Application Note: SY6981
High Efficiency, 1.2A
Two-cell Boost Li-Ion Battery Charger
General Description
SY6981 is a 3.6-5.5V
IN
, 1.2A two-cell synchronous
Boost Li-Ion battery charger which integrates 1MHz
switching frequency and full protection functions. The
charge current up to 1.2A can be programmed by using
the external resistor for different portable applications
and indicates the charger current information
simultaneously. It also has a programmable charge
timeout for safety battery charge operation and a
programmable input voltage threshold for adaptive
input current limit. SY6981 can disconnect output
when there is an output short circuit or shutdown. It
consists of 18V rating FETs with extremely low on
resistance to achieve high charge efficiency and simple
peripheral circuit design.
SY6981 along with small QFN3×3 footprint provides
small PCB area application.
Features
Low Profile QFN3×3 Package
Integrated Synchronous Boost with 18V Rating
Low R
DSON
FETs for High Charge Efficiency
Trickle Current / Constant Current / Constant
Voltage Charge Mode
Programmable Input Voltage Threshold for
Adaptive Current Limit.
Maximum 1.2A Constant Charge Current
Charge Current Information Indication.
Programmable Charge Timeout
Programmable Constant Charge Current
Selectable Constant Voltage
±0.5%
Battery Voltage Accuracy
Thermal Regulation Protection
External Shutdown Function
Input Voltage UVLO and OVP
Over Temperature Protection
Output Short Circuit Protection
Charge Status Indication
Normal Synchronous Boost Operation When the
Battery is Removed
Ordering Information
SY6981
□
(□□
□
□□)□
□□
Tempera ture Code
Packa ge Code
Optiona l Spec Code
Applications
Cellular Telephones, PDA, MP3 Players, MP4
Players
Digital Cameras
Bluetooth Applications
PSP Game Players, NDS Game Players
Notebook
Ordering Number
SY6981QDC
Package type
QFN3×3-16
Note
Typical Applications
C
BST
BST BD
L
INPUT
LX
Main
FET
SY6981
SVIN
D
IND
Csvin
Battery Charge
Control &
Protection Logic
C
BD
Sync
FET
Block
FET
Charge
Pump
BAT
C
OUT
R
NOR
Li-Ion
Battery
R
NTC
NTC
ICHG
TIM
EN
C
TIM
R
ICHG
C
ICHG
STAT
CV2
CV1
SGND/
PGND
VSEN
SVIN
R
up
Low/Floating High/Low
R
down
Figure1. Schematic Diagram
AN_SY6981
Rev. 0.9
Silergy Corp. Confidential- Prepared for Customer Use Only
1
AN_SY6981
Pinout (top view)
STAT
1
CV2
2
TIM
3
NTC
4
CV1
5
VSEN
6
SVIN
16
7
EN
PGND
15
8
SGND
LX
14
9
ICHG
BD
13
10
BD
BAT
12
11
BST
(
QFN3×3-16
)
Name
STAT
CV2
Top Mark:
cRxyz, (Device
code: cR,
x=year code, y=week code, z= lot number code)
Pin Number
Description
Charge status indication pin. It is open-drain output pin and pulled high to SVIN through
1
a LED to indicate the charge in process. When the charge is done, the LED will be off.
Battery CV voltage selection pin. Program 4 different CV thresholds by setting different
2
voltage on this pin and pin5. Floating or grounding this pin in the application. CV2 pin
can’t be pulled high to any bias voltage higher than 3.3V.
Charge time limit pin. Connect this pin with a capacitor to ground. Internal current source
3
charge the capacitor for TC mode and CC mode’s charge time limit. TC charge time limit
is about 1/9 of CC charge time.
Thermal protection pin. UTP threshold is typical 76% of V
SVIN
and OTP threshold is
4
typical 30.5% of V
SVIN
. Pull up to SVIN can disable charge logic and make the IC operate
as a normal Boost regulator. Pull down to ground can shut down the IC.
Battery CV voltage selection pin. Program 4 different CV thresholds by setting different
5
voltage on this pin and pin2. The detailed information is shown in description section.
Voltage sense of SVIN. If the voltage drops to internal 1.195V reference voltage, the
6
SVIN will be clamped to setting value and input current will be limited.
