RICHTEK RT9525

RT9525
Linear Single Cell Li-Ion Battery Charger with Auto Power Path
General Description
Features
The RT9525 is an integrated single cell Li-ion battery
charger with Auto Power Path Management (APPM). No
external MOSFETs are required. The RT9525 enters sleep
mode when power is removed. Charging tasks are
optimized by using a control algorithm to vary the charge
rate including pre-charge mode, fast charge mode and
constant voltage mode. For the RT9525, the charge current
can also be programmed with an external resister.
Additionally, the internal thermal feedback circuitry
regulates the die temperature to optimize the charge rate
for all ambient temperatures. The charging task will always
be terminated in constant voltage mode when the charging
current reduces to the termination current of 20%
ICHG_FAST. Other features include under voltage protection
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28V Maximum Rating for VIN Power
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Selectable Power Current Limit (0.1A / 0.5A / 1.5A)
Integrated Power MOSFETs
Auto Power Path Management (APPM)
Programmable Charging Current Timer and Safe
Charge Timer
Under Voltage Protection
Over Voltage Protection
Power Good and Charger Status Indicator
Optimized Charge Rate via Thermal Feedback
16-Lead WQFN Package
RoHS Compliant and Halogen Free
and over voltage protection for the VIN supply.
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Applications
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Ordering Information
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Digital Cameras
PDAs and Smart Phones
Portable Instruments
RT9525
Pin Configurations
(TOP VIEW)
ISETA
SYSOFF
TIMER
VIN
Package Type
QW : WQFN-16L 3x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
16 15 14 13
Richtek products are :
`
RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.
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Suitable for use in SnPb or Pb-free soldering processes.
TS
BAT
BAT
EN
1
12
2
11
GND
3
JG = : Product Code
JG=YM
DNN
YMDNN : Date Code
DS9525-01 May 2011
6
7
9
8
EN2
EN1
PGOOD
GND
5
Marking Information
10
17
4
NC
SYS
SYS
CHG
WQFN-16L 3x3
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1
RT9525
Typical Application Circuit
RT9525
Adapter or USB
13 VIN
CIN
2.2µF
10, 11
CSYS
10µF
15
Disconnect
Connect
CTIMER
1µF
2, 3
CBAT
1µF
+
SYS
4 EN
Chip Enable
BAT
SYSOFF
14 TIMER
TS 1
ISETA 16
GND
6 EN1
5 EN2
RISETA
8, 17 (Exposed Pad)
PGOOD 7
9
CHG
Functional Pin Description
Pin No.
Pin Name
Pin Function
Thermistor Monitor Input. The TS pin connects to a battery’s thermistor to
determine if the battery is too hot or too cold to charge. If the battery’s temperature
is out of range, charging is paused until it re-enters the valid range. TS also detect
whether the battery (with NTC) is present or not
1
TS
2, 3
BAT
Battery Connect Pin.
4
EN
Charge Enable, Active-low input. 200kΩ pull low.
5
EN2
6
EN1
7
PGOOD
8,
GND
17 (Exposed Pad)
9
CHG
Input Current Limit Configuration Setting.
12
NC
Power Good Status Output. Active-low, open-drain output.
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
Charger Status Output. Active-low, open-drain output.
System Connect Pin. Connect this pin to system load with a minimum 10uF MLCC
to GND.
No Internal Connection.
13
VIN
Supply Voltage Input.
14
TIMER
15
SYSOFF
16
ISETA
Safe Charge Timer Setting.
System Disconnect Pin. Pull SYSOFF high to disconnect SYS from battery,
connect to GND for normal operation. Internally pulled up by 1μA current source to
BAT.
Charge Current Set Input. Connect a resistor (RISETA) between ISET and GND.
