SGM41526/SGM41527
1.6MHz Synchronous Li-Ion and Li-Polymer
Stand-Alone Battery Chargers
with Automatic Power Path Selector
FEATURES
● High Accuracy
±0.4% Charge Voltage Regulation
● 4A Synchronous 1.6MHz PWM Charger
±5% Charge Current Regulation
Cycle-by-Cycle Current Limit
±4% Input Current Regulation
Integrated 24V Switching MOSFETs
● Safety
Integrated Bootstrap Diode
Thermal Regulation (Current Limit for TJ = +120℃)
Digital Soft-Start
Thermal Shutdown
● Up to 95.2% Charge Efficiency
Battery Thermistor Sense Hot/Cold Charge Suspend
● 30V Absolute Maximum Input Voltage Rating with
Input Under-Voltage Lockout (UVLO)
Adjustable Over-Voltage Threshold
Input Over-Voltage (ACOV) Protection
● 4.5V to 22V Input Operating Voltage Range
APPLICATIONS
● Automatic Power Path Selector (Battery/Adapter)
● Dynamic Power Management (DPM)
● Battery Charge Voltage
Tablet PCs
SGM41526: Select 2-, 3-, or 4-Cell with 4.2V/Cell
Portable Terminals and Printers
SGM41527: Adjustable Charge Voltage
Portable Medical Equipment
● 18μA Battery Current (No Adapter)
Battery Backup Systems
● 1.3mA Input Current (Charge Disabled)
TYPICAL APPLICATION
12V
Adapter
Input
IIN
VIN
Q1
RIN
2Ω
CIN
2.2μF
RAC
10mΩ
Q2
C11
0.1μF
R12
4.02kΩ
VBAT
D2
SGM41526
R1 10Ω
AVCC
C1
1μF
VREF
R2
232kΩ
ACSET
R5
22.1kΩ
Floating
R10
1.5kΩ
D3
CELL
Thermal
STAT Pad
(AGND)
RSR
10mΩ
C5
0.047μF
C8
0.1μF
BTST
PGND
ISET
R3
32.4kΩ
C2
1μF
L
3.3μH
D4
REGN
VREF
R4
100kΩ
Q3
SW
OVPSET
R7
100kΩ
System
R14 1kΩ
ACDRV
R6 1MΩ
IOUT
C4
10μF
C12
0.1μF
ACN PVCC
ACP
CMSRC
nBATDRV
R11
4.02kΩ
D1
VSYS
TTC
C9
10μF
C10
10μF
IBAT
C6
1μF
C7
0.1μF
SRP
SRN
TS
VBAT
VREF
RT
103AT
R8
5.23kΩ
C3
0.1μF
R9
30.1kΩ
Figure 1. SGM41526 Typical Application Circuit (with a 2-Cell Battery)
SG Micro Corp
www.sg-micro.com
JULY 2022 – REV. A
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
GENERAL DESCRIPTION
The SGM41526 and SGM41527 are stand-alone Li-Ion and
The SGM41526 and SGM41527 use dynamic power
Li-polymer battery chargers. The PWM switches are integrated
management (DPM) to prevent overload of the input source
inside and they can automatically select the power path. They
(AC adaptor). With DPM, the output charge current is reduced
also include gate drivers for external power path selector
if the input power limit is reached. The input current is sensed
MOSFETs. The synchronous PWM controller runs at a fixed
and controlled by a precision current-sense amplifier to limit the
frequency (1.6MHz) and is capable of providing accurate
input power.
regulation of charge voltage, charge current and input current.
They are capable of providing continuous battery pack
temperature monitoring in which the charge is only allowed
when the temperature is within the desired range. The
SGM41526 can charge 2-, 3- or 4-cell (selected by CELL pin);
while the SGM41527 has an adjustable charge voltage for up
to 4 cells. In the SGM41527, the FB pin is used for charge
voltage regulation (feedback) using an internal 2.1V reference
and comparator.
Typically, a full battery charging cycle has three consequent
phases: pre-conditioning, constant current and constant
voltage. The charge current is small during the pre-conditioning
phase in which battery is heavily depleted. When the battery
voltage exceeds a threshold voltage, the charge current
increases to its maximum (fast charge current) until the battery
voltage reaches its regulation level. Then the voltage is
regulated and charge current drops. The starting phase is
determined by the initial battery voltage. In constant voltage
condition, the charge current drops automatically. When it
decreases below 10% of the fast charge value, charging is
Gate driver outputs are provided for power path selection that
can be achieved by three external switches. Two N-type
back-to-back MOSFETs (Q1, Q2) are used as input pair
(adapter power in and reverse blocking control) along with a
P-type (Q3) that is used to control the battery connection to the
system bus. The system is powered from adapter by Q1 and
Q2 on if a qualified adapter is present. Otherwise, the system is
connected to the battery by Q3. And with power path control,
the battery cannot feed back to the input.