7
Enable control pin. High logic for enable on, and low logic for enable off.
8
Signal ground pin.
Charge current program pin. Pull down to GND with a resistor R
ICHG.
The mirror current
about 1/10000 of the blocking FET current will dump into the external RC network
9
through ICHG pin and compared to the internal reverence 1V.
So I
CC
= (1V/ R
ICHG
) ×10000, I
TC
= (1V/ R
ICHG
)×1000+0.02.
Connect it to the drain of internal blocking FET. Bypass at least a 4.7µF ceramic cap to
10, 13
GND.
Boost-strap pin. Supply rectified FET’s gate driver. Decouple this pin to LX with a 0.1µF
11
ceramic cap.
12
Battery positive pin.
14
Switch node pin. Connect it to the external inductor.
15
Power ground pin.
Analog power input pin. Connect a MLCC from this pin to ground to decouple high
16
harmonic noise. This pin has OVP and UVLO function to make the charger operate
within safe input voltage range.
TIM
NTC
CV1
VSEN
EN
SGND
ICHG
BD
BST
BAT
LX
PGND
SVIN
AN_SY6981
Rev. 0.9
Silergy Corp. Confidential- Prepared for Customer Use Only
2
AN_SY6981
Absolute Maximum Ratings
(Note1)
STAT, NTC, CV1, VSEN, EN, ICHG, BD, BAT, LX, SVIN ------------------------------------------------------------ 18V
CV2, TIM, BST-LX -------------------------------------------------------------------------------------------------------------- 4V
LX Pin Continuous Current ------------------------------------------------------------------------------------------------------ 5A
Power Dissipation, P
D
@ T
A
= 25°C, QFN3×3 ---------------------------------------------------------------------------- 2.6W
Package Thermal Resistance (Note2)
θ
JA
------------------------------------------------------------------------------------------------------------------- 38°C/W
θ
JC
--------------------------------------------------------------------------------------------------------------------- 4°C/W
Junction Temperature Range ------------------------------------------------------------------------------------ -40°C to 125°C
Lead Temperature (Soldering, 10 sec.) ----------------------------------------------------------------------------------- 260°C
Storage Temperature Range ------------------------------------------------------------------------------------- -65°C to 125°C
Recommended Operating Conditions
(Note3)
SVIN -------------------------------------------------------------------------------------------------------------------- 3.6V to 5.5V
STAT, NTC, CV1, VSEN, EN, ICHG, BD, BAT, LX, -------------------------------------------------------- -0.3V to 16V
CV2, TIM, BST-LX ------------------------------------------------------------------------------------------------ -0.3V to 3.3V
LX Pin Continuous Current ---------------------------------------------------------------------------------------------------- 5A
Junction Temperature Range ------------------------------------------------------------------------------------ -40°C to 125°C
Ambient Temperature Range ------------------------------------------------------------------------------------ -40°C to 85°C
AN_SY6981
Rev. 0.9
Silergy Corp. Confidential- Prepared for Customer Use Only
3
AN_SY6981
Electrical Characteristics
T
A
=25°C, V
IN
=5V, GND=0V, C
IN
=4.7µF, L=0.68µH, R
ICHG
=10kΩ, C
TIM
=470nF, unless otherwise specified.