10, 11
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SYS
DS9525-01 May 2011
RT9525
Function Block Diagram
VIN
SYS
Control
Circuit
BAT
1µA
Sleep
Mode
ISETA
EN1
EN2
EN
Current
Set Block
200k
Thermal
Circuit
Timer
TIMER
200k
Logic
200k
OVP
UVLO
DS9525-01 May 2011
SYSOFF
CC/CV/TR
/APPM
Multi Loop
Controller
TS
TS
CHG
PGOOD
GND
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3
RT9525
Absolute Maximum Ratings
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(Note 1)
Supply Input Voltage, VIN -----------------------------------------------------------------------------------------------CHG, PGOOD -------------------------------------------------------------------------------------------------------------Other Pins ------------------------------------------------------------------------------------------------------------------CHG, PGOOD Continuous Current -----------------------------------------------------------------------------------BAT Continuous Current (total in two pins) (Note 2) -----------------------------------------------------------Power Dissipation, PD @ TA = 25°C
WQFN-16L 3x3 -----------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 3)
WQFN-16L 3x3, θJA ------------------------------------------------------------------------------------------------------WQFN-16L 3x3, θJC -----------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 4)
HBM (Human Body Mode) ---------------------------------------------------------------------------------------------MM (Machine Mode) ------------------------------------------------------------------------------------------------------
Recommended Operating Conditions
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−0.3V to 28V
−0.3V to 28V
−0.3V to 6V
20mA
2.5A
1.471W
68°C/W
7.5°C/W
260°C
150°C
−65°C to 150°C
2kV
200V
(Note 5)
Supply Input Voltage, VIN (EN2 = H, EN1 = L) --------------------------------------------------------------------Supply Input Voltage, VIN (EN2 = L, EN1 = X) --------------------------------------------------------------------Junction Temperature Range -------------------------------------------------------------------------------------------Ambient Temperature Range --------------------------------------------------------------------------------------------
4.45V to 6V
4.65V to 6V
−40°C to 125°C
−40°C to 85°C
Electrical Characteristics
(VIN = 5V, VBAT = 4V, TA = 25°C, unless otherwise specification)
Parameter
Supply Input
VIN Operating Range
VIN Under Voltage Lockout
Threshold
VIN Under Voltage Lockout
Hysteresis
Symbol
Test Conditions
VUVLO
VUVLO _hys
Min
Typ
Max
Unit
4.2
--
6
V
3.1
3.3
3.5
V
--
240
--
mV
---
1
0.8
2
1.5
mA
--
195
333
μA
--
5
15
μA
VIN Supply Current
I IN
VIN Suspend Current
I SUS
ISYS = IBAT = 0mA, EN = L
ISYS = IBAT = 0mA, EN = H
VIN = 5V, EN2 = EN1 = H
BAT Sleep Leakage Current
I SLEEP
VBAT > VIN , (VIN = 0V)
VIN − BAT VOS Rising
VOS_H
--
200
300
mV
VIN − BAT VOS Falling
VOS_L
10
50
--
mV
4.16
4.2
4.23
V
5.3
5.5
5.7
V
Voltage Regulation
Battery Regulation Voltage
VREG
System Regulation Voltage
VSYS
0 to 85°C, ILOAD = 20mA
APPM Regulation Voltage
VAPPM
EN2 = L ,EN1 = H
DPM Regulation Voltage
VDPM
EN2 = L
VIN to VSYS MOSFET Ron
RDS(ON)
ILIM = 1000mA
