RICHTEK RT9526

RT9526
Linear Single Cell Li-Ion Battery Charger with Input Over
Voltage Protection
General Description
Features
The RT9526 is a fully integrated low cost single cell Li-ion
battery charger ideal for portable applications. The RT9526
is capable of being powered up from AC adapter and USB
(Universal Serial Bus) port inputs. The RT9526 enters
sleep mode when supplies are removed. The RT9526
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 RT9526 features 28V
maximum rating voltage for VIN. The other features are
under voltage protection and over voltage protection for
the AC adapter supply.
z
and SOT-23-6 packages to achieve best solution for PCB
space and total BOM cost saving considerations.
Ordering Information
z
z
z
z
z
z
z
z
Applications
z
z
z
z
Cellular Phones
Digital Cameras
PDAs and Smart Phones
Portable Instruments
Pin Configurations
(TOP VIEW)
IMIN ISET BATT
RT9526
6
Package Type
E : SOT-23-6
QW : WDFN-8L 2x2 (W-Type)
QWA : WDFN-8L 2x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
2
3
CHG_SB GND VIN
SOT-23-6
VIN
PGB
CHG_SB
ENB
1
2
3
4
9
8
7
6
5
BATT
ISET
IMIN
GND
RoHS compliant and compatible with the current requireWDFN-8L 2x2
ments of IPC/JEDEC J-STD-020.
`
4
Suitable for use in SnPb or Pb-free soldering processes.
VIN
PGB
CHG_SB
ENB
1
2
3
4
GND
`
5
GND
The RT9526 is available in WDFN-8L 2x2, WDFN-8L 2x3
z
28V Maximum Rating for AC Adapter
Internal Integrated Power FETs
AC Adapter Power Good Status Indicator
Programmed Charging Current
Charge Status Indicator
Programmed End of Charge Current
Under Voltage Protection
Over Voltage Protection
Thermal Feedback Optimizing Charge Rate
RoHS Compliant and Halogen Free
9
8
7
6
5
BATT
ISET
IMIN
GND
WDFN-8L 2x3
DS9526-01 April 2011
www.richtek.com
1
RT9526
Marking Information
RT9526GE
RT9526GQW
EN= : Product Code
EX=DNN
RT9526GQWA
JJ : Product Code
DNN : Date Code
04 : Product Code
W : Date Code
JJW
04W
W : Date Code
Typical Application Circuit
Adapter or USB
VIN
CIN
RISET
RIMIN
BATT
COUT
RT9526
ISET
PGB
IMIN
GND
CHG_SB
R1
VBATT
R2
VBATT
ENB
Function Pin Description
SOT-26-6
3
Pin No.
WDFN-8L 2x2 /
WDFN-8L 2x3
1
Pin Name
VIN
Pin Function
6
5
5,
9 (Exposed Pad)
6
7
IMIN
ISET
Supply Voltage Input. VIN can withstand up to 28V input.
Power Good Indicator. This pin connects to VIN with 10SL
N-MOSFET as power good condition.
Charge Status Indicator Output (Open drain). Indicate low when
battery is charging; indicate high when battery charging finished or
any fault happened.
Charge Enable (Active Low). Connect this pin with 200kΩ pull low
resistor.
Ground. The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
EOC Current Setting Pin.
Charge Current Set Point.
4
8
BATT
Battery Charge Current Output.