Parameter
Bias Supply (V
SVIN
)
Supply Voltage
V
SVIN
Under Voltage Lockout
Threshold
V
SVIN
Under Voltage Lockout
Hysteresis
Input Over Voltage Protection
Input Over Voltage Protection
Hysteresis
Quiescent Current
Battery Discharge Current
Input Quiescent Current
Oscillator and PWM
Switching Frequency
Main N-FET Minimum Off Time
Main N-FET Maximum Off Time
Main N-FET Minimum On Time
Power MOSFET
R
DS(ON)
of Main N-FET
R
DS(ON)
of Rectified N-FET
R
DS(ON)
of Blocking N-FET
Voltage Regulation
V
CV1
>1.5V, V
CV2
is
floating
V
CV1
<0.4V, V
CV2
is
floating
V
CV1
>1.5V, V
CV2
<0.4V
V
CV1
<0.4V, V
CV2
<0.4V
8.159
8.358
8.656
8.756
1.5
0.4
100
Rising edge threshold
5.4
200
5.6
300
5.8
8.2
8.4
8.7
8.8
8.241
8.442
8.743
8.844
V
V
mV
V
V
R
NFET_M
R
NFET_R
R
NFET_B
100
50
50
mΩ
mΩ
mΩ
Symbol
V
SVIN
V
UVLO
∆V
UVLO
V
OVP
∆V
OVP
V
SVIN
rising and
measured from V
SVIN
to
GND
Measured from V
SVIN
to GND
V
SVIN
rising and
measured from V
SVIN
to
GND
Measured from V
SVIN
to GND
Shut down IC,
EN=NTC=0
Disable charge,
EN=1,NTC=0
1000
With 18V rating
With 18V rating
With 18V rating
100
30
100
Conditions
Min
3.6
Typ
Max
16
3.6
100
5.8
0.5
Unit
V
V
mV
V
V
I
BAT
I
IN
f
SW
t
MIN_OFF
t
MAX_OFF
t
MIN_ON
10
1.5
µA
mA
kHz
ns
µs
ns
Battery Charge Voltage
V
BAT_REG
High Level Logic for CV1
Low Level Logic for CV1,CV2
Recharge Threshold
Refer to V
BAT_REG
Trickle Current Charge Mode
Battery Voltage Threshold
V
CV_H
V
CV_L
∆V
RCH
V
TRK
AN_SY6981
Rev. 0.9
Silergy Corp. Confidential- Prepared for Customer Use Only
4
AN_SY6981
Battery Connect Detection
NTC Voltage Threshold for
V
DET
Battery Detect
NTC Falling Edge
Detect Delay Time
t
DET
Charge Current
Internal Charge Current Accuracy
I
CC
=1000mA
for Constant Current Mode
Internal Charge Current Accuracy
I
TC
=120mA
for Trickle Current Mode
Termination Current
I
TERM
I
CC
=1000mA
Output Voltage OVP
Output Voltage OVP Threshold
V
OVP
Input Voltage Threshold for Adaptive Current Limit
Voltage Reference of VSEN
V
SEN
Timer
Trickle Current Charge Timeout
t
TC
C
TIM
=330nF
Constant Current Charge Timeout t
CC
Charge Mode Change Delay Time t
MC
Termination Delay Time
t
TERM
Recharge Time Delay
t
RCHG
Short Circuit Protection
Output Short Protection Threshold V
SHORT
Linear Charger Mode
Battery Charger Current When the
I
SC
V
BAT
<V
SHORT
Blocking FET is in Linear Mode
BD Voltage Regulation
V
BD
V
SHORT
<V
BAT
< V
TRK
Enable ON/OFF Control
High Level Logic for Enable
V
EN_H
Control
Low Level Logic for Enable
V
EN_L
Control
Battery Thermal Protection NTC
Under Temperature Protection
Under Temperature Protection
Hysteresis
Over Temperature Protection
V
NTC_UTP
V
NTC_UTP_HYS
V
NTC_OTP
Rising edge
Falling edge
29.5%
85%
30
-10
-50
50
105%
1.17
0.4
3.8
100
110%
1.195
0.5
4.5
30
30
30
2.00
10%
6
6.2
10
50
150
115%
1.22
0.65
5.82
95%
V
SVIN
ms
%
%
mA
V
BAT_REG
V
hour
hour
ms
ms
ms
V
I
CC
V
V
0.4
V
1.70
4%
5.8
1.5
2.30
75%
76%
6%
77%
V
SVIN
30.5%
2%
31.5%
Over Temperature Protection
V
NTC_OTP_HYS
Hysteresis
Thermal Fold-back and Thermal Shutdown
Thermal Fold-back Threshold
T
Fold
Thermal Fold-back Threshold
T
Fold_HYS
Hysteresis
Thermal Fold-back Ratio
Thermal Shutdown Temperature
T
SD
Thermal Shutdown Temperature
T
SD_HYS
Hysteresis
Rising edge
120
20
ºC
ºC
I
CC
ºC
ºC
Rising edge
0.25
160
30
Note 1:
Stresses beyond the “Absolute Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only. Functional operation of the device at these or any other conditions beyond those indicated in the
AN_SY6981
Rev. 0.9
Silergy Corp. Confidential- Prepared for Customer Use Only
5
微控制器 MCU
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
