Datasheet RT9526AGE, RT9526AGQW Datasheet (Richtek) [ru]

®
RT9526A
Linear Single Cell Li-Ion Battery Charger with Input Over Voltage Protection
The RT9526A is a fully integrated low cost single cell Li­ion battery charger ideal for portable applications. The RT9526A is capa ble of being powered up from AC ada pter and USB (U niversal Serial Bus) port inputs. The RT9526A enters sleep mode when supplies are removed. The RT9526A opti mizes the charging task by using a control algorithm including preconditioning mode, fast charge mode, and consta nt voltage mode. The charging ta sk will remain in constant voltage mode to hold the battery in a full charge condition. The charge current can be programmed with a n external resistor . The internal thermal feedback circuitry regulates the die temperature to opti mize the charge rate under all ambient temperatures. The RT9526A features 28V maximum rating voltage for VIN. Under-voltage protection a nd over-voltage protection are provided for the AC a da pter supply.
The RT9526A is available in the WDFN-8L 2x3 and SOT-23-6 pa ckage to achieve be st solution for PCB space and total BOM cost saving considerations.
Applications
Cellular PhonesDigital Camera sPDAs and Smart PhonesPortable Instruments
Features

28V Maximum Rating for AC Adapter with Over-

Voltage 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)
Note : Richtek products are :
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
Simplified Application Circuit
Adapter or USB
C
IN
R
ISET
R
IMIN
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VIN
ISET IMIN
GND
ENB
RT9526A
CHG_SB
BATT
PGB
R1
R2
C
OUT
V
BATT
V
BATT
1
RT9526A
Marking Information
RT9526AGQW
05 : Product Code
05W
RT9526AGE
0X=DNN
W : Date Code
0X= : Product Code DNN : Date Code
Function Pin Description
Pin No.
WDFN-8L 2x3 SO T-2 3- 6
1 3 VIN Supply Voltage Input. VIN can withstand up to 28V input. 2 -- PGB
3 1 CHG_SB
4 -- ENB
5,
9 (Exp ose d Pad)
2 GND
6 6 IMIN EOC Current Setting. 7 5 ISET Charge Current Set Point. 8 4 BATT Battery Charge Current Output.
Pin Name Pin Fun ction
Pin Configurations
(TOP VIEW)
1
VIN
2
PGB
CHG_SB
3 4
ENB
WDFN-8L 2x3
IMIN
CHG_SB
SOT-23-6
Po wer Go od In dic ato r . This pin con nec ts to VIN with 10S L N-M O SFE T as power good condition.
Charge Status Indicator Output (Open-Drain). Indicate low when bat t ery is charging; indi c ate hi gh wh en ba tte r y char gi ng fi nish ed or an y fault happened.
Enable Control Input (Active Low). Connect this pin with a 200k pull-low resistor.
Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation.
8 7 6
GND
9
5
ISET BATT
4
56
23
VIN
GND
BATT ISET IMIN GND
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Function Block Diagram
RT9526A
Switch
Well
Operation
VIN
ISET
ENB
BASE
Sleep Mode
Current
Set Block
OVP
UVLO
200k
V I
BIAS
REF
CC/CV/TR Multi Loop
Controller
Logic
EOC Set
Block
BATT
IMIN
CHG_SB
PGB
GND
The RT9526A is a fully integrated low cost single cell Li­ion charger. It provides a fast-charge current setting by resistor R
. Pre-charge is 16.7% of fast charge current,
IREF
while VBAT < 2.45V. The PGB pin is low, while VIN > POR, VIN < OVP , and VIN VBA T > V
. The CHG_SB
OSH_H
pin is low, while RT9526A is charging. The CHG_SB pin will go high while end of charger happen s. End of charge condition is set by R
. CHG_SB will go low again, while
IMIN
charge current is larger than 75% of fast-charge setting. The RT9526A charges continuously after end of charge happen s. Li-ion battery will be full charged until CV = 4.2V . The RT9526A ca n be disa bled by ENB = H.