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4.2
4.3
4.4
V
4.35
4.5
4.63
V
--
0.2
0.35
Ω
To be continued
DS9525-01 May 2011
RT9525
Parameter
Symbol
Test Conditions
BAT to VSYS MOSFET Ron
RDS(ON)
VBAT = 4.2V,ISYS = 1A
Re-charge threshold
ΔVREGCGG
Battery Regulation –
Recharge-level
ISETA Set Voltage (Fast
Charge Phase)
VISETA
VBATT = 4V, RISETA = 1kΩ
VIN Charge Setting Range
I CHG
VIN Charge Current
I CHG
VIN Current Limit
I LIM
Min
Typ
Max
Unit
--
0.05
0.1
Ω
120
200
280
mV
--
2
--
V
100
--
1200
mA
Current Regulation
VBATT = 4V, RISETA = 1kΩ
EN2 = H, EN1 = L (1.5A mode)
EN2 = L, EN1 = H (500mA
mode)
EN2 = L, EN1 = L (100mA
mode)
570
1.2
600
1.5
630
1.8
mA
A
450
475
500
mA
80
90
100
mA
BAT Falling
2.75
2.85
2.95
V
--
200
--
mV
5
10
15
%
10
20
30
%
EN2 = L, EN1 = L
--
3.3
--
%
VCHG
ICHG = 5mA
--
200
--
mV
VPGOOD
IPGOOD = 5mA
--
200
--
mV
1.5
--
---
0.4
V
TREG
--
125
--
°C
TSD
--
155
--
°C
ΔTSD
--
20
--
°C
6.25
6.5
6.75
V
--
100
--
mV
--
300
--
mV
1440
11520
1800
14400
2160
17280
s
s
--
1.2
--
ms
--
50
--
μs
Pre-Charge
BAT Pre-Charge Threshold
VPRECH
BAT Pre-Charge Threshold
ΔVPRECH
Hysteresis
Pre-Charge Current
I PRECH
Charge Termination Detection
Termination Current Ratio to
I TERM
Fast Charge
Termination Current Ratio to
I TERM2
Fast Charge USB100mA
Login Input/Output
CHG Pull Down Voltage
PGOOD Pull Down Voltage
EN, EN1,EN2, SYSOFF Pin
Threshold
Protection
Thermal Regulation
Thermal Shutdown
Temperature
Thermal Shutdown Hysteresis
VBAT = 2V
VIH
VIL
OVP SET Voltage
VOVP
VIN Rising
OVP Hysteresis
Output Short Circuit Detection
Threshold
Time
Pre-Charge Fault Time
Fast charge Fault Time
VOVP_hys
VSHORT
VBAT − VSYS
t PCHG
t FCHG
PGOOD Deglitch Time
t PGOOD
CTIMER = 1μF (1/8 x tFCHG)
CTIMER = 1μF
Time measured from
VIN : 0Æ5V
1μs rise-time to PGOOD = L
Input Over Voltage Blanking
Time
t OVP
To be continued
DS9525-01 May 2011
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5
RT9525
Parameter
Pre-Charge to Fast-Charge
Deglitch Time
Fast-Charge to Pr-Charger
Deglitch Time
Termination Deglitch Time
Recharge Deglitch Time
Input Power Loss to SYS LDO
Turn-Off Delay Time
Packing Temperature Fault
Detection Deglitch Time
Short Circuit, Deglitch Time
Short Circuit Recovery Time
Symbol
Test Conditions
Min
Typ
Max
Unit
tPF
--
25
--
ms
tfp
--
25
--
ms
tTERMI
--
25
--
ms
tRECHG
--
100
--
ms
tNO-IN
--
25
--
ms
tTS
--
25
--
ms
tSHORT
--
250
--
μs
64
--
ms
tSHORT_R
Other
NT C Bias Current
INTC
VIN > UVLO and
VIN > VB AT + V OS_H
72
75
78
μA
High Temperature Trip Point
High Temperature Trip Point
Hysteresis
Low Temperature Trip Point
VHOT
VTS Falling
270
300
330
mV
VHOT_h ys
VTS Rising from V HOT
--
30
--
mV
VCOLD
VTS Rising
2000
2100
2200
mV
VCOLD_hys
VTS Falling from VCOLD
--
300
--
mV
Low Temperature Trip Point
Hysteresis
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. Guaranteed by design.
Note 3. θJA is measured in natural convection at TA = 25°C on a high-effective thermal conductivity four-layer test board of
JEDEC 51-7 thermal measurement standard. The measurement case position of θJC is on the exposed pad of the
package.
Note 4. Devices are ESD sensitive. Handling precaution is recommended.
Note 5. The device is not guaranteed to function outside its operating conditions.
