Preliminary
y
RT9541
Li-Ion Battery Protector
General Description
The RT9541 Series are protection ICs for over-
charge/discharge of rechargeable one-cell Lithium-ion
(Li+) batteries by CMOS process.
The RT9541 Series can detect over-charge/discharge
of Li+ one-cell and excess load current and charge
current, further include a short circuit protector for
preventing large external short circuit current.
Each of these ICs is composed of four voltage
detectors, a reference unit, a hysteresis circuit, and a
bidirectional short circuit protector. Package of SOT-
26 is available.
Ordering Information
RT9541
Package type
E : SOT-26 Type I
ER : SOT-26 T
pe II
Operating temperature range
C: Commercial standard
See Table 1
Typical Application Circuit
R2
1K
+
Ω
R1
100
Ω
C1
0.1µF
C3
0.01µF
CT
VSS DOUT
C2
0.1µF
RT9541
VDD
V-
COUT
Features
z
Low supply current
−
Supply current: TYP. 2.0µµµµA
−
Standby current (after detecting over-
discharge): Less than 0.2µµµµA
z
High accuracy detector threshold
−
Over-charge detector: ±±±±25mV
−
Over-discharge detector: ±±±±2.5%
z
Built-in protection circuit
−
Excess current trip/Short circuit protector in
both charging and discharging direction
z
Output delay of over-charge adjustable with
an external capacitor: 75mS at 0.01µµµµF
z
Ultra small package: SOT26
Applications
Over-charge / Over-discharge Protection for Li+
z
One-cell Pack
z High Precision Protectors for Cellular Phones or
Instruments Using Li+ One-cell Battery
Pin Configurations
Part Number Pin Configurations
RT9541CE
(Plastic SOT-26)
RT9541CER
(Plastic SOT-26)
64
5
321
64
5
321
TOP VIEW
1. COUT
2. CT
3. VSS
4. DOUT
5. VDD
6. V-
TOP VIEW
1. DOUT
2. V-
3. COUT
4. CT
5. VDD
6. VSS
DS9541-05 August 2001 www.richtek-ic.com.tw
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RT9541
Preliminary
Absolute Maximum Ratings
z Allowable Battery Voltage -0.3V ~ 7V
z Input Voltage (V) VDD-14V to VDD +0.3V
z Input Voltage (CT) VSS-0.3V to VDD +0.3V
z Output Voltage (COUT) VDD-14V to VDD +0.3V
z Output Voltage (DOUT) VSS-0.3V to VDD +0.3V
z Power Dissipation, P
@ TA = 25°C
D
SOT-26 0.25W
z Package Thermal Resistance
SOT-26, θ
z Operating Temperature Range -20°C ~ +85°C
z Storage Temperature Range -65°C ~ +150°C
JA
250°C/W
Electrical Characteristics
Parameter Symbol Test Conditions Min Typ Max Units
Operating Input Voltage
Charger Voltage
Minimum Operating Voltage for 0V
Charging
Accuracy of Over-charge
Threshold Voltage
V
V
∆V
DD
CHG
OCHG
Voltage defined as VDD-VSS 1 -- 6 V
Voltage defined as VDD-V- -- -- 14 V
Voltage defined as VDD-VVDD-VSS = 0V
Detect rising edge of supply
voltage
-- -- 1 V
-25 -- 25 mV
Over-charge Threshold Hysteresis 0.1 0.15 0.2 V
Output Delay Time of Over-charge
Accuracy of Over-discharge
Threshold Voltage
Output Delay Time of Overdischarge
Excess Current Threshold Voltage
During Discharge
Output Delay of Discharge Excess
Current
Excess Current Threshold Voltage
During Charge
T
OCHG
∆V
ODISCHG
T
ODISCHG
C3 = 0.01µF, VDD = 3.6V ~
4.3V
Detect falling edge of supply
voltage
30 60 80 mS
-2.5 -- 2.5
VDD = 3.6V ~ 2.4V 10 15 20
Detect rising edge of “V-“ pin
voltage
0.15 0.17 0.19
VDD = 3.0V 15 20 25
Detect falling edge of “V-“ pin
voltage
-0.19 -0.17 -0.15
mS
mS
%
V
V
Output Delay of Charge Excess
Current
Short Detection Voltage During
Discharge
Output Delay of Discharge Short
Circuit
Reset Resistance for Excess
Current Protection
Supply Current
Standby Current
www.richtek-ic.com.tw DS9541-05 August 2001
T
SHORT
R
SHORT
I
DD
I
STANDBY
VDD = 3.0V VDD-1.1 VDD-0.8 VDD-0.5
VDD = 3.0V -- 5 50
VDD = 3.6V, V- = 1.0V 25 50 75
VDD = 3.9V, V- = 0V -- 2.0 5.0
VDD = 2.0V -- 0.1 0.5
15 20 25
mS
V
µS
kΩ
µA
µA
2
Table 1
Preliminary
RT9541
Part Number
RT9541ACE (R) 4.25V 2.3V 170mV
RT9541BCE (R) 4.25V 2.4V 170mV
RT9541CCE (R) 4.25V 2.5V 170mV
RT9541DCE (R) 4.25V 2.6V 170mV
RT9541ECE (R) 4.25V 2.7V 170mV
RT9541FCE (R) 4.25V 2.8V 170mV
RT9541GCE (R) 4.30V 2.3V 170mV
RT9541HCE (R) 4.30V 2.4V 170mV
RT9541ICE (R) 4.30V 2.5V 170mV
RT9541JCE (R) 4.30V 2.6V 170mV
Over
Charge
Over
Discharge
Excess
Current
Function Block Diagram
VDD CT
Part Number
RT9541KCE (R) 4.30V 2.7V 170mV
RT9541LCE (R) 4.30V 2.8V 170mV
RT9541MCE (R) 4.35V 2.3V 170mV
RT9541NCE (R) 4.35V 2.4V 170mV
RT9541OCE (R) 4.35V 2.5V 170mV
RT9541PCE (R) 4.35V 2.6V 170mV
RT9541QCE (R) 4.35V 2.7V 170mV
RT9541RCE (R) 4.35V 2.8V 170mV
RT9541SCE (R) 4.35V 2.9V 170mV
RT9541TCE (R) 4.25V 2.9V 170mV
Over
Charge
Over
Discharge
Excess
Current
Pin Description
Pin Number
RT9541-CE RT9541-CER
1 3 COUT Output of Over-charge Detection, CMOS Output
2 4 CT Pin for External Capacitor Setting Output Delay of VD1
3 6 VSS Ground
4 1 DOUT Output of Over-discharge Detection, CMOS Output
_
+
VD1
VD2
VSS
Pin Name Pin Function
+
_
VD4
_
+
+
_
VD3
Delay
Level Shift
Short
Cir cuit
Detector
DOUT COU T V-
5 5 VDD Power Supply, through a Resistor (R1)
6 2 V- Pin for Charger Negative Input, through a Resistor (R2)
DS9541-05 August 2001 www.richtek-ic.com.tw
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RT9541
Applications Information
(1) Operation Description
Preliminary
Refering to the “Function Block Diagram”, when
charging voltage crosses the detector threshold from
a low value to a value higher than VDET1, the output
of COUT pin, the output of over-charge detector/VD1,
swiches to low level,..charger’s negative pin level.
After detecting over-charge the VD1 can be reset and
the output of COUT pin becomes “H” when the VDD
voltage is coming down to a level lower than “VDET1
– VHYS1”, or when a charger is disconnected from
the battery pack.
The output of DOUT pin, the output of over-discharge
detector/VD2, switches to “L” after internally fixed
delay time passed, when discharging voltage crosses
the detector threshold from a high value to a value
lower than VDET2. An excess load current can be
sensed and cut off after internally fixed delay time
passsed through the built in excess current detector,
VD3, with DOUT being enabled to low level. Once
after detecting excess current, the VD3 is released
and DOUT level switches to “H” by detaching a
battery pack from a load system.
Futher, short circuit protector makes DOUT level to
“L” immediately with external short circuit current and
removing external short circuit leads DOUT level to
“H”.
The excess charging current is also monitored, and
the charging path will be cut off (by turn low COUT)
after excess charging current was detected lasting a
internally fixed delay time. The charging path will be
re-started (by turn high COUT) after another
internally fixed delay. If the excess charging current is
still there, the same process will be repeated and
cause the charging path toggling on and off with a
12.5% on duty. Such a protection function reduces
the average charging current to 12.5% of original
value when excess charging current detected.
The short circuit protection function in charging
direction was also provided. When COUT high and
the “V-“ pin voltage 5V lower than VSS pin, the
RT9541 will turn low COUT with a fixed delay. The
COUT will go high after the short circuit condition
was removed.
After detecting over-discharge, supply current will be
kept extremely low by halting some internal circuits
operation. The output delay of over-charge detectors
can be set by connecting an external capacitor.
Output type of COUT and DOUT are CMOS.
(2) Component Selection Guide:
Referring to “Typical Application Circuit”, R1 and
C1 will stabilize a supply voltage to the RT9541. A
recommended R1 value is less than 1kΩ. A larger
value of R1 leads higher detection voltage, makes
some errors, because of shoot through current
flowed in the RT9541.
R2 and C2 will stabilize a V- pin voltage. The
resetting from over-discharge with connecting
charger possibly be disabled by larger value of R2.
Recommended value is less than 1kΩ. And
recommended C2 value is less than 1µF.
R1 and R2 can operate as a current limiter against
setting cell reverse direction or for applying excess
charging voltage to the RT9541. While smaller R1
and R2 may cause an over power dissipation rating
of the RT9541 and a total of “R1+R2” should be
more than 1kΩ.
www.richtek-ic.com.tw DS9541-05 August 2001
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Timing Diagram
RT9541-CE/CER
Preliminary
RT9541
DS9541-05 August 2001 www.richtek-ic.com.tw
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RT9541
Package Information
Preliminary
D
C
b
A
e
Dimensions In Millimeters Dimensions In Inches
Symbol
Min Max Min Max
A 0.889 1.295 0.035 0.051
A1 -- 0.152 -- 0.006
B 1.397 1.803 0.055 0.071
B
A1
H
L
b 0.356 0.559 0.014 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 0.102 0.254 0.004 0.010
L 0.356 0.610 0.014 0.024
www.richtek-ic.com.tw DS9541-05 August 2001
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Preliminary
RT9541
DS9541-05 August 2001 www.richtek-ic.com.tw
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RT9541
Preliminary
RICHTEK TECHNOLOGY CORP.
Headquarter
6F, No. 35, Hsintai Road, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5510047 Fax: (8863)5537749
www.richtek-ic.com.tw DS9541-05 August 2001
RICHTEK TECHNOLOGY CORP.
Taipei Office (Marketing)
8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City
Taipei County, Taiwan, R.O.C.
Tel: (8862)89191466 Fax: (8862)89191465
Email: marketing@richtek-ic.com.tw
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