®
RT9526A
Linear Single Cell Li-Ion Battery Charger with Input Over
Voltage Protection
General Description
Features
The RT9526A is a fully integrated low cost single cell Liion battery charger ideal for portable applications. The
RT9526A is capable of being powered up from AC adapter
and USB (Universal Serial Bus) port inputs. The RT9526A
enters sleep mode when supplies are removed. The
RT9526A optimizes the charging task by using a control
algorithm including preconditioning mode, fast charge
mode, and constant voltage mode. The charging task will
remain in constant voltage mode to hold the battery in a
full charge condition. The charge current can be
programmed with an external resistor. The internal thermal
feedback circuitry regulates the die temperature to optimize
the charge rate under all ambient temperatures. The
RT9526A features 28V maximum rating voltage for VIN.
Under-voltage protection and over-voltage protection are
provided for the AC adapter supply.
28V Maximum Rating for AC Adapter with OverVoltage Protection 7V
Internal Integrated Power FETs
AC Adapter Power Good Status Indicator
Programmed Charging Current
Charge Status Indicator
Programmed End of Charge Current
Under-Voltage Protection
Thermal Feedback Optimizing Charge Rate
RoHS Compliant and Halogen Free
Ordering Information
RT9526A
Package Type
QW : WDFN-8L 2x3 (W-Type)
E : SOT-23-6
Lead Plating System
G : Green (Halogen Free and Pb Free)
The RT9526A is available in the WDFN-8L 2x3 and
SOT-23-6 package to achieve best solution for PCB space
and total BOM cost saving considerations.
Note :
Richtek products are :
ments of IPC/JEDEC J-STD-020.
Applications
RoHS compliant and compatible with the current require-
Cellular Phones
Digital Cameras
PDAs and Smart Phones
Portable Instruments
Suitable for use in SnPb or Pb-free soldering processes.
Simplified Application Circuit
Adapter or USB
VIN
CIN
RISET
RIMIN
BATT
RT9526A
COUT
ISET
IMIN
GND
R1
PGB
VBATT
R2
CHG_SB
VBATT
ENB
Copyright © 2014 Richtek Technology Corporation. All rights reserved.
DS9526A-03 July 2014
is a registered trademark of Richtek Technology Corporation.
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1
RT9526A
Marking Information
Pin Configurations
RT9526AGQW
(TOP VIEW)
W : Date Code
05W
VIN
PGB
CHG_SB
ENB
RT9526AGE
1
2
3
4
GND
05 : Product Code
9
8
7
6
5
BATT
ISET
IMIN
GND
WDFN-8L 2x3
0X= : Product Code
0X=DNN
DNN : Date Code
IMIN ISET BATT
6
5
4
2
3
CHG_SB GND VIN
SOT-23-6
Function Pin Description
Pin No.
Pin Name
Pin Function
WDFN-8L 2x3
SOT-23-6
1
3
VIN
Supply Voltage Input. VIN can withstand up to 28V input.
2
--
PGB
Power Good Indicator. This pin connects to VIN with 10SL N-MOSFET
as power good condition.
3
1
CHG_SB
Charge Status Indicator Output (Open-Drain). Indicate low when
battery is charging; indicate high when battery charging finished or any
fault happened.
4
--
ENB
Enable Control Input (Active Low). Connect this pin with a 200k
pull-low resistor.
5,
9 (Exposed Pad)
2
GND
Ground. The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
6
6
IMIN
EOC Current Setting.
7
5
ISET
Charge Current Set Point.
8
4
BATT
Battery Charge Current Output.
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is a registered trademark of Richtek Technology Corporation.
DS9526A-03 July 2014
RT9526A
Function Block Diagram
Switch
Well
BATT
VIN
BASE
VREF
IBIAS
Sleep
Mode
ISET
Current
Set Block
CC/CV/TR
Multi Loop
Controller
EOC Set
Block
IMIN
CHG_SB
OVP
UVLO
PGB
Logic
ENB
200k
GND
Operation
The RT9526A is a fully integrated low cost single cell Liion charger. It provides a fast-charge current setting by
resistor RIREF. Pre-charge is 16.7% of fast charge current,
while VBAT < 2.45V. The PGB pin is low, while VIN >
POR, VIN < OVP, and VIN − VBAT > VOSH_H. The CHG_SB
pin is low, while RT9526A is charging. The CHG_SB pin
will go high while end of charger happens. End of charge
condition is set by RIMIN. CHG_SB will go low again, while
charge current is larger than 75% of fast-charge setting.
