BL8578

BL8578
Max.1.6A Li-ion Switching Charger IC
DESCRIPTION
FEATURES
The BL8578 is a 1.6A Li-Ion battery switching
charger intended for 5V adapters. Low power
dissipation, an internal MOSFET and its compact
package with minimum external components
requirement makes the BL8578 ideal for portable
applications. The BL8578 includes complete
charge termination circuitry, automatic recharge
and a ±1% 4.2V/4.35V float voltage.



Very Low Power Dissipation
1.6A Maximum Charge Current
Standalone Capability with no Requirement
of External MOSFET, Sense Resistor or
Blocking Diode
Constant-Current/Constant-Voltage Operation
with Thermal Regulation to Maximize Charge
Rate Without Risk of Overheating
Charges Single Cell Li-Ion Batteries Directly
from USB Port
Drainage Charge Current Thermal Regulation
Status Outputs for LED or System Interface
Optional Battery Temperature Monitoring
Before and During Charge Automatic Sleep
Mode for Low-Power
Preset 4.2V/4.35V float Voltage with ±1%
Accuracy
Automatic Recharge
Available in DFN3x3-10L Package
RoHS Compliant and 100% Lead (Pb)-Free


External sense resistor and Reverse diode is not
need. Build-in thermal feedback mechanism
regulates the charge current to control the die
temperature during high power operation or at
elevated ambient temperature.


Battery charge current, charge timeout and endof-charge indication parameters can program by
external components. Additional features include
shorted cell detection and overvoltage protection.