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DS9525-01 May 2011
RT9525
Typical Operating Characteristics
SYSOFF On/Off Without Input Power
Charger Detect Sequence
V SYSOFF
(5V/Div)
VBAT
(5V/Div)
V SYS
(5V/Div)
IBAT
(500mA/Div)
EN
(5V/Div)
CHG
(5V/Div)
VBAT
(2V/Div)
IBAT
(500mA/Div)
VIN = NC, VBAT = 3.7V, 1.5A Mode,
RISETA = 1kΩ, RSYS = 10kΩ
VIN = 5V, VBAT = 3.7V, 1.5A Mode, RISETA = 1kΩ
Time (10ms/Div)
Time (5ms/Div)
SYSOFF On/Off With Input Power
OVP Fault
V IN
V SYSOFF
(5V/Div)
VBAT
(5V/Div)
V SYS
(5V/Div)
IBAT
(200mA/Div)
VIN
(10V/Div)
VSYS
VBAT
V SYS
(2V/Div)
IBAT
(500mA/Div)
VIN = 6V, VBAT = 3.7V, 1.5A Mode, RISETA = 1kΩ
VBAT
(1V/Div)
Time (5ms/Div)
Load Transient Response
VIN
(10V/Div)
I IN
(1A/Div)
V SYS
(5V/Div)
I SYS
(2A/Div)
VBAT
(5V/Div)
IBAT
(2A/Div)
IBAT
VIN = 5V to 15V, VBAT = 3.7V,
1.5A Mode, RISETA = 1kΩ, RSYS = 10Ω
Time (50μs/Div)
Charger CHG Status After Safety Timers Expired
CHG
(2V/Div)
VIN
(5V/Div)
APPM, 1.5A Mode, VIN = 5V, VBAT = 3.7V
RISETA = 1kΩ, ISYS = 0 to 2A
Time (1ms/Div)
DS9525-01 May 2011
VBAT
(2V/Div)
IBAT
(500mA/Div)
VIN = 5V, VBAT = 3.7V, RISETA = 620Ω
Time (250μs/Div)
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RT9525
VSYS Short to GND Protection with Battery
Battery Current vs. Charging Time
0.6
Battery Current (A)
0.5
VBAT
(1V/Div)
V SYS
(1V/Div)
0.4
0.3
0.2
0.1
VBAT = 3.7V, VSYS = GND
VIN = 5V, 500mA Mode
0
0
Time (25ms/Div)
2000
4000
6000
8000
10000
Charging Time (s)
Battery Voltage vs. Charging Time
Charging Current vs. Battery Voltage
700
4.5
VIN = 5V, RISETA = 1kΩ
600
Charging Current (mA)1
Battery Voltage (V)
3.6
2.7
1.8
0.9
500
400
300
1.5A Mode, VIN = 4.5V
1.5A Mode, VIN = 5V
1.5A Mode, VIN = 6V
500mA Mode, VIN = 5V
200
100
VIN = 5V, 500mA Mode
0
0
0
2000
4000
6000
8000
2
10000
2.5
Charging Current vs. RISETA
4
VIN = 5V, VBAT = 3.7V
1000
800
600
400
200
0
5.53
5.50
5.48
VOUT @ 0A (V)
VOUT @ 0.5A (V)
VOUT @ 1A (V)
5.45
5.43
5.40
5.38
VIN = 5V
5.35
0
1000
2000
3000
RISETA ((Ω))
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4000
5000
4.5
Output Regulation Voltage vs. Temperature
1200
Charging Current (mA)1
3.5
5.55
Output Regulation Voltage (V)1
1400
3
Battery Voltage (V)
Charging Time (s)
6000
-50
-25
0
25
50
75
100
125
Temperature (°C)
DS9525-01 May 2011
RT9525
Dropout Voltage (In-Out) vs. Temperature
OVP Threshold Voltage vs. Temperature
450
VBAT = 3.7V
400
6.51
Dropout Voltage (mV)1
OVP Threshold Voltage (V)
6.54
Rising
6.48
6.45
6.42
6.39
Falling
6.36
350
300
250
200
150
100
50
VIN = 5V, ISYS = 1A
0
6.33
-50
-25
0
25
50
75
100
-50
125
-25
0
50
75
100
125
Charger Current vs. Temperature
Dropout Voltage (Bat-Out) vs. Temperature
70
550.00
60
481.25
Charger Current (mA)1
Dropout Voltage (mV)
25
Temperature (°C)
Temperature (°C)
50
40
30
20
10
412.50
343.75
275.00
206.25
137.50
68.75
VIN = 3.7V, ISYS = 1A
0
-50
-25
0
25
50
75
Temperature (°C)
DS9525-01 May 2011
100
125
0.00
VIN = 5V, VBAT = 3.7V, 500mA Mode
-50
-25
0
25
50
75
100
125
Temperature (°C)
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9
RT9525
Application Information
The RT9525 is a fully integrated single cell Li-ion battery
charger ideal for portable applications. The internal thermal
feedback circuitry regulates the die temperature to optimize
the charge rate for all ambient temperatures. Other features
include under voltage protection and over voltage
protection.
Pre-Charge Mode
When the output voltage is lower than 2.8V, the charging
current will be reduced to a fast charge current ratio set
by RISETA to protect the battery life time.
Fast Charge Mode
When the output voltage is higher than 3V, the charging
current will be equal to the fast charge current set by
RISETA.
Constant Voltage Mode
When the output voltage is near 4.2V and the charging
current falls below the termination current, after a deglitch
time check of 25ms, the charger will become disabled
and CHG will go from L to H.
During the fast charge phase, several events may increase
the timer duration.
For example, the system load current may have activated
the APPM loop which reduces the available charging
current, the device has entered thermal regulation because
the IC junction temperature has exceeded TREG.
During each of these events, if 3V < VBAT < 4V, the internal
timers are slowed down proportionately to the reduction
in charging current. However, once the duration exceeds
the fault time, the CHG output will flash at approximately
2Hz to indicate a fault condition and a charger current ~
1mA.
2
tFCHG_true = tFCHG x
VISETA
tFCHG_true : modified timer in fast charge
tFCHG : original timer in fast charge
C
tFCHG = 14400 sec x ( TIMER )
1μF
tFCHG
tPCHG =
8
tPCHG : timer in pre-charge
Time fault release :
(1) Re-plug power
Re-Charge Mode
When the chip is in charge termination mode, the charging
current will gradually go down to zero. However, once the
voltage of the battery drops to below 4V, there will be a
deglitch time of 100ms, and then the charging current will
resume again.
Charging Current Decision
The charge current can be set according to the following
equations :
ICHG_FAST = VISETA / RISETA x 300 (A)
ICHG_PRE = 10% x ICHG_FAST
(A)
where VISETA unit = V; RISETA unit = Ω
Time Fault
The Fast Charge Fault Time can be set according to the
following equations :
(2) Toggle /EN
(3) Enter/Exit USB suspend mode
(4) Removes Battery
(5) OVP
Note that the fast charge fault time is independent of the
charge current.
Power Good
VIN Power Good (PGOOD = L)
Input State
VIN < VUVLO
PGOOD Output
High impedance
VUVLO < VIN < VBAT + VOS_H
High impedance
VBAT + VOS_H < VIN < VOVP
VIN > VOVP
Low impedance
High impedance
Fast Charge Fault Time : tFCHG = 14400 x CTIMER (s)
Pre-Charge Fault Time : tPCHG = 1/8 x tFCHG (s)
where CTIMER unit is μF.
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DS9525-01 May 2011
RT9525
Charge State Indicator
Charge State
Charging
Charging suspended by thermal
loop
Safety timers expired
Charging done
Recharging after termination
IC disabled or no valid input
power
From (1), (2), the RT1 and RT2 can be calculated by the
following equations :
CHG Output
Low (for first charge
cycle)
2Hz flash
RT1 =
−1500μ × (RHOT + RCOLD )
+
3000μ
20 5625μ 2 x (RCOLD − RHOT )2 + 105μ × (RCOLD − RHOT )
3000μ
High impedance
RT2 =
(RT1 + RHOT )
250μ × RT1 + 250μ × RHOT − 1
Battery Pack Temperature Monitoring
Charge Enable
The RT9525 features an external battery pack temperature
monitoring input. The TS input connects to the NTC
thermistor in the battery pack to monitor battery
temperature and prevent dangerous over temperature
conditions. If at any time the voltage at TS falls outside of
the operating range, charging will be suspended. The
timers maintain their values but suspend counting. When
charging is suspended due to a battery pack temperature
fault, the CHG pin remains low and continues to indicate
charging.
When EN is low, the charger turns on. When EN is high,
the charger turn off. EN is pulled low for initial condition.
VIN Input Current Limit
EN2
EN1
VIN Input Current Limit
L
L
90mA
L
H
475mA
H
L
1.5A
H
H
Suspend Mode
Suspend Mode
Set EN1 = EN2 = H, and the charger will enter Suspend
Mode. In Suspend Mode, CHG is in high impedance and
ISUS(MAX) < 330μA.
2.1V
-
RT1
TS
RNTC
RT2
+
-
0.3V
+
Too Cold
Power Switch
Too Hot
For the RT9525, there are three power scenarios :
(1) When a battery and an external power supply
(USB or adapter) are connected simultaneously :
Figure 1
When temperature reaches at “Too Cold” state,
RNTC = RCOLD
(RT1 + RCOLD ) × RT2
× INTC = 2.1V (V)
(RT1 + RCOLD ) + RT2
(1)
where INTC = 75μ A (typ.)