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RT9526A
Absolute Maximum Ratings (Note 1)
Supply V oltage, VIN ------------------------------------------------------------------------------------------------------ 0.3V to 28VCHG_SB, PGB ------------------------------------------------------------------------------------------------------------ 0.3V to 7VOther Pins------------------------------------------------------------------------------------------------------------------- 0.3V to 6VPower Dissipation, P
WDFN-8L 2x3 -------------------------------------------------------------------------------------------------------------- 3.17W SOT-23-6 -------------------------------------------------------------------------------------------------------------------- 0.48W
Package Thermal Re sistance (Note 2)
W DF N-8L 2x3, θJA--------------------------------------------------------------------------------------------------------- 31.5°C/W WDFN-8L 2x3, θJC--------------------------------------------------------------------------------------------------------- 7.5°C/W SOT-23-6, θJA--------------------------------------------------------------------------------------------------------------- 208.2°C/W
Lead Temperature (Soldering, 10 sec.)------------------------------------------------------------------------------- 260°CJunction T emperature----------------------------------------------------------------------------------------------------- 150°CStorage T emperature Range -------------------------------------------------------------------------------------------- 65°C to 150°C
Recommended Operating Conditions (Note 3)
Junction T emperature Range-------------------------------------------------------------------------------------------- 40°C to 125°CAmbient T emperature Range-------------------------------------------------------------------------------------------- 40°C to 85°C
@ T
D
= 25°C
A
Electrical Characteristics
(V
= 4.5V, T
IN
VI N POR Ri si ng Thresh old
Voltage
VIN POR Falling Threshold
Voltage
VIN V VIN V VI N Standby Cur rent V BATT Sleep Leakage Current I Battery Regulation Voltage V VIN Power M OSFET
On-Resistance
IS ET Set Volta ge
(Fast Charge Phase)
Cha r ge Cur ren t Acc urac y R BATT Pre- Cha r ge Thr es hol d V BATT Pre- Cha r ge Thr es hol d
Hysteresis
Pre-Charge Current I ENB Input
T hres hol d Vol tag e
Th erm al R egu lati on T
= 25°C unless otherwise specified)
A
Parameter Symbol Test Conditions Min Typ Max Unit
VOS Rising V
BATT
VOS Fa llin g V
BATT
Logic-High V
V
V
SLEEP
R
V
V
CHG_PRE
3.4 3.8 4.2 V
POR_H
3.1 3.5 3.9 V
POR_L
-- 90 150 mV
OS_H
10 50 -- mV
OS_L
-- 1 5 A
4.158 4.2 4.242 V
REG
I
DS(ON)
-- 1.22 -- V
ISET
CHG_PRE
CHG_PRE
2.45 2.55 2.65 V 40 100 150 mV
12 16.7 21.3 %
IH
Logic-Low VIL -- -- 0.4
-- 115 -- C
REG
= 4.5V -- 400 600 A
BATT
= 0.5A -- 0.6 --
BATT
= 24.3k 450 500 550 mA
ISET
= 4.2V to 24V
V
IN
1.5 -- -­V
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RT9526A
Parameter Symbol Test Conditions Min Typ Max Unit
VIN Over-Voltage Protection Threshold
VIN OVP Hysteresis V PGB Pull-Down Voltage 5mA -- 200 -- mV CHG_SB Pull-Down Voltage 5mA -- 200 -- mV EOC Current Setting I EOC Rising Threshold R
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. θ
Note 3. The device is not guaranteed to function outside its operating conditions.
is measured at T
JA
measured at the exposed pad of the package.
A
V
6.7 7 7.5 V
OVP
-- 0.1 -- V
OVP
R
IMIN
= 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is
= 243k -- 45 -- mA
IMIN
= 24.3k 337.5 375 412.5 mA
IREF
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5
RT9526A
Typical Application Circuit
Adapter or USB
R R
C
IN
ISET
IMIN
VIN
ISET IMIN
GND
ENB
RT9526A
CHG_SB
BATT
PGB
R1
R2
C
OUT
V
BATT
V
BATT
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Typical Operating Characteristics
)
)
RT9526A
VOUT Regulation Voltage vs . Input Voltage
4.2420
4.2252
4.2084
4.1916
4.1748
VOUT Regul ation Voltage (V) 1
4.1580
4.5 5 5.5 6 6.5 7
Inp ut Voltage (V)
Charge Current vs. Input Voltage
550 540 530 520 510 500 490 480 470
Charge Current (m A
460 450
4 4.5 5 5.5 6 6.5 7
V
= 3.8V, R
BATT
Input Voltage (V)
= 24.3kΩ
ISET
BATT Sleep Leakage Current vs. Battery Voltage
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
BATT Sleep Leakage Current (µ A) 1
0.0 1 1.5 2 2.5 3 3.5 4 4.5
Bat tery Volt age (V)
Pre-Charge Current vs. Input Voltage
95
91
87
83
79
Pre- C harge Current (mA
V
= 3.8V, R
75
44.555.566.57
BATT
Input Voltage (V)
= 24.3kΩ
ISET
1.25
1.24
1.23
ISET Voltage vs. Input Voltage
V
IN
(10V/Div)
V
BATT
OVP
ENB : Low
(2V/Div)
1.22
V
ISET Voltage (V)
1.21
V
= 3.8V, R
1.20 4 4.5 5 5.5 6 6.5 7
BATT
= 24.3kΩ
ISET
CHG_SB
(2V/Div)
I
CHG
(500mA/Div)
VIN = 0V to 12V, V
Time (500μs/Div)
BATT
= 3.8V, R
= 24.3kΩ
ISET
Input Voltage (V)
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RT9526A
V
IN
(5V/Div)
V
BATT
(2V/Div)
V
CHG_SB
(2V/Div)
I
CHG
(500mA/Div)
Power On
V
= 3.8V , R
BATT
Time (500μs/Div)
ENB : Low
= 24.3kΩ
ISET
V
IN
(5V/Div)
V
BATT
(2V/Div)
V
CHG_SB
(2V/Div)
I
CHG
(500mA/Div)
Shutdown
V
= 3.8V, R
BATT
Time (5ms/Div)
ENB : Low
= 24.3kΩ
ISET
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Application Information
RT9526A
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, R
, and the CV mode
ISET
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 cap able of being powered up from AC adapter and USB (Universal Seri al Bus) port inputs.
VIN Over-Voltage Protection
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. Neverthele ss, an AC in put voltage over 28V will still da mage the RT9526A. When the input over-voltage condition is removed, the controller will enable the output again by running through soft-start.
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.
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, R
, and the consta nt voltage is fixed at 4.2V . If the battery
ISET
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.
CVCCTrickle
4.2V
I
CHG_FAST
2.8V
16.7 %
I
CHG_FAST
CHG_SB
Charge Current
I
IMIN
CHG
Indication
Charge
Voltage
Figure 1. T ypical Charge Profile
a. Battery Pre-Charge Current
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 con stant charge current.
b. Battery Fast-Charge Current (CC Mode)
The RT9526A of fers ISET pin to determine the fast-charge current via an external re sistor, R
, connected between
ISET
ISET and GND. The fa st-charge current can be calculated by the following equation :
V
I = K x (mA)
CHG_FAST ISET
K
= 9959; V
SET
SET
Battery Cha rge Current vs. R
1400
1200
1000
800
600
400
200
Battery Charge Current (mA) 1
0
10 19 28 37 46 55
ISET
R
ISET
= 1.22 (typ.)
R
ISET
Ω
(k )
ISET
Figure 2
75 % I
CHG_FAST
Time
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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 BA TT and GND pins. When battery voltage is close to battery regulation voltage threshold, the voltage regulation phase begin s 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 a nd 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 a sserts low when
1. VIN > V
2. VIN
−−
V
−−
POR
BATT
> V
OS
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 cha nges to high at EOC. After EOC is reached, the charge current has to rise above 75% of I
CHG_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.
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 (1 15°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.
3. VIN < V
OVP
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 a nd LED is bright.
CHG_SB Indication
The CHG_SB pin is an open-drain output capable to at lea st 10mA current when the charger starts to charge a nd turns off when the EOC current is rea ched. 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 a nd GND to set the EOC current. The EOC current level, I programmable via the external resistor, R
IMIN
, is
IMIN
(kΩ), as
shown in the following equation :
I =
IMIN
10935
R
IMIN
(mA)
Selecting the Input and Output Capacitors
In most applications, a 1μF high frequency decoupling cap acitor pla ced in close proximity to the input is sufficient. However, depending on the power supply chara cteristics and cable length, it may be nec essary to add an addition al 10μF ceramic capacitor to the input. For the RT9526A, a small output cap acitor is required f or loop stability . A 1μF ceramic ca pa citor placed between the BA TT 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 re sistance, 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 pa ckage, the thermal resistance,
θ
, is 208.2°C/W on a standard JEDEC 51-7 four-layer
JA
thermal test board. The maximum power dissipation at T = 25°C can be calculated by the following f ormula :
A
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RT9526A
P
= (125°C − 25°C) / (31.5°C/W) = 3.17W for
D(MAX)
W DF N-8L 2x3 pa ckage P
= (125°C − 25°C) / (208.2°C/W) = 0.48W for
D(MAX)
SOT-23-6 pa ckage The maximum power dissipation depends on the operating
ambient temperature for fixed T
and thermal
J(MAX)
resistance, θJA. The derating curve in Figure 3 allow the designer to see the effect of rising ambient temperature on the maximum power dissipation.
4.0
3.5
WDFN-8L 2x3
3.0
2.5
2.0
1.5
1.0
SOT-23-6
0.5
Maximum Power Dissipation (W) 1
0.0 0 25 50 75 100 125
Ambient Tempera ture ( °C )
Four-Layer PCB
Layout Consideration
The RT9526A is a fully integrated low cost single-cell Li­ion battery charger ideal for portable a pplications. Careful PCB layout is necessary . For best performance, pla ce 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.
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 a nd noise protection.
The connection of R
should be isolated from other
ISET
noisy traces.
Output capacitor should be placed close to the IC and
connected to the ground plane to reduce noise coupling.
Figure 3. Derating Curve of Maxi mum Power Dissi pation
C
should be placed near the
IN
IC to improve performance.
VIN BATT
C
BATT BATT
R1
CHG_SB
R2
VIN
PGB ENB
1 2 3 4
Figure 4. PCB Layout Guide
The copper area connecting the resistors of ISET and IMIN should be minimized and kept far away
C
OUT
IN
8
BATT
7
ISET
6
GND9IMIN
5
GND
The GND plane should be connected to a strong ground plane for heat sinking and noise protection.
from noise sources.
R
ISET
R
IMIN
GND
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RT9526A
Outline Dimension
D
E
A
E2
A3
A1
D2
L
SEE DETAIL A
1
e
b
2
1
1
2
DETAIL A
Pin #1 ID a nd T ie Bar Mark Option s
Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated.
Dimensions In Millimeters Dimensions In Inc hes
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 0.500 0.020 L 0.350 0.450
W-Type 8L DFN 2x3 Package
0.014 0.018
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RT9526A
H
D
L
C
b
A
e
B
A1
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
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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