The SGM41526 and SGM41527 can charge the battery from a
DC source with a voltage up to 22V. This range covers
common adapter voltages and the car battery voltage. The
qualified adapter range is adjustable by OVPSET pin. If the
input voltage is out of the range, Q1 and Q2 will not be turned
on.
For 1-cell applications (only applicable to SGM41527), when
the battery is not removable, the design can be simplified by
direct connection of the battery to the system. Therefore, when
the input source is overloaded, the battery can help power the
terminated. A programmable safety charge timer is provided to
system automatically.
prevent prolonged charging if it is not naturally terminated for
The SGM41526 and SGM41527 are available in a Green
any reason. When the battery voltage falls below recharge
threshold, charge cycle is automatically started (or restarted).
TQFN-5.5×3.5-24L package. It can operate over an ambient
temperature range of -40℃ to +85℃.
If the input voltage falls below the battery voltage, the device
enters sleep mode. In sleep mode, the quiescent current is
very low.
SG Micro Corp
www.sg-micro.com
JULY 2022
2
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
PACKAGE/ORDERING INFORMATION
MODEL
PACKAGE
DESCRIPTION
SPECIFIED
TEMPERATURE
RANGE
ORDERING
NUMBER
PACKAGE
MARKING
PACKING
OPTION
SGM41526
TQFN-5.5×3.5-24L
-40℃ to +85℃
SGM41526YTQQ24G/TR
SGM41526
YTQQ
XXXXX
Tape and Reel, 3000
SGM41527
TQFN-5.5×3.5-24L
-40℃ to +85℃
SGM41527YTQQ24G/TR
SGM41527
YTQQ
XXXXX
Tape and Reel, 3000
MARKING INFORMATION
NOTE: XXXXX = Date Code, Trace Code and Vendor Code.
XXXXX
Vendor Code
Trace Code
Date Code - Year
Green (RoHS & HSF): SG Micro Corp defines "Green" to mean Pb-Free (RoHS compatible) and free of halogen substances. If
you have additional comments or questions, please contact your SGMICRO representative directly.
ABSOLUTE MAXIMUM RATINGS
AGND Referenced Voltages
PVCC ............................................................... -0.3V to 24V
AVCC, ACP, ACN, ACDRV, CMSRC, STAT ...... -0.3V to 30V
BTST ................................................................ -0.3V to 30V
nBATDRV, SRP, SRN ...................................... -0.3V to 24V
SW ...................................................................... -2V to 24V
FB (SGM41527) ............................................... -0.3V to 24V
CELL (SGM41526), OVPSET, REGN, TS, TTC
........................................................................... -0.3V to 7V
VREF, ISET, ACSET ....................................... -0.3V to 3.6V
PGND.............................................................. -0.3V to 0.3V
Differential Voltages
SRP-SRN, ACP-ACN ........................................ -0.5V to 0.5V
Package Thermal Resistance
TQFN-5.5×3.5-24L, θJA ........................................... 37.4℃/W
Junction Temperature .................................................+150℃
Storage Temperature Range ....................... -65℃ to +150℃
Lead Temperature (Soldering, 10s) ............................+260℃
ESD Susceptibility
HBM ............................................................................. 2000V
CDM ............................................................................ 1000V
OVERSTRESS CAUTION
Stresses beyond those listed in Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to
absolute maximum rating conditions for extended periods
may affect reliability. Functional operation of the device at any
conditions beyond those indicated in the Recommended
Operating Conditions section is not implied.
ESD SENSITIVITY CAUTION
This integrated circuit can be damaged if ESD protections are
not considered carefully. SGMICRO recommends that all
integrated circuits be handled with appropriate precautions.
Failure to observe proper handling and installation procedures
can cause damage. ESD damage can range from subtle
performance degradation to complete device failure. Precision
integrated circuits may be more susceptible to damage
because even small parametric changes could cause the
device not to meet the published specifications.
DISCLAIMER
SG Micro Corp reserves the right to make any change in
circuit design, or specifications without prior notice.
