µA
DC Bias Current (Buck, LDO1, LDO2 Disabled) RUN = V
CC1
105 150 µA
Buck Regulator
R
FB
Feedback Resistance 340 kΩ
V
OUT(MIN)
Regulated Output Voltage I
OUT
= 100mA, Burst Mode Operation ● 0.824 0.850 0.875 V
Disabled
V
OUT(MAX)
Regulated Output Voltage I
OUT
= 100mA, Burst Mode Operation ● 1.504 1.55 1.597 V
Disabled
V
OUT(STEP)
Output Voltage Step Size (0 to 48) I
OUT
= 100mA ● 13.1 14.7 16.1 mV
Output Voltage Slew Rate = 00 I
OUT
= 100mA, V
OUT
= 0.85V to 1.55V 11.3 mV/µs
Output Voltage Slew Rate = 01 I
OUT
= 100mA, V
OUT
= 0.85V to 1.55V 7.5 mV/µs
Output Voltage Slew Rate = 10 I
OUT
= 100mA, V
OUT
= 0.85V to 1.55V 3.8 mV/µs
Output Voltage Slew Rate = 11 I
OUT
= 100mA, V
OUT
= 0.85V to 1.55V 0.9 mV/µs
I
PK
Peak Inductor Current V
CC1
= 3V, V
FB
= 0.5V or V
OUT
= 90%, 0.75 1 1.25 A
Duty Cycle < 35%
V
LOADREG
Output Voltage Load Regulation 0.5 %
3
LTC3445
3445fa
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC1
= V
CC2
= 3.6V, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
S
Additional Input DC Bias Current For Buck (Note 4)
Active Mode V
OUT
= 90%, I
LOAD
= 0A 220 µA
Sleep Mode V
OUT
= 103%, I
LOAD
= 0A 6 µA
f
OSC
Nominal Oscillator Frequency V
OUT
= 100% ● 1.2 1.5 1.8 MHz
V
OUT
= 0V 300 kHz
R
PFET
R
DS(ON)
of P-Channel FET I
SW
= 100mA 0.45 Ω
R
NFET
R
DS(ON)
of N-Channel FET I
SW
= –100mA 0.325 Ω
I
LSW
SW Leakage V
RUN
= 0V, V
SW
= 0V or 5V, V
CC1
= 5V 1 µA
LDO1
I
S
Additional DC Bias for LDO1 23 30 µA
V
OUT
Regulated Output Voltage 2.5V < V
IN
< 5.5V, 1mA < I
LOAD
< 50mA 0.582 V
CC2
–V
0.3
Line Regulation ∆V
CC2
= 2.5V to 5.5V, I
LOAD
= 1mA, V
OUT
= 1.2V 1 5 mV
Load Regulation V
CC2
= 2.5V, ∆I
LOAD
= 1mA to 50mA, V
OUT
= 1.2V 15 mV
Dropout Voltage I
LOAD
= 50mA 0.3 V
V
FB
LDO Feedback Voltage I
LOAD
= 0mA ● 0.582 0.6 0.618 V
LDO2
I
S
Additional DC Bias for LDO2 23 30 µA
V
OUT
Regulated Output Voltage 2.5V < V
IN
< 5.5V, 1mA < I
LOAD
< 50mA 0.582 V
CC2
–V
0.3
Line Regulation ∆V
CC2
= 2.5V to 5.5V, I
LOAD
= 1mA, V
OUT
= 1.2V 1 5 mV
Load Regulation V
CC2
= 2.5V, ∆I
LOAD
= 1mA to 50mA, V
OUT
= 1.2V 15 mV
Dropout Voltage I
LOAD
= 50mA 0.3 V
V
FB
LDO Feedback Voltage I
LOAD
= 0mA ● 0.582 0.6 0.618 V
PowerPath Controller
V
TRACK
Tracked Input Voltage 3V
CC1
–V
0.2
V
TRACK
– Tracked Output Voltage at V
CC
BATT 3V < V
TRACK
< V
CC1
– 0.2V –0.2 0 0.2 V
V
CC
BATT
V
BACKUP
Backup Battery Voltage 2 5.5 V
I
BACKUP
Backup Battery Bias Current V
CC1
= V
TRACK
= 0V, V
BACKUP
= 2.5V 4 6.5 µA
V
CC
BATT V
CC
BATT Output V
TRACK
= 0V, V
CC1
= 4V, I
VCCBAT
= 8mA 2.85 3 3.1 V
I
VCCBATT
Max V
CC
BATT Output Current V
CC1
= 2.5V 8 mA
BATTFAULT V
CC1
High Level (Good) Where BATTFAULT Goes High 2.65 2.8 2.9 V
V
CC1
Low Level (Bad) Where BATTFAULT Goes Low 2.4 2.5 2.6 V
Hysteresis V
CC1
= 0V to 4.2V, 4.2 to 0V 0.3 V
I
2
C Interface
f
I2C(MAX)
Maximum I
2
C Operating Frequency (Note 5) 400 kHz
t
BUF
Bus Free Time Between Stop and Start (Note 5) 1.3 µs
Condition
t
HD(RSTA)
Hold Time After (Repeated) (Note 5) 600 ns
Start Condition
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LTC3445EUF#PBF

Mfr. #:
Buy LTC3445EUF#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Controllable Buck Regulator w/ Two LDOs in QFN
Lifecycle:
New from this manufacturer.
Delivery:
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