--
2
PGB
1
3
CHG_SB
--
4
ENB
2
www.richtek.com
2
GND
DS9526-01 April 2011
RT9526
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
ENB
200k
DS9526-01 April 2011
Logic
PGB
GND
www.richtek.com
3
RT9526
Flow Chart
Standby State
P-MOSFET = OFF
VIN - VBATT > VOS
YES
NO
YES
BATT > 2.8V
NO
Soft-Start
NO
Sleep State
P-MOSFET = OFF
VIN < UVLO &
VIN < OVP &
ENB = L
YES
ICHG_FAST, HG_SB = L
CV State
VBATT = 4.2V
ICHG = 0A CHG_SB
=H
Power Off State
P-MOSFET = OFF
Fast-Charge
ICHG_FAST = 150mA
RSET = 29.4k
CHG_SB = L
Pre_Charge
ICHG_PRE = (1/6) x
YES
VBATT ≥
8 4.2V
NO
Any State or
VIN > OVP or
VIN > UVLO or
ENB = H
Figure 1. Operation State Diagram for Charger function
VIN > UVLO
& VIN < OVP &
VIN-VBATT > VOS
YES
NO
PGB = L
PGB = H
Figure 2. PGB State
ENB = L
NO
CHG _SB = H
NO
YES
ICHG < IIMIN &
VBATT > 2.8V
YES
NO
CHG_SB = H
CHG_SB = L
ICHG < ICHG_FAST
& VBATT < 2.8V
YES
Figure 3. CHG_SB State
www.richtek.com
4
DS9526-01 April 2011
RT9526
Absolute Maximum Ratings
z
z
z
z
z
z
z
z
(Note 1)
Supply Voltage, VIN -----------------------------------------------------------------------------------------------------CHG_SB, PGB Pins -----------------------------------------------------------------------------------------------------Others -----------------------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C
SOT-23-6 -------------------------------------------------------------------------------------------------------------------WDFN-8L 2x2 -------------------------------------------------------------------------------------------------------------WDFN-8L 2x3 -------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2)
SOT-23-6, θJA --------------------------------------------------------------------------------------------------------------WDFN-8L 2x2, θJA --------------------------------------------------------------------------------------------------------WDFN-8L 2x2, θJC --------------------------------------------------------------------------------------------------------WDFN-8L 2x3, θJA --------------------------------------------------------------------------------------------------------WDFN-8L 2x3, θJC --------------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Storage Temperature Range --------------------------------------------------------------------------------------------
Recommended Operating Conditions
z
z
−0.3V to 28V
−0.3V to 7V
−0.3V to 6V
0.4W
0.606W
0.833W
250°C/W
165°C/W
8.2°C/W
120°C/W
8.2°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
Min
Typ
Max
Unit
VPOR_H
3.4
3.8
4.2
V
VPOR_H
3.1
3.5
3.9
V
VIN − V BATT VOS Rising
VOS_H
--
90
150
mV
VIN − V BATT VOS Falling
VPOR_L
10
50
--
mV
--
300
500
μA
VIN POR Rising Threshold
Voltage
VIN POR Falling Threshold
Voltage
Symbol
VIN Standby Current
Test Conditions
VBATT = 4.5V
BATT Sleep Leakage Current
ISLEEP
--
1
5
μA
Battery Regulation Voltage
VREG
4.158
4.2
4.242
V
VIN Power FET On-Resistance
ISET Set Voltage (Fast Charge
Phase)
Charge Current Accuracy
RDS(ON)
--
0.6
--
Ω
--
1.21
--
V
135
150
165
mA
BATT Pre-Charge Threshold
V CHG_PRE
2.7
2.8
2.9
V
BATT Pre-Charge Threshold
Hysteresis
ΔVCHG_PRE
40
100
150
mV
Pre-Charge Current
ICHG_PRE
12
16.7
21.3
%
ENB Input
Threshold Voltage
IBATT = 0.5A
VISET
RISET = 29.4kΩ
Logic-High VIH
Logic-Low VIL
VIN = 4.2V to 24V
1.5
--
--
--
--
0.4
V
To be continued
DS9526-01 April 2011
www.richtek.com
5
RT9526
Parameter
Thermal Regulation
VIN Over Voltage Protection
Threshold
VIN OVP Hysteresis
Symbol
Test Conditions
Min
Typ
Max
Unit
TREG
--
115
--
°C
VOVP
10
11
13
V
ΔVOVP
--
0.4
--
V
PGB Pull Down Voltage
5mA
--
200
--
mV
CHG_SB Pull Down Voltage
5mA
--
200
--
mV
RIMIN = 137kΩ
20
30
40
mA
RIREF = 29.4kΩ
90
110
130
mA
EOC Current Setting
IIMIN
EOC Rising Threshold
Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for
stress ratings. 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 for extended periods may
remain possibility to affect device reliability.
Note 2. θJA is measured in natural convection at TA = 25°C on a low-effective thermal conductivity single-layer test board of
JEDEC 51-3
thermal measurement standard. The measurement case position of θJC is on the exposed pad of the
packages.
Note 3. The device is not guaranteed to function outside its operating conditions.
www.richtek.com
6
DS9526-01 April 2011
RT9526
Typical Operating Characteristics
Battery Current vs. Charging Time
Battery Current vs. Charging Time
0.20
4.5
VIN = 5V, RISET = 29.4kΩ,
RIMIN = 137kΩ
0.18
4.0
Battery Voltage (V)
Battery Current (A)
0.16
0.14
0.12
0.10
0.08
0.06
3.5
3.0
2.5
2.0
1.5
0.04
1.0
0.02
0.5
VIN = 5V, RISET = 29.4kΩ,
RIMIN = 137kΩ
0.0
0.00
0
5000
0
10000 15000 20000 25000 30000 35000
5000
10000 15000 20000 25000 30000 35000
Charging Time (s)
Charging Time (s)
Charging Current vs. Input Voltage
4.30
155
4.28
150
Charging Current (mA)1
Battery Regulation Voltage (V)1
Battery Regulation Voltage vs. Charge Current
4.26
4.24
4.22
4.20
4.18
4.16
4.14
4.12
100
200
300
400
140
135
130
125
120
115
110
105
VIN = 5V
RISET = 24.9Ω
100
4.10
0
VBATT = 3V
VBATT = 3.7V
145
3.0
500
4.5
6.0
Charge Current vs. Battery Voltage
Charge Current (mA)
450
9.0
10.5
Battery Regulation Voltage vs. Input Voltage
4.4
VIN = 5V
Battery Regulation Voltage (V)1
500
7.5
Input Voltage (V)
Change Current (mA)
400
350
300
RISET = 9.1k
RISET = 29.4k
RISET = 9.1k
250
200
150
100
50
0
4.2
4.0
3.8
3.6
3.4
IBATT = 20mA
3.2
0.5
1.3
2.1
2.9
Battery Voltage (V)
DS9526-01 April 2011
3.7
4.5
4
5
6
7
8
9
10
11
Input Voltage (V)
www.richtek.com
7
RT9526
Charge Current vs. RISET
Charge Current vs. Temperature
1200
180
1100
Charging Current (mA)1
Charge Current (mA)
160
140
120
100
80
60
40
20
VIN = 5V, VBATT = 3.7V,
RISET = 29.4kΩ
1000
900
800
700
600
500
400
300
200
VIN = 5V, VBATT = 3.7V
100
0
0
-50
-25
0
25
50
75
100
125
Temperature (°C)
3
13
23
33
43
53
63
RISET (kkΩ
Ω)
EOC Current vs. RISET
90
EOC Current (mA)
80
70
60
50
40
30
20
10
VIN = 5V, VBATT = 3.7V
0
50
130
210
290
370
450
( kΩ )
RIMIN (kΩ)
www.richtek.com
8
DS9526-01 April 2011
RT9526
Application Information
The RT9526 is a fully integrated low cost single cell Li-ion
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 2.8V pre-charge threshold, the RT9526 charges
the battery with a trickle current until the battery voltage
rises above the pre-charge threshold. The RT9526 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
Figure 1. Typical Charge Profile
Time
VIN Over Voltage Protection
a. Battery Pre-Charge Current
The input voltage is monitored by the internal comparator.
The OVP threshold is set at 11V (typ.). When the input
voltage exceeds the threshold, the controller outputs a
logic signal to turn off the power P-MOSFET to prevent
high input voltage from damaging the electronics in the
handheld system. Nevertheless, an AC input voltage over
28V will still damage the RT9526. 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 RT9526 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 RT9526 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 RT9526 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 = 3640; VSET = 1.21 (typ.)
c. Battery Voltage Regulation (CV Mode)
Battery Charge Profile
The RT9526 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 2.8V pre-charge threshold, the
RT9526 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.
The battery voltage regulation feedback is through the
BATT pin. The RT9526 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
RT9526 still monitors the battery voltage. Charge current
is resumed when the battery voltage falls under battery
regulation voltage threshold.
Sleep Mode
The RT9526 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.