The BL8578 is available in DFN3x3-10L package.
APPLICATIONS




Cellular Telephones, PDA, MP3 Players
Charging Docks and Cradles
Handheld Battery-Powered Devices
Handheld Computers
TYPICAL APPLICATION
PIN OUT & MARKING
GND
C3
10uF
4.2V
Device parameter should be select as typical application
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DFN3x3-10L
BG: Product Code
LL: LOT NO. H: FAB Code
YW: Date code (Year & Week)
4.35V
10
9
8
FB
CHRIN
GND
7
EN
VIN
BAT
SW
6
10
9
8
7
SW
BG I
LLHYW
ON
FB
Ctrl
5
OFF
CHRG
EN
GND
4
EN
C2
10uF
R1
330
10k
5
R3
R4
ISET
3
FB
ISET
4
C1
10uF
CHRIN
CHRG
2
Ctrl
CHRIN
BAT
1
LC6101
BL8578
110K
75K
ISET
BG
LLHYW
R2
BAT
CHRG
3
Ctrl
To 4.2V
Li-Ion Battery
2
VIN
SW
1
5V USB
Input
1uH
6
L1
VIN
BL8578
ORDERING INFORMATION
PART No.
PACKAGE
Tape&Reel
BL8578CKATR42
BL8578CKATR435
DFN3x3-10L
DFN3x3-10L
3000/Reel
3000/Reel
ABSOLUTE MAXIMUM RATING
Parameter
Value
Max Input Voltage
Max Operating Junction Temperature(Tj)
Ambient Temperature(Ta)
Storage Temperature(Ts)
Lead Temperature & Time
ESD (HBM)
6.5V
125C
-40C – 85C
-55C - 150C
260C, 10S
>2000V
Note: Exceed these limits to damage to the device. Exposure to absolute maximum rating conditions may affect
device reliability.
RECOMMENDED WORK CONDITIONS
Parameter
Value
Input Voltage Range
Operating Junction Temperature(Tj)
Max. 6V
-40C – 85C
ELECTRICAL CHARACTERISTICS
(VDD=5V, TA=25C)
Symbol
Parameter
VIN
ICC
Conditions
Adapter/USB Voltage Range
Input Supply Current
Min
Charge Mode, RISET = 10k, Standby Mode
(Charge Terminated)(Note)
Shutdown Mode (RISET Not Connected)
Regulated Output (Float) Voltage
0°C ≤ TA ≤ 85°C, IBAT = 40mA
RISET = 10k, Current Mode
RISET = 0.66k, Current Mode
Max
Unit
6
V
300
2000
200
500
30
50
4.158
4.2
4.242
4.3065
4.35
4.3935
85
100
115
mA
A
mA
VCC < VBAT, or VCC < VUV)
VFLOAT
Typ
2.6
ITRIKL
Trickle Charge Current
VBAT < VTRIKL, RISET = 2k
20
45
VTRIKL
Trickle Charge Threshold Voltage
RISET = 10k, VBAT Rising
2.8
2.9
3.0
V
VTRHYS
60
85
110
mV
0.93
1
1.07
V
0.315
0.6
V
160
200
mV
BAT Pin Current
1.35
1.5
0
-2.5
1
1
V
1.65
-6
5
5
70
IBAT
Standby Mode, VBAT = 4.2V
Shutdown Mode (RISET Not Connected)
Sleep Mode, VCC = 0V
uA
Trickle Charge Hysteresis Voltage
RISET = 10k
VISET
ISET Pin Voltage
RISET = 10k, Current Mode
VCHRG
CHRG Pin Output Low Voltage
ICHRG = 5mA
Recharge Battery Threshold Voltage
VFLOAT - VRECHRG
ΔVRECHRG
100
uA
Note : Supply current includes ISET pin current (approximately 100μA) but does not include any current delivered to
the battery through the BAT pin (approximately 100mA).
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BL8578
PIN DESCRIPTION
PIN #
NAME
1
CHRG
2
ISET
3
Ctrl
4
EN
5
FB
6
VIN
7
SW
8
9
GND
CHRIN
10
BAT
DESCRIPTION
Open-Drain Charge Status Output. When the battery is charging, the CHRG pin is pulled low
by an internal N-channel MOSFET. When the charge cycle is completed, When the BL8578
detects an under voltage lockout condition, CHRG is forced high impedance.
Charge Current Program, Monitor the charge current and Shutdown. This pin set to 1V in
constant-current mode. The charge current is programmed by connecting a 1% resistor,
RISET, to GND pin.
Sense Feedback Voltage Pin.
Enable Input Pin. Pulling the EN pin high places the BL8578 into a low power state where
the BAT drain current drops to less than 3μA and the supply current is reduced to less than
50μA. For normal operation, pull the pin low.
Battery Feedback Voltage.
Positive Supply Voltage Input. This pin connects to the power devices inside the chip. VIN
ranges from 4V to 5.5V for normal operation. Operation down to the under-voltage lockout
threshold is allowed with current limited wall adapters. Decouple with a 10μF or larger
surface mounted ceramic capacitor.
Switch Node Connection. This pin connects to the drains of the internal main and
synchronous power MOSFET switches. Connect to external inductor.
Ground.
Power Path Output Voltage.
Battery Charger Output Terminal. Connect a 22μF ceramic chip capacitor between BAT and
PGND to keep the ripple voltage small.
BLOCK DIAGRAM
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BL8578
ELECTRICAL PERFORMANCE
Efficiency vs. VBAT
Vbat Vs Ichr
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Efficiency(%)
Ichr(A)
Tested under TA=25C, unless otherwise specified
Vbat Vs Ichr
2.7 3.1 3.3 3.5 3.7 3.9 4.1
100
90
80
70
60
50
40
30
20
10
0
Vin=5V
3.0
Vbat(V)
3.4
ISET Pin Pull-up Current vs.
Temperature and VIN
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
3.5
3.3
IISET（uA)
IBAT（A)
4.2
VBAT(V)
IBAT vs. RISET
3.1
2.9
2.7
Vin=4.25V
Vin=6V
2.5
0.2
0.7
1.2
RISET(Kohm)