RECOMMENDED OPERATING CONDITIONS
Input Voltage Range, VIN......................................4.5V to 22V
Output Voltage, VBAT ............................................. 18V (MAX)
Output Current Range (RSR = 10mΩ), IOUT............. 0.6A to 4A
Maximum Differential Voltage
SRP-SRN, ACP-ACN ................................ -200mV to 200mV
Operating Temperature Range ...................... -40℃ to +85℃
SG Micro Corp
www.sg-micro.com
JULY 2022
3
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
PIN CONFIGURATION
(TOP VIEW)
SW
SW
1
24
PVCC
2
23
PGND
PVCC
3
22
PGND
AVCC
4
21
BTST
ACN
5
20
REGN
ACP
6
19
nBATDRV
CMSRC
7
18
OVPSET
ACDRV
8
17
ACSET
STAT
9
16
SRP
TS
10
15
SRN
TTC
11
14
CELL/FB
AGND
EP
12
13
VREF
ISET
TQFN-5.5×3.5-24L
PIN DESCRIPTION
PIN
NAME
TYPE
FUNCTION
1, 24
SW
P
Switching Node. Connect SW pin to the output inductor and also to a bootstrap capacitor from BTST pin.
2, 3
PVCC
P
Charger Input Voltage. Decouple with at least 10μF ceramic capacitor from PVCC pin to PGND as close
to IC as possible.
4
AVCC
P
IC Supply Power. Place an RC filter (10Ω-1μF) with ceramic capacitor from input power to AVCC pin to
AGND and place capacitor close to the IC. For 5V input, a minimum 5Ω resistor is recommended. The
device under-voltage lockout (UVLO) is sensed on AVCC pin (typically 3.3V rising with 0.21V hysteresis).
5
ACN
I
Input Current Sense Resistor Negative Input. Connect a 100nF ceramic capacitor from ACN to ACP for
differential-mode filtering. Connect a 100nF ceramic capacitor from ACN to AGND for common-mode
filtering.
6
ACP
I/P
Input Current Sense Resistor Positive Input. Connect a 100nF ceramic capacitor from ACN to ACP for
differential-mode filtering. Connect an optional 100nF ceramic capacitor from ACP to AGND for
common-mode filtering.
7
CMSRC
O
Common Source of the ACFET and RBFET. Connect with a 4.02kΩ resistor to the common source of the
input MOSFET ACFET (Q1) and RBFET (Q2) to control the turn-on speed and limit inrush current. An
external minimum 500kΩ resistor between ACDRV pin and CMSRC pin is essential.
O
Gate Driver Output for Input Switches. A 4.02kΩ resistor is placed to the common gate of the external
N-channel ACFET and RBFET power MOSFETs. Connect both FETs as common source. It has
break-before-make logic with respect to the nBATDRV and acts asymmetrical, allowing quick turn-off and
slow turn-on.
O
Open-Drain Charge Status Output Pin with 10kΩ External Pull-Up to the Power Rail. It can be connected
to LED to show the charging status or it can directly communicate with the host. The STAT pin acts as
follows:
During charge: low (LED ON).
Charge completed, charger in sleep mode or charge disabled: high (LED OFF).
Charge suspend (in response to a fault): 0.5Hz, including battery detection, charge suspend, input
over-voltage, battery over-voltage, and timer fault. (LED BLINKS).
8
9
ACDRV
STAT
SG Micro Corp
www.sg-micro.com
JULY 2022
4
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
PIN DESCRIPTION (continued)
PIN
NAME
TYPE
10
TS
I
11
TTC
I
12
VREF
P
3.3V Voltage Reference Output Internally Powered from AVCC Pin. Connect a 1μF ceramic capacitor to
AGND as close to IC as possible. It is usually connected to the resistor divider of ISET, ACSET and TS
pins. It can also be connected to STAT and CELL pins as pull-up rail.
I
Program Pin for Charge Current Settings. The voltage on this pin and the charge shunt resistor RSR
determine the fast charge current. VISET voltage can be set by a resistor divider (VREF-ISET-AGND).
VISET
ICHG =
20 × RSR
The pre-charge and termination currents are equal and determined by ICHG as a ratio of 10%.
The charger disables when ISET voltage is pulled below 30mV and enables if it exceeds 120mV.
13
ISET
FB
(SGM41527)
Temperature Sense Voltage Input. Connect to a negative temperature coefficient (NTC) thermistor that
can sense the battery temperature. The actual hot and cold temperature can be set by a resistor divider
from VREF to TS to AGND. It is recommended to use a 103AT type thermistor for battery pack
temperature sensing.
Safety Timer (Fast Charge) and Termination Control. Pre-charge timer is fixed inside the device (30min
typically). Fast charge safety timer is determined by the capacitor from this pin to AGND (5.6min/nF).
Safety timer is disabled by pulling this pin low or high, but charge termination is disabled only when it is
pulled low.
Cell Selection Pin for SGM41526. Set it low for 4-cell battery, floating for 2-cell, and set it high for 3-cell
battery. Cell voltage regulation is fixed at 4.2V per cell.
CELL
(SGM41526)
14
FUNCTION
I
Feedback Pin for Regulating the Charge Voltage in SGM41527 in the Constant-Voltage Mode. A resistor
divider from battery terminal (VBAT) to FB (VFB) to AGND sets the charge voltage. And the internal
voltage reference is 2.1V.
15
SRN
I
Charge Current Sense Resistor, Negative Input. A shunt resistor is connected between SRN pin and
SRP pin to sense charge current. Connect a 100nF ceramic capacitor between SRN pin and SRP pin
for differential-mode filtering. Connect an optional 100nF capacitor between SRN and AGND for
common-mode filtering.
16
SRP
I/P
Charge Current Sense Resistor, Positive Input. Connect a 100nF ceramic capacitor between SRN pin
and SRP pin for differential-mode filtering. Connect another 100nF ceramic capacitor between SRP pin
and AGND for common-mode filtering.
I
Program Pin to Set Input Current Limit for Dynamic Power Management. A voltage divider from VREF to
ACSET to AGND can be used to set this parameter along with the input shunt resistor RAC:
V
IDPM = ACSET
20 × R AC
I
Program Pin for Input Over-Voltage Detection. The input voltage can be sensed by a resistor voltage
divider from input to OVPSET to AGND so that the ACOV and ACUV can be realized by setting proper
resistor. An input over-voltage (ACOV) is detected if OVPSET voltage exceeds the internal 1.6V
reference. A voltage below 0.494V indicates an input under-voltage (ACUV). If either of the two cases
happens, both of the ACFET and RBFET will be turned off. If it is in charging process, the charge will
terminate. Then the LED that is connected to STAT pin will blink at 0.5Hz to indicate a fault.
17
18
ACSET
OVPSET
19
nBATDRV
O
Gate Driver Output for External P-Type Power MOSFET (Battery Discharge Path). Use a 1kΩ resistor to
connect this pin to the gate of the BATFET (Q3) to control the turn-on speed. The source of the BATFET
connects to the system and the drain connects to the battery positive terminal. In order to decrease
inrush current, the internal gate driver is designed with quick turn-off and slow turn-on functions.
This gate driver has break-before-make logic with respect to the ACDRV gate driver (input switch).
20
REGN
P
5V Internal Supply for the PWM Low-side Switch Driver. Decouple with a 1μF ceramic capacitor from
REGN pin to PGND pin close to the IC. Anode of integrated bootstrap diode is connected to this pin.
21
BTST
P
High-side Power MOSFET Driver Power Supply. Connect a 47nF bootstrap capacitor from SW to BTST.
22, 23
PGND
P
Device Power Ground. On the PCB layout, connect this pin directly to ground points of the input and
output capacitors of the charger. PGND connects to AGND only through in one point on thermal pad
under the IC.
EP
AGND
P
Exposed Pad Beneath the IC. Always solder thermal pad to the board. Use vias to transfer heat to the
back side and other layers of PCB. Thermal pad acts as AGND and only connects to PGND at one
single point.
NOTE:
1. I = Input, O = Output, P = Power.
SG Micro Corp
www.sg-micro.com
JULY 2022
5
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
ELECTRICAL CHARACTERISTICS
(TJ = -40℃ to +85℃, 4.5V ≤ VPVCC, VAVCC ≤ 22V (referred to AGND), typical values at TJ = +25℃, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
22
V
µA
Operating Conditions
AVCC Input Voltage Operating Range
during Charging
VAVCC_OP
4.5
Quiescent Currents
Battery Discharge Current
(Sum of Currents into AVCC, PVCC,
ACP, ACN)
Adapter Supply Current
(Sum of Currents into AVCC, ACP, ACN)
IBAT
IAC
VAVCC > VUVLO, VSRN > VAVCC (Sleep),
TJ = 0℃ to +85℃
7.4
BTST, SW, SRP, SRN, VAVCC > VUVLO, VAVCC > VSRN,
VISET < 30mV, VBAT = 12.6V, charge disabled
18
30
BTST, SW, SRP, SRN, VAVCC > VUVLO, VAVCC > VSRN,
VISET > 120mV, VBAT = 12.6V, charge done
18
30
VAVCC > VUVLO, VAVCC > VSRN, VISET < 30mV,
VBAT = 12.6V, charge disabled
1.3
2.0
VAVCC > VUVLO, VAVCC > VSRN, VISET > 120mV,
charge enabled, no switching
1.4
2.0
VAVCC > VUVLO, VAVCC > VSRN, VISET > 120mV,
charge enabled, switching
15
mA
(1)
Charge Voltage Regulation
CELL floating, 2-cell, measured on SRN
8.4
SRN Regulation Voltage (SGM41526)
VBAT_REG
CELL to VREF, 3-cell, measured on SRN
12.6
CELL to AGND, 4-cell, measured on SRN
16.8
SRN Regulation Voltage (SGM41527)
VFB_REG
Measure on FB
2.1
Charge Voltage Regulation Initial Accuracy
V
V
-0.4
0.4
%
0.12
0.8
V
Current Regulation - Fast Charge
ISET Voltage Range
VISET
RSENSE = 10mΩ
Charge Current Set Factor (Amps of
Charge Current per Volt on ISET Pin)
KISET
RSENSE = 10mΩ
Charge Current Regulation Initial Accuracy
(with Schottky Diode on SW)
5
A/V
VSRP-SRN = 40mV
39.0
41.0
43.1
VSRP-SRN = 20mV
19.1
20.7
22.4
VSRP-SRN = 5mV
3.8
5.4
7.1
30
Charge Disable Threshold
VISET_CD
VISET falling
Charge Enable Threshold
VISET_CE
VISET rising
Leakage Current into ISET
IISET
VISET = 2V
KDPM
RSENSE = 10mΩ
50
100
mV
mV
120
mV
100
nA
Input Current Regulation
Input DPM Current Set Factor (Amps of
Input Current per Voltage on ACSET)
Input DPM Current Regulation Initial
Accuracy (with Schottky Diode on SW)
Leakage Current into ACSET Pin
SG Micro Corp
www.sg-micro.com
IACSET
5
A/V
VACP-ACN = 80mV
78.3
81.6
84.8
VACP-ACN = 40mV
37.3
41.0
44.7
VACP-ACN = 20mV
17.6
20.7
23.8
VACP-ACN = 5mV
4.2
5.5
6.9
VACP-ACN = 2.5mV
1.5
3.0
4.5
VACSET = 2V
100
mV
nA
JULY 2022
6
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
ELECTRICAL CHARACTERISTICS (continued)
(TJ = -40℃ to +85℃, 4.5V ≤ VPVCC, VAVCC ≤ 22V (referred to AGND), typical values at TJ = +25℃, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Current Regulation - Pre-Charge
Pre-Charge Current Set Factor
KIPRECHG
Pre-Charge Current Regulation Initial Accuracy
Percentage of fast charge current
10
(2)
%
VSRP-SRN = 4mV
3.4
4.6
5.7
VSRP-SRN = 2mV
1.3
2.5
3.8
mV
Charge Termination
Termination Current Set Factor
KTERM
Termination Current Regulation Initial Accuracy
Deglitch Time for Termination (Both Edges)
Termination Qualification Time
Termination Qualification Current
Percentage of fast charge current
10
(2)
%
VSRP-SRN = 4mV
2.9
3.9
4.8
VSRP-SRN = 2mV
0.9
1.8
2.7
tTERM_DEG
tQUAL
VSRN > VRECH and ICHG < ITERM
IQUAL
Discharge current once termination is
detected
mV
100
ms
250
ms
2
mA
Input Under-Voltage Lockout Comparator (UVLO)
AC Under-Voltage Rising Threshold
AC Under-Voltage Hysteresis, Falling
VUVLO
Measure on AVCC
2.9
3.3
3.8
V
VUVLO_HYS
Measure on AVCC
210
VSLEEP
VAVCC - VSRN falling
90
VSLEEP_HYS
VAVCC - VSRN rising
210
mV
tSLEEP_FALL_CD
VAVCC - VSRN falling
1
ms
tSLEEP_FALL_FETOFF VAVCC - VSRN falling
5
ms
mV
Sleep Comparator (Reverse Discharging Protection)
Sleep Mode Threshold
Sleep Mode Hysteresis
Sleep Deglitch to Disable Charge
Sleep Deglitch to Turn Off Input FETs
Deglitch to Enter Sleep Mode, Disable VREF
and Enter Low Quiescent Mode
Deglitch to Exit SLEEP Mode, and Enable
VREF
280
mV
tSLEEP_FALL
VAVCC - VSRN falling
100
ms
tSLEEP_PWRUP
VAVCC - VSRN rising
30
ms
ACN-SRN Comparator
Threshold to Turn On BATFET
VACN-SRN
VACN-SRN falling
180
Hysteresis to Turn Off BATFET
VACN-SRN_HYS
VACN-SRN rising
110
mV
Deglitch to Turn On BATFET
tBATFETOFF_DEG VACN-SRN falling
2
ms
Deglitch to Turn Off BATFET
tBATFETON_DEG
50
µs
VACN-SRN rising
400
mV
Battery LOWV Comparator
Pre-Charge to Fast Charge Transition
Fast Charge to Pre-Charge Hysteresis
VLOWV
VLOWV_HYS
CELL floating, 2-cell
Measure on SRN
CELL to VREF, 3-cell
(SGM41526)
CELL to AGND, 4-cell
5.7
5.8
8.4
8.7
9.1
11.1
11.7
12.2
Measure on FB (SGM41527)
1.42
1.46
1.50
CELL floating, 2-cell
Measure on SRN
CELL to VREF, 3-cell
(SGM41526)
CELL to AGND, 4-cell
800
6.1
V
400
600
mV
Measure on FB (SGM41527)
100
VLOWV Rising Deglitch
tPRE2FAS
Delay to start fast charge current
25
ms
VLOWV Falling Deglitch
tFAST2PRE
Delay to start pre-charge current
25
ms
SG Micro Corp
www.sg-micro.com
JULY 2022
7
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
ELECTRICAL CHARACTERISTICS (continued)
(TJ = -40℃ to +85℃, 4.5V ≤ VPVCC, VAVCC ≤ 22V (referred to AGND), typical values at TJ = +25℃, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
CELL floating, 2-cell
110
200
290
CELL to VREF, 3-cell
190
300
430
CELL to AGND, 4-cell
280
400
540
UNITS
Recharge Comparator
Recharge Threshold, below Regulation
Voltage Limit,
VBAT_REG - VSRN (SGM41526),
or VFB_REG - VFB (SGM41527)
VRECHG
Measure on SRN
(SGM41526)
mV
Measure on FB (SGM41527)
70
VRECHG Rising Deglitch
tRECH_RISE_DEG VFB decreasing below VRECHG
10
ms
VRECHG Falling Deglitch
tRECH_FALL_DEG VFB increasing above VRECHG
10
ms
Battery Over-Voltage Comparator
Over-Voltage Rising Threshold
VOV_RISE
As percentage of VBAT_REG (SGM41526)
or VFB_REG (SGM41527)
104
%
Over-Voltage Falling Threshold
VOV_FALL
As percentage of VSRN (SGM41526)
or VFB_REG (SGM41527)
102
%
Input Over-Voltage Comparator (ACOV)
AC Over-Voltage Rising Threshold to
Turn Off ACFET
AC Over-Voltage Falling Hysteresis
AC Over-Voltage Rising Deglitch to
Turn Off ACFET and Disable Charge
AC Over-Voltage Falling Deglitch to
Turn On ACFET
VACOV
OVPSET rising
1.53
1.6
1.69
V
VACOV_HYS
OVPSET falling
40
mV
tACOV_RISE_DEG OVPSET rising
1
µs
tACOV_FALL_DEG OVPSET falling
30
ms
Input Under-Voltage Comparator (ACUV)
AC Under-Voltage Falling Threshold to
Turn Off ACFET
VACUV
OVPSET falling
VACUV_HYS
OVPSET rising
80
mV
tACOV_FALL_DEG OVPSET falling
1
µs
tACOV_RISE_DEG OVPSET rising
30
ms
VISET > 120mV, charging
120
℃
TSHUT
Temperature rising
150
℃
TSHUT_HYS
Temperature falling
20
℃
Thermal Shutdown Rising Deglitch
TSHUT_RISE_DEG Temperature rising
100
µs
Thermal Shutdown Falling Deglitch
TSHUT_FALL_DEG Temperature falling
10
ms
AC Under-Voltage Rising Hysteresis
AC Under-Voltage Falling Deglitch to
Turn Off ACFET and Disable Charge
AC Under-Voltