LTC3558
Linear USB Battery Charger
with Buck and
Buck-Boost Regulators
FEATURES
Battery Charger
n
Standalone USB Charger
n
Up to 950mA Charge Current Programmable via
Single Resistor
n
HPWR Input Selects 20% or 100% of Programmed
Charge Current
n
NTC Input for Temperature Qualified Charging
n
Internal Timer Termination
n
Bad Battery Detection
Switching Regulators (Buck and Buck-Boost)
n
Up to 400mA Output Current per Regulator
n
2.25MHz Constant-Frequency Operation
n
Power Saving Burst Mode
®
Operation
n
Low Profile, 20-Lead, 3mm
×
3mm QFN Package
DESCRIPTION
The LTC
®
3558 is a USB battery charger with dual high ef-
ficiency switching regulators. The device is ideally suited
to power single-cell Li-Ion/Polymer based handheld ap-
plications needing multiple supply rails.
Battery charge current is programmed via the PROG pin
and the HPWR pin with capability up to 950mA of current
at the BAT pin. The
CHRG
pin allows battery status to be
monitored continuously during the charging process. An
internal timer controls charger termination.
The part includes monolithic synchronous buck and buck-
boost regulators that can provide up to 400mA of output
current each and operate at efficiencies greater than 90%
over the entire Li-Ion/Polymer battery range. The buck-
boost regulator can regulate its programmed output voltage
at its rated deliverable current over the entire Li-Ion range
without drop out, increasing battery runtime.
The LTC3558 is offered in a low profile (0.75mm), thermally
enhanced, 20-lead (3mm
×
3mm) QFN package.
, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners.
APPLICATIONS
n
n
SD/Flash-Based MP3 Players
Low Power Handheld Applications
TYPICAL APPLICATION
USB Charger Plus Buck Regulator and Buck-Boost Regulator
USB (4.3V TO 5.5V)
1μF
1.74k
PROG
NTC
LTC3558
CHRG
SUSP
DIGITAL
CONTROL
HPWR
MODE
EN1
EN2
FB2
105k
EXPOSED
PAD
15k
330pF
V
C2
3558 TA01
Demo Board
V
CC
BAT
PV
IN1
PV
IN2
10μF
+
SINGLE
Li-lon CELL
(2.7V TO 4.2V)
1.2V AT 400mA
SW1
FB1
SWAB2
4.7μH
324k
649k
10pF
10μF
2.2μH
3.3V AT 400mA
SWCD2
V
OUT2
324k
121k
33pF
22μF
10pF
GND
3558f
1
LTC3558
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
HPWR
15 EN2
14 V
C2
21
13 FB2
12 SUSP
11 V
OUT2
6
SW1
7
PV
IN1
8
PV
IN2
9 10
SWAB2
SWCD2
CHRG
PROG
NTC
V
CC
GND 1
BAT 2
MODE 3
FB1 4
EN1 5
V
CC
(Transient);
t < 1ms and Duty Cycle < 1%....................... –0.3V to 7V
V
CC
(Static) .................................................. –0.3V to 6V
BAT, CHRG ................................................... –0.3V to 6V
PROG, SUSP .................................–0.3V to (V
CC
+ 0.3V)
HPWR, NTC................... –0.3V to Max (V
CC
, BAT) + 0.3V
PROG Pin Current ...............................................1.25mA
BAT Pin Current ..........................................................1A
PV
IN1
, PV
IN2
..................................–0.3V to (BAT + 0.3V)
EN1, EN2, MODE, V
OUT2
.............................. –0.3V to 6V
FB1, SW1 ......................... –0.3V to (PV
IN1
+ 0.3V) or 6V
FB2, V
C2
, SWAB2 ............. –0.3V to (PV
IN2
+ 0.3V) or 6V
SWCD2 ............................–0.3V to (V
OUT2
+ 0.3V) or 6V
I
SW1
...............................................................600mA DC
I
SWAB2
, I
SWCD2
, I
VOUT2
...................................750mA DC
Junction Temperature (Note 2) ............................. 125°C
Operating Temperature Range (Note 3).... –40°C to 85°C
Storage Temperature.............................. –65°C to 125°C
20 19 18 17 16
UD PACKAGE
20-LEAD (3mm
×
3mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 68°C/W
EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3558EUD#PBF
TAPE AND REEL
LTC3558EUD#TRPBF
PART MARKING
LDCD
PACKAGE DESCRIPTION
20-Lead (3mm
×
3mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
3558f
2
LTC3558
ELECTRICAL CHARACTERISTICS
SYMBOL
V
CC
I
VCC
V
FLOAT
I
CHG
I
BAT
PARAMETER
Input Supply Voltage
Battery Charger Quiescent Current
(Note 4)
BAT Regulated Output Voltage
Constant-Current Mode Charge
Current
Battery Drain Current
Standby Mode, Charge Terminated
Suspend Mode, V
SUSP
= 5V
0°C ≤ T
A
≤ 85°C
l
HPWR = 1
HPWR = 0
Standby Mode, Charger Terminated, EN1 = EN2 = 0
Shutdown, V
CC
< V
UVLO
, BAT = 4.2V, EN1 = EN2 = 0
Suspend Mode, SUSP = 5V, BAT = 4.2V, EN1 = EN2 = 0
V
CC
= 0V, EN1 = EN2 = 1, MODE = 1,
FB1 = FB2 = 0.85V, V
OUT2
= 3.6V
BAT = 3.5V, V
CC
Rising
BAT = 3.5V
BAT = 4.05V, (V
CC
– BAT) Falling
BAT = 4.05V
HPWR = 1
HPWR = 0
BAT < V
TRKL
BAT < V
TRKL
BAT Rising
Threshold Voltage Relative to V
FLOAT
BAT Falling
BAT = V
FLOAT
BAT < V
TRKL
I
BAT
Falling
I
BAT
= 190mA
3.5
0.4
0.085
36
2.8
–75
30
4.179
4.165
440
84
Battery Charger
l
The
l
denotes specifications that apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, BAT = PV
IN1
= PV
IN2
= 3.6V, R
PROG
= 1.74k, unless otherwise noted.