The RT9526A charges continuously after end of charge
happens. Li-ion battery will be full charged until CV = 4.2V.
The RT9526A can be disabled by ENB = H.
Copyright © 2014 Richtek Technology Corporation. All rights reserved.
DS9526A-03 July 2014
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RT9526A
Absolute Maximum Ratings
(Note 1)
Supply Voltage, VIN -----------------------------------------------------------------------------------------------------CHG_SB, PGB -----------------------------------------------------------------------------------------------------------Other Pins ------------------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C
WDFN-8L 2x3 -------------------------------------------------------------------------------------------------------------SOT-23-6 -------------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2)
WDFN-8L 2x3, θJA --------------------------------------------------------------------------------------------------------WDFN-8L 2x3, θJC --------------------------------------------------------------------------------------------------------SOT-23-6, θJA --------------------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Storage Temperature Range --------------------------------------------------------------------------------------------
Recommended Operating Conditions
−0.3V to 28V
−0.3V to 7V
−0.3V to 6V
3.17W
0.48W
31.5°C/W
7.5°C/W
208.2°C/W
260°C
150°C
−65°C to 150°C
(Note 3)
Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C
Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C
Electrical Characteristics
(VIN = 4.5V, TA = 25°C unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
VIN POR Rising Threshold
Voltage
VPOR_H
3.4
3.8
4.2
V
VIN POR Falling Threshold
Voltage
VPOR_L
3.1
3.5
3.9
V
VIN VBATT VOS Rising
VOS_H
--
90
150
mV
VIN VBATT VOS Falling
VOS_L
10
50
--
mV
--
400
600
A
VIN Standby Current
VBATT = 4.5V
BATT Sleep Leakage Current
ISLEEP
--
1
5
A
Battery Regulation Voltage
VREG
4.158
4.2
4.242
V
VIN Power MOSFET
On-Resistance
RDS(ON)
--
0.6
--
ISET Set Voltage
(Fast Charge Phase)
VISET
--
1.22
--
V
450
500
550
mA
Charge Current Accuracy
I BATT = 0.5A
RISET = 24.3k
BATT Pre-Charge Threshold
VCHG_PRE
2.45
2.55
2.65
V
BATT Pre-Charge Threshold
Hysteresis
VCHG_PRE
40
100
150
mV
Pre-Charge Current
ICHG_PRE
12
16.7
21.3
%
1.5
--
--
--
--
0.4
--
115
--
Logic-High VIH
ENB Input
Threshold Voltage Logic-Low VIL
Thermal Regulation
VIN = 4.2V to 24V
TREG
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V
C
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DS9526A-03 July 2014
RT9526A
Parameter
Symbol
VIN Over-Voltage Protection
Threshold
VOVP
VIN OVP Hysteresis
VOVP
Test Conditions
Min
Typ
Max
Unit
6.7
7
7.5
V
--
0.1
--
V
PGB Pull-Down Voltage
5mA
--
200
--
mV
CHG_SB Pull-Down Voltage
5mA
--
200
--
mV
RIMIN = 243k
--
45
--
mA
RIREF = 24.3k
337.5
375
412.5
mA
EOC Current Setting
EOC Rising Threshold
IIMIN
Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in
the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may
affect device reliability.
Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is
measured at the exposed pad of the package.
Note 3. The device is not guaranteed to function outside its operating conditions.
Copyright © 2014 Richtek Technology Corporation. All rights reserved.
DS9526A-03 July 2014
is a registered trademark of Richtek Technology Corporation.
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RT9526A
Typical Application Circuit
Adapter or USB
VIN
CIN
RISET
RIMIN
BATT
RT9526A
COUT
ISET
IMIN
GND
R1
PGB
VBATT
R2
CHG_SB
VBATT
ENB
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is a registered trademark of Richtek Technology Corporation.