When temperature reaches at “Too Hot” state,
RNTC = RHOT
(RT1 + RHOT ) × RT2
× INTC = 0.3V (V)
(RT1 + RHOT ) + RT2
If the system load requirements exceed that of the
input current limit, the battery will be used to
supplement the current to the load. However, if the
system load requirements are less than that of the
input current limit, the excess power from the external
power supply will be used to charge the battery.
(2) When only the battery is connected to the system :
The battery provides the power to the system.
(2)
(3) When only an external power supply is connected to
the system :
The external power supply provides the power to the
system.
DS9525-01 May 2011
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11
RT9525
Input DPM Mode
Thermal Regulation and Thermal Shutdown
For the RT9525, the input voltage is monitored when the
USB100 or USB500 is selected. If the input voltage is
lower than VDPM, the input current limit will be reduced to
stop the input voltage from dropping any further. This can
prevent the IC from damaging improperly configured or
inadequately designed USB sources.
The RT9525 provides a thermal regulation loop function
to monitor the device temperature. If the die temperature
rises above the regulation temperature, TREG, the charge
current will automatically be reduced to lower the die
temperature. However, in certain circumstances (such as
high VIN, heavy system load, etc.) even with the thermal
loop in place, the die temperature may still continue to
increase. In this case, if the temperature rises above the
thermal shutdown threshold, TSD, the internal switch
between VIN and SYS will be turned off. The switch
between the battery and SYS will remain on, however, to
allow continuous battery power to the load. Once the die
temperature decreases by ΔTSD, the internal switch
between VIN and SYS will be turned on again and the
device returns to normal thermal regulation.
APPM Mode
Once the sum of the charging and system load currents
becomes higher than the maximum input current limit,
the SYS pin voltage will be reduced. When the SYS pin
voltage is reduced to VAPPM, the RT9525 will automatically
operate in APPM mode. In this mode, the charging current
is reduced while the SYS current is increased to maintain
system output. In APPM mode, the battery termination
function is disabled.
Battery Supplement Mode Short Circuit Protect
In APPM mode, the SYS voltage will continue to drop if
the charge current is zero and the system load increases
beyond the input current limit. When the SYS voltage
decreases below the battery voltage, the battery will kick
in to supplement the system load until the SYS voltage
rises above the battery voltage.
While in supplement mode, there is no battery supplement
current regulation. However, a built in short circuit
protection feature is available to prevent any abnormal
current situations. While the battery is supplementing the
load, if the difference between the battery and SYS voltage
becomes more than the short circuit threshold voltage,
SYS will be disabled. After a short circuit recovery time,
tSHORT_R, the counter will be restarted. In supplement
mode, the battery termination function is disabled. Note
that for the battery supply mode exit condition, VBAT −
VSYS < 0V.
Battery Disconnect (SYSOFF input)
The RT9525 features a SYSOFF input that allows the
user to turn off the switch to disconnect the battery from
the SYS pin.
www.richtek.com
12
4.16 to 4.2 to 4.23V
-40 to 85°C
Battery Voltage
Charging Current
VRECH
(EN2,EN1) = (H, L) or (L, H)
ITERMI = 20% x ICHG-FAST
VPRECH
ITERM
(EN2, EN1) = (L, H)
ITERMI = 3.3% x
ICHG_FAST
ITERM2
ICHG_PRE = I0% x ICHG_FAST
Time
APPM Profile
1.5A Mode
VIN 6V
VSYS 5.5V
VADPM 4.3V
VBAT 4.0V
3A
2A
IBAT
1A
ISYS
0
IVIN -1A
-2A
-3A
T1
T2
T3
T4
T5
T6
T7
DS9525-01 May 2011
RT9525
Thermal Considerations
ISYS
VSYS
T1, T7
0
SYS Regulation Voltage
T2, T6
< I VIN_OC
− CHG_MAX
SYS Regulation Voltage
T3, T5
> IVIN_OC
− CHG_MAX
< IVIN_OC
Auto Charge Voltage
Threshold
T4
> I VIN_OC
VBAT − IBAT x RDS(ON)
I VIN
IBAT
CHG_MAX
CHG_MAX
For continuous operation, do not exceed absolute
maximum junction temperature. The maximum power
dissipation depends on the thermal resistance of the IC
package, PCB layout, rate of surrounding airflow, and
difference between junction and ambient temperature. The
maximum power dissipation can be calculated by the
following formula :
PD(MAX) = (TJ(MAX) − TA) / θJA
T2, T6 ISYS + CHG_MAX
where TJ(MAX) is the maximum junction temperature, TA is
the ambient temperature, and θJA is the junction to ambient
thermal resistance.
CHG_MAX
T3, T5
VIN_OC
VIN_OC − I SYS
T4
VIN_OC
ISYS − IVIN_OC
For recommended operating condition specifications of
the RT9525, the maximum junction temperature is 125°C
and TA is the ambient temperature. The junction to ambient
thermal resistance, θJA, is layout dependent. For WQFN-
USB 500mA Mode
VUSB
VSYS
VAPPM
VBAT
16L 3x3 packages, the thermal resistance, θJA, is 68°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 :
5V
4.3V
4.0V
PD(MAX) = (125°C − 25°C) / (68°C/W) = 1.471W for
WQFN-16L 3x3 package
0.75A
0.5A
IBAT 0.25A
0
ISYS
IUSB -0.25A
-0.5A
-0.75A
T1
T1, T7
T2, T6
T3, T5
T4
T1, T7
T2
T3
T4
T5
T6
T7
ISYS
0
< USB_OC
− CHG_MAX
> USB_OC
− CHG_MAX
< USB_OC
VSYS
SYS Regulation Voltage
> USB_OC
VBAT − IBAT x RDS(ON)
SYS Regulation Voltage
Auto Charge Voltage
Threshold
IUSB
IBAT
CHG_MAX
CHG_MAX
T2, T6 ISYS + CHG_MAX
CHG_MAX
T3, T5
USB_OC
USB_OC − ISYS
T4
USB_OC
ISYS − USB_OC
The maximum power dissipation depends on the operating
ambient temperature for fixed T J(MAX) and thermal
resistance, θJA. For the RT9525 package, the derating
curve in Figure 2 allows the designer to see the effect of
rising ambient temperature on the maximum power
dissipation.
1.60
Maximum Power Dissipation (W)1
T1, T7
Four-Layer PCB
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 2. Derating Curve for the RT9525 Package
DS9525-01 May 2011
www.richtek.com
13
RT9525
Layout Considerations
The RT9525 is a fully integrated low cost single cell Li-Ion
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 RT9525.
`
Input and output capacitor should be placed close to IC and
connected to ground plane. The trace of input in 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 R ISETA should be isolated from other
noisy traces. A short wire is recommended to prevent EMI
and noise coupling.
GND
RISETA
GND
CBAT
BATT
RTS
CTIMER
ISETA
SYSOFF
TIMER
VIN
The RISETA connection
copper area should be
minimized and kept far
away from noise sources.
Place CIN near
the IC to improve
performance.
GND
CIN
16 15 14 13
TS
BAT
BAT
EN
1
12
2
11
GND
3
10
17
4
6
7
9
CSYS
SYS
8
EN2
EN1
PGOOD
GND
5
NC
SYS
SYS
CHG
GND should be connected to a
strong ground plane for heat
sinking and noise protection.
SYS
Figure 3. PCB Layout Guide
www.richtek.com
14
DS9525-01 May 2011
RT9525
Outline Dimension
D
SEE DETAIL A
D2
L
1
E
E2
e
b
A
A1
1
1
2
2
DETAIL A
Pin #1 ID and Tie Bar Mark Options
A3
Note : The configuration of the Pin #1 identifier is optional,
but must be located within the zone indicated.
Symbol
Dimensions In Millimeters
Dimensions In Inches
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
0.180
0.300
0.007
0.012
D
2.950
3.050
0.116
0.120
D2
1.300
1.750
0.051
0.069
E
2.950
3.050
0.116
0.120
E2
1.300
1.750
0.051
0.069
e
L
0.500
0.350
0.020
0.450
0.014
0.018
W-Type 16L QFN 3x3 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.
DS9525-01 May 2011
www.richtek.com
15