DS9526-01 April 2011
www.richtek.com
9
RT9526
Power Good
This open-drain output pin is used to indicate the input
voltage status. The PGB output asserts low when
1. VIN > VPOR
temperature falls below thermal regulation threshold
(115°C) by the hysteresis level. This feature prevents the
maximum power dissipation from exceeding typical design
conditions.
2. VIN − VBATT > VOS
Selecting the Input and Output Capacitors
3. VIN < VOVP
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 RT9526, a
small output capacitor is required for loop stability. A 1μF
ceramic capacitor placed between the BATT pin and GND
is typically sufficient.
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.
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, as shown
in the following equation :
IIMIN = 4148
RIMIN
(mA)
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
Thermal Considerations
For recommended operating condition specifications of
the RT9526, the maximum junction temperature is 125°C
and TA is the ambient temperature. The junction to ambient
thermal resistance, θ JA , is layout dependent. For
SOT-23-6 packages, the thermal resistance, θJA, is
250°C/W on a standard JEDEC 51-3 single-layer thermal
test board. For WDFN-8L 2x2 packages, the thermal
resistance, θJA, is 165°C/W on a standard JEDEC 51-3
single-layer thermal test board. For WDFN-8L 2x3
packages, the thermal resistance, θJA, is 120°C/W on a
standard JEDEC 51-3 single-layer thermal test board. The
maximum power dissipation at TA = 25°C can be calculated
by the following formula :
PD(MAX) = (125°C − 25°C) / (250°C/W) = 0.400W for
SOT-23-6 package
PD(MAX) = (125°C − 25°C) / (165°C/W) = 0.606W for
WDFN-8L 2x2 package
again. A current surge after EOC may occur due to a load
connected to the battery.
PD(MAX) = (125°C − 25°C) / (120°C/W) = 0.833W for
WDFN-8L 2x3 package
Temperature Regulation and Thermal Protection
The maximum power dissipation depends on the operating
ambient temperature for fixed T J (MAX) and thermal
resistance, θJA. For the RT9526 packages, the derating
curves in Figure 2 allow the designer to see the effect of
rising ambient temperature on the maximum power
dissipation.
In order to maximize charge rate, the RT9526 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 RT9526
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
www.richtek.com
10
DS9526-01 April 2011
Maximum Power Dissipation (W)1
RT9526
0.9
Layout Consideration
Single-Layer PCB
The RT9526 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 RT9526.
0.8
0.7
0.6
0.5
0.4
WDFN-8L 2x3
WDFN-8L 2x2
SOT-23-6
0.3
0.2
`
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.
0.1
0.0
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 2. Derating Curve for RT9526 Package
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
GND
CIN
COUT
9
8
7
6
5
The copper area connecting the
resistors of ISET and IMIN should
be minimized and kept far away
from noise sources.
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 3. PCB Layout Guide
DS9526-01 April 2011
www.richtek.com
11
RT9526
Outline Dimension
H
D
L
C
B
b
A
A1
e
Dimensions In Millimeters
Dimensions In Inches
Symbol
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
www.richtek.com
12
DS9526-01 April 2011
RT9526
D2
D
L
E
E2
1
e
SEE DETAIL A
b
2
1
2
1
A
A1
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
1.950
2.050
0.077
0.081
D2
1.000
1.250
0.039
0.049
E
1.950
2.050
0.077
0.081
E2
0.400
0.650
0.016
0.026
e
L
0.500
0.300
0.020
0.400
0.012
0.016
W-Type 8L DFN 2x2 Package
DS9526-01 April 2011
www.richtek.com
13
RT9526
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
Richtek Technology Corporation
Richtek Technology Corporation
Headquarter
Taipei Office (Marketing)
5F, No. 20, Taiyuen Street, Chupei City
5F, No. 95, Minchiuan Road, Hsintien City
Hsinchu, Taiwan, R.O.C.
Taipei County, Taiwan, R.O.C.
Tel: (8863)5526789 Fax: (8863)5526611
Tel: (8862)86672399 Fax: (8862)86672377
Email: [email protected]
Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design,
specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed
by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek.
www.richtek.com
14
DS9526-01 April 2011