DS9526A-03 July 2014
RT9526A
Typical Operating Characteristics
VOUT Regulation Voltage vs. Input Voltage
BATT Sleep Leakage Current vs. Battery Voltage
BATT Sleep Leakage Current (µA)1
VOUT Regulation Voltage (V)1
4.2420
4.2252
4.2084
4.1916
4.1748
4.1580
4.5
5
5.5
6
6.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
7
1
1.5
Input Voltage (V)
2
2.5
3
3.5
4
4.5
Battery Voltage (V)
Pre-Charge Current vs. Input Voltage
Charge Current vs. Input Voltage
550
95
Pre-Charge Current (mA)
540
Charge Current (mA)
530
520
510
500
490
480
470
460
91
87
83
79
VBATT = 3.8V, RISET = 24.3kΩ
VBATT = 3.8V, RISET = 24.3kΩ
450
75
4
4.5
5
5.5
6
6.5
7
4
4.5
5
5.5
6
Input Voltage (V)
Input Voltage (V)
ISET Voltage vs. Input Voltage
OVP
6.5
7
1.25
ISET Voltage (V)
ENB : Low
VIN
(10V/Div)
1.24
1.23
VBATT
(2V/Div)
1.22
V CHG_SB
(2V/Div)
I CHG
(500mA/Div)
1.21
VBATT = 3.8V, RISET = 24.3kΩ
VIN = 0V to 12V, VBATT = 3.8V, RISET = 24.3kΩ
1.20
4
4.5
5
5.5
6
6.5
7
Time (500μs/Div)
Input Voltage (V)
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DS9526A-03 July 2014
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RT9526A
Shutdown
Power On
ENB : Low
ENB : Low
VIN
(5V/Div)
VIN
(5V/Div)
VBATT
(2V/Div)
V CHG_SB
(2V/Div)
VBATT
(2V/Div)
V CHG_SB
(2V/Div)
I CHG
(500mA/Div)
I CHG
(500mA/Div)
VBATT = 3.8V, RISET = 24.3kΩ
Time (500μs/Div)
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VBATT = 3.8V, RISET = 24.3kΩ
Time (5ms/Div)
is a registered trademark of Richtek Technology Corporation.
DS9526A-03 July 2014
RT9526A
Application Information
The RT9526A is a fully integrated low cost single cell Liion battery charger operable in Constant Current (CC) mode
or Constant Voltage (CV) mode. The CC mode current is
set with the external resistor, RISET, and the CV mode
voltage is fixed at 4.2V. If the battery voltage is below a
typical 2.55V pre-charge threshold, the RT9526A charges
the battery with a trickle current until the battery voltage
rises above the pre-charge threshold. The RT9526A is
capable of being powered up from AC adapter and USB
(Universal Serial Bus) port inputs.
Trickle
CC
CV
4.2V
Charge
Voltage
ICHG_FAST
75 %
ICHG_FAST
Charge
Current
2.8V
IIMIN
16.7 %
ICHG_FAST
CHG_SB
CHG
Indication
Time
Figure 1. Typical Charge Profile
VIN Over-Voltage Protection
a. Battery Pre-Charge Current
The input voltage is monitored by the internal comparator.
The OVP threshold is set at 7V (typ.). When the input
voltage exceeds the threshold, the controller outputs a
logic signal to turn off the power P-MOSFET to prevent
the electronics in the handheld system from damaging
due to high input voltage. Nevertheless, an AC input voltage
over 28V will still damage the RT9526A. When the input
over-voltage condition is removed, the controller will enable
the output again by running through soft-start.
During a charge cycle, if the battery voltage is below the
pre-charge threshold, the RT9526A applies a pre-charge
mode to the battery. This feature revives deeply discharged
cells and protects battery life. The internally determined
pre-charge rate of the RT9526A is 16.7% of the constant
charge current.
Charger Enable Input
ENB is an active-low logic input to enable the charger.
Drive the ENB pin low or leave it floating to enable the
charger. This pin has a 200kΩ internal pull-down resistor.
So when left floating, the input is equivalent to logic-low.
Drive this pin high to disable the charger.
b. Battery Fast-Charge Current (CC Mode)
The RT9526A offers ISET pin to determine the fast-charge
current via an external resistor, RISET, connected between
ISET and GND. The fast-charge current can be calculated
by the following equation :
V
ICHG_FAST = KISET x ISET (mA)
RISET
KSET = 9959; VSET = 1.22 (typ.)
Battery Charge Current vs. RISET
Battery Charge Profile
The RT9526A charges a Li-ion battery under Constant
Current (CC) mode or Constant Voltage (CV) mode. The
constant current of ISET is set via the external resistor,
RISET, and the constant voltage is fixed at 4.2V. If the battery
voltage is below a typical 2.55V pre-charge threshold, the
RT9526A charges the battery with a trickle current until
the battery voltage rises above the pre-charge threshold.
When the battery voltage reaches 4.2V, the charger enters
CV mode and regulates the battery voltage at 4.2V to
fully charge the battery without the risk of over charge.
Battery Charge Current (mA) 1
1400
1200
1000
800
600
400
200
0
10
19
28
37
46
55
RISET (k Ω )
Figure 2
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RT9526A
c. Battery Voltage Regulation (CV Mode)
The battery voltage regulation feedback is through the
BATT pin. The RT9526A monitors the battery voltage
between the BATT and GND pins. When battery voltage is
close to battery regulation voltage threshold, the voltage
regulation phase begins and the charging current begins
to taper down. When battery voltage is over battery
regulation voltage threshold and charge mode stops, the
RT9526A still monitors the battery voltage. Charge current
is resumed when the battery voltage falls under battery
regulation voltage threshold.
Sleep Mode
The RT9526A enters sleep mode if both AC and USB are
removed from the input. This feature prevents draining the
battery during the absence of input supply.
Power Good
This open-drain output pin is used to indicate the input
voltage status. The PGB output asserts low when
1. VIN > VPOR
2. VIN − VBATT > VOS
3. VIN < VOVP
CHG_SB Indication
The CHG_SB pin is an open-drain output capable to at
least 10mA current when the charger starts to charge and
turns off when the EOC current is reached. The CHG_SB
signal is interfaced either with a micro processor GPIO or
an LED for indication.
End-Of-Charge Current (EOC)
Connect a resistor between the IMIN pin and GND to set
the EOC current. The EOC current level, I IMIN, is
programmable via the external resistor, RIMIN (kΩ), as
shown in the following equation :
(mA)
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Temperature Regulation and Thermal Protection
In order to maximize charge rate, the RT9526A features a
junction temperature regulation loop. If the power
dissipation of the IC results in junction temperature greater
than the thermal regulation threshold (115°C), the RT9526A
will cut back on the charge current and disconnect the
battery in order to maintain thermal regulation at around
115°C. This operation continues until the junction
temperature falls below thermal regulation threshold
(115°C) by the hysteresis level. This feature prevents the
maximum power dissipation from exceeding typical design
conditions.
Selecting the Input and Output Capacitors
It can be used to drive an LED or communicate to the
host processor. Note that ON indicates the open-drain
transistor is turned on and LED is bright.
IIMIN = 10935
RIMIN
Upon reaching the End-Of-Charge (EOC) current, the
charger indicates charge completion via the CHG_SB pin,
but the charger continues to output 4.2V voltage. Figure
1 shows the typical charge profile and the EOC/reset
event. The CHG_SB signal asserts low when the trickle
charge starts and changes to high at EOC. After EOC is
reached, the charge current has to rise above 75% of
ICHG_FAST before the CHG_SB signal is allowed to turn on
again. A current surge after EOC may occur due to a load
connected to the battery.
In most applications, a 1μF high frequency decoupling
capacitor placed in close proximity to the input is sufficient.
However, depending on the power supply characteristics
and cable length, it may be necessary to add an additional
10μF ceramic capacitor to the input. For the RT9526A, a
small output capacitor is required for loop stability. A 1μF
ceramic capacitor placed between the BATT pin and GND
is typically sufficient.