1.7
2.2
-50
Regulated Output (Float) Voltage vs.
Temperature
4.30
4.28
4.26
4.24
4.22
4.20
4.18
4.16
4.14
4.12
4.10
0
50
100
Temperatures（℃）
150
CHRG pin Current vs. Temperature
(strong Pull-down State)
20
18
16
ICHRG(mA )
Vfloat(V)
3.8
14
12
10
8
6
Vin=5V, RISET=10k
-50
0
50
100
-50
Temperatures(℃)
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Vin=5V, VBAT=4V, VCHRG=1V
4
4
0
50
Temperatures（℃）
100
BL8578
CHRG Current vs. Temperature
VISET vs. Temperature
600
500
300
VISET(V)
IBAT(mA )
400
RISET=2k
RISET=10k
200
100
0
-50
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0
50
Temperatures（℃）
1.10
1.08
1.06
1.04
1.02
1.00
0.98
0.96
0.94
0.92
0.90
RISET=2k
RISET=10k
-50
100
0
50
Temperatures（℃）
5
100
BL8578
DETAILED DESCRIPTION
General description
The BL8578 is a constant current, constant
voltage Li-Ion battery switching charger controller.
The charge current is set by an external sense
resistor (RISET) across the ISET and GND pins. The
final battery float voltage is internally set to
4.2V/4.35V per cell. For batteries like lithium-ion
that require accurate final float voltage, the
internal reference, voltage amplifier and the
resistor divider provide regulation with ±1%
accuracy.
When the battery voltage approaches the
programmed float voltage, the charge current
will start to decrease. It terminates the charge
cycle when the charge current falls to 10% of the
full-scale value after the final float voltage is
reached. When the ISET pin voltage falls below
100mV for longer than tTERM (typically 1ms),
charging is terminated. The charge current is
latched off and the BL8578 enters standby mode,
where the input supply current drops to 200μA.
(Note: C/10 termination is disabled in trickle
charging and thermal limiting modes).
Manual Shutdown
Floating the ISET pin by removing the resistor from
ISET pin to ground can put the device in shutdown
mode. The battery drain current is thus reduced to
less than 5μA and the supply current to less than
50μA. Reconnecting the resistor back will restart a
new charge cycle.
A charge cycle begins when the voltage at the
VCC pin rises above the UVLO level and is 250mV
or more greater than the battery voltage. At the
beginning of the charge cycle, if the battery
voltage is less than the trickle charge threshold,
2.9V for the 4.2 version, the charger goes into
trickle charge mode. The trickle charge current is
internally set to 10% of the full-scale current. The
charge current is programmable by setting the
value of a precision resistor connected from the
ISET pin to ground. The charge current is 1000
times of the current out of the ISET pin. The
program resistor and the charge current are
calculated using the following equations:
The charge current out of the BAT pin can be
determined at any time by monitoring the ISET pin
voltage using the following equation:
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Once manually shutdown, the CHRG pin is in a weak
pull-down state if VIN is above UVLO voltage. The
CHRG pin is in a high impedance state if the BL8578
is in under voltage lockout mode.
Automatic Recharge
After the termination of the charge cycle, the
BL8578 constantly monitors the BAT pin voltage
and starts a new charge cycle when the battery
voltage falls below 4.05V, keeping the battery at
fully charged condition. CHRG output enters a
strong pull-down state during recharge cycles.
Inductor Selection
The peak-to-peak ripple is limited to 30% of the
maximum output current. This places the peak
current far enough from the minimum over current
trip level to ensure reliable operation while
providing enough current ripples for the current
mode converter to operate stably. In this case, for
1.6A maximum output current, the maximum
inductor ripple current is 667 mA. The inductor size
is estimated as following equation:
BL8578
Layout Considerations
CIN must be close to Pins VIN and GND, the loop
area formed by CIN and GND must be minimized.
Place CCHRIN as close to Pins CHRIN and GND. The
PCB copper area associated with SW pin must be
minimized to avoid the potential noise problem.
FB Resistors and the traces connecting to the FB
pin must not adjacent to the SW net on the PCB
layout to avoid the noise problem. ISET resistor
must be as far away with the SW net as possible.
The thermal pad under the IC must be tied to the
ground area on the top layer, and use via to
connect this ground area to any internal ground
planes.
PACKAGE OUTLINE
Package
DFN3x3-10L
Package specification：
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Devices per reel
7
3000
Unit
mm