CONDITIONS
MIN
4.3
285
8.5
4.200
4.200
460
92
–3.5
–2.5
–1.5
–50
4
200
50
130
1.000
0.200
0.100
800
46
2.9
100
–95
1.7
4
0.5
0.1
2.2
500
105
4.5
0.6
0.11
–115
56
3
70
TYP
MAX
5.5
400
17
4.221
4.235
500
100
–7
–4
–3
–100
4.125
UNITS
V
μA
μA
V
V
mA
mA
μA
μA
μA
μA
V
mV
mV
mV
V
V
V
mA/mA
mA
V
mV
mV
ms
Hour
Hour
mA/mA
ms
mΩ
°C
V
UVLO
ΔV
UVLO
V
DUVLO
ΔV
DUVLO
V
PROG
h
PROG
I
TRKL
V
TRKL
ΔV
TRKL
ΔV
RECHRG
t
RECHRG
t
TERM
t
BADBAT
h
C/10
t
C/10
R
ON(CHG)
T
LIM
NTC
V
COLD
V
HOT
V
DIS
I
NTC
Undervoltage Lockout Threshold
Undervoltage Lockout Hysteresis
Differential Undervoltage Lockout
Threshold
Differential Undervoltage Lockout
Hysteresis
PROG Pin Servo Voltage
3.85
Ratio of I
BAT
to PROG Pin Current
Trickle Charge Current
Trickle Charge Threshold Voltage
Trickle Charge Hysteresis Voltage
Recharge Battery Threshold Voltage
Recharge Comparator Filter Time
Safety Timer Termination Period
Bad Battery Termination Time
End-of-Charge Comparator Filter Time
Battery Charger Power FET On-
Resistance (Between V
CC
and BAT)
Junction Temperature in Constant
Temperature Mode
Cold Temperature Fault Threshold
Voltage
Hot Temperature Fault Threshold
Voltage
NTC Disable Threshold Voltage
NTC Leakage Current
End-of-Charge Indication Current Ratio (Note 5)
Rising NTC Voltage
Hysteresis
Falling NTC Voltage
Hysteresis
Falling NTC Voltage
Hysteresis
V
NTC
= V
CC
= 5V
75
33.4
l
0.7
–1
76.5
1.6
34.9
1.6
1.7
50
78
36.4
2.7
1
%V
CC
%V
CC
%V
CC
%V
CC
%V
CC
mV
μA
3558f
3
LTC3558
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IL
V
IH
R
DN
V
CHRG
I
CHRG
PV
IN1
I
PVIN1
PARAMETER
Input Low Voltage
Input High Voltage
Logic Pin Pull-Down Resistance
CHRG
Pin Output Low Voltage
CHRG
Pin Input Current
Input Supply Voltage
Pulse Skip Input Current
Burst Mode Current
Shutdown Current
Supply Current in UVLO
PV
IN1
Falling
PV
IN1
Rising
Switching Frequency
Peak PMOS Current Limit
Feedback Voltage
FB Input Current
Maximum Duty Cycle
R
DS(ON)
of PMOS
R
DS(ON)
of NMOS
SW Pull-Down in Shutdown
Input Supply Voltage
PWM Input Current
Burst Mode Input Current
Shutdown Current
Supply Current in UVLO
PV
IN2
Falling
PV
IN2
Rising
Minimum Regulated Buck-Boost V
OUT
Maximum Regulated Buck-Boost V
OUT
Forward Current Limit (Switch A)
Forward Current Limit (Switch A)
Reverse Current Limit (Switch D)
Maximum Deliverable Output Current
in Burst Mode Operation
Feedback Servo Voltage
FB2 Input Current
Switching Frequency
MODE = 0
MODE = 1
MODE = 0
MODE = 1
2.7V < PV
IN2
< 4.2V
2.75V < V
OUT2
< 5.5V
l
l
l
l
l
l
The
l
denotes specifications that apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, BAT = PV
IN1
= PV
IN2
= 3.6V, R
PROG
= 1.74k, unless otherwise noted.
CONDITIONS
HPWR, SUSP MODE, EN1, EN2 Pins
,
HPWR, SUSP MODE, EN1, EN2 Pins
,
HPWR, SUSP Pins
I
CHRG
= 5mA
BAT = 4.5V, V
CHRG
= 5V
l
l
MIN
TYP
MAX
0.4
UNITS
V
V
MΩ
mV
μA
V
μA
μA
μA
μA
V
V
MHz
mA
mV
nA
%
Ω
Ω
kΩ
Logic (HPWR, SUSP
CHRG,
EN1, EN2, MODE)
,
1.2
1.9
4
100
0
2.7
220
35
0
4
2.45
2.55
2.25
800
800
6.3
250
1
4.2
400
50
2
8
2.70
2.59
1050
820
50
0.65
0.75
13
2.7
220
20
0
4
2.45
2.55
2.65
5.60
700
250
450
0
820
320
575
35
4.2
400
30
1
8
2.70
2.75
Buck Switching Regulator
FB1 = 0.85V, MODE = 0 (Note 6)
FB1 = 0.85V, MODE = 1 (Note 6)
EN1 = 0
PV
IN1
= PV
IN2
= 2V
l
l
l
PV
IN1
UVLO
f
OSC
I
LIMSW1
V
FB1
I
FB1
D
MAX1
R
PMOS1
R
NMOS1
R
SW1(PD)
PV
IN2
I
PVIN2
2.30
1.91
550
MODE = 0
MODE = 0
FB1 = 0.85V
FB1 = 0V
I
SW1
= 100mA
I
SW1
= –100mA
l
l
780
–50
100
Buck-Boost Switching Regulator
V
μA
μA
μA
μA
V
V
V
V
mA
mA
mA
mA
mA
800
2.25
820
50
2.59
mV
nA
MHz
MODE = 0, I
OUT
= 0A, FB2 = 0.85V (Note 6)
MODE = 1, I
OUT
= 0A, FB2 = 0.85V (Note 6)
EN2 = 0, I
OUT
= 0A
PV
IN1
= PV
IN2
= 2V
l
l
PV
IN2
UVLO
V
OUT2(LOW)
V
OUT2(HIGH)
I
LIMF2
I
PEAK2(BURST)
I
LIMR2
I
MAX2(BURST)
V
FB2
I
FB2
f
OSC
2.30
5.45
580
180
325
–35
50
780
–50
1.91
I
ZERO2(BURST)
Reverse Current Limit (Switch D)
FB2 = 0.85V
MODE = 0
3558f
4
LTC3558
ELECTRICAL CHARACTERISTICS
SYMBOL
R
DSP(ON)
R
DSN(ON)
I
LEAK(P)
I
LEAK(N)
DC
BUCK(MAX)
t
SS2
R
OUT(PD)
PARAMETER
PMOS R
DS(ON)
NMOS R
DS(ON)
PMOS Switch Leakage
NMOS Switch Leakage
Maximum Buck Duty Cycle
Soft-Start Time
V
OUT
Pull-Down in Shutdown
Switches A, D
Switches B, C
MODE = 0
MODE = 0
l
The
l
denotes specifications that apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, BAT = PV
IN1
= PV
IN2
= 3.6V, R
PROG
= 1.74k, unless otherwise noted.
CONDITIONS
V
OUT
= 3.6V
–1
–1
100
75
0.5
10
MIN
TYP
0.6
0.6
1
1
MAX
UNITS
Ω
Ω
μA
μA
%
%
ms
kΩ
DC
BOOST(MAX)
Maximum Boost Duty Cycle
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
T
J
= T
A
+ (P
D
•
θ
JA
)
Note 3:
The LTC3558E is guaranteed to meet specifications from 0°C to
85°C. Specifications over the –40°C to 85°C operating temperature range
are assured by design, characterization and correlation with statistical
process controls.
Note 4:
V
CC
supply current does not include current through the PROG pin
or any current delivered to the BAT pin. Total input current is equal to this
specification plus 1.00125 • I
BAT
where I
BAT
is the charge current.
Note 5:
I
C/10
is expressed as a fraction of measured full charge current
with indicated PROG resistor.
Note 6:
Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
3558f
5
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