Thermal Considerations
For recommended operating condition specifications, the
maximum junction temperature is 125°C. The junction to
ambient thermal resistance, θJA, is layout dependent. For
WDFN-8L 2x3 package, the thermal resistance, θJA, is
31.5°C/W on a standard JEDEC 51-7 four-layer thermal
test board. For SOT-23-6 package, the thermal resistance,
θJA, is 208.2°C/W on a standard JEDEC 51-7 four-layer
thermal test board. The maximum power dissipation at TA
= 25°C can be calculated by the following formula :
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DS9526A-03 July 2014
RT9526A
PD(MAX) = (125°C − 25°C) / (31.5°C/W) = 3.17W for
WDFN-8L 2x3 package
Layout Consideration
The RT9526A is a fully integrated low cost single-cell Liion battery charger ideal for portable applications. Careful
PCB layout is necessary. For best performance, place all
peripheral components as close to the IC as possible. A
short connection is highly recommended. The following
guidelines should be strictly followed when designing a
PCB layout for the RT9526A.
PD(MAX) = (125°C − 25°C) / (208.2°C/W) = 0.48W for
SOT-23-6 package
The maximum power dissipation depends on the operating
ambient temperature for fixed T J(MAX) and thermal
resistance, θJA. The derating curve in Figure 3 allow the
designer to see the effect of rising ambient temperature
on the maximum power dissipation.
Input capacitor should be placed close to the IC and
connected to the ground plane. The trace of input on
the PCB should be placed far away from the sensitive
devices and shielded by the ground.
The GND and exposed pad should be connected to a
strong ground plane for heat sinking and noise protection.
The connection of RISET should be isolated from other
noisy traces.
Output capacitor should be placed close to the IC and
connected to the ground plane to reduce noise coupling.
Maximum Power Dissipation (W)1
4.0
Four-Layer PCB
3.5
WDFN-8L 2x3
3.0
2.5
2.0
1.5
1.0
SOT-23-6
0.5
0.0
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 3. Derating Curve of Maximum Power Dissipation
CIN should be placed near the
IC to improve performance.
VIN
BATT
R1
BATT
BATT
R2
VIN
PGB
CHG_SB
ENB
1
2
3
4
COUT
GND
CIN
The copper area connecting the
resistors of ISET and IMIN should
be minimized and kept far away
from noise sources.
9
8
7
6
5
BATT RISET
ISET
IMIN
GND RIMIN
GND
The GND plane should be connected to a strong
ground plane for heat sinking and noise protection.
Figure 4. PCB Layout Guide
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RT9526A
Outline Dimension
D
D2
L
E
E2
SEE DETAIL A
1
e
b
2
A
A1
1
2
1
A3
DETAIL A
Pin #1 ID and Tie Bar Mark Options
Note : The configuration of the Pin #1 identifier is optional,
but must be located within the zone indicated.
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min
Max
Min
Max
A
0.700
0.800
0.028
0.031
A1
0.000
0.050
0.000
0.002
A3
0.175
0.250
0.007
0.010
b
0.200
0.300
0.008
0.012
D
1.900
2.100
0.075
0.083
D2
1.550
1.650
0.061
0.065
E
2.900
3.100
0.114
0.122
E2
1.650
1.750
0.065
0.069
e
L
0.500
0.350
0.020
0.450
0.014
0.018
W-Type 8L DFN 2x3 Package
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DS9526A-03 July 2014
RT9526A
H
D
L
C
B
b
A
A1
e
Symbol
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
0.889
1.295
0.031
0.051
A1
0.000
0.152
0.000
0.006
B
1.397
1.803
0.055
0.071
b
0.250
0.560
0.010
0.022
C
2.591
2.997
0.102
0.118
D
2.692
3.099
0.106
0.122
e
0.838
1.041
0.033
0.041
H
0.080
0.254
0.003
0.010
L
0.300
0.610
0.012
0.024
SOT-23-6 Surface Mount Package
Richtek Technology Corporation
14F, No. 8, Tai Yuen 1st Street, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5526789
Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should
obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot
assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be
accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third
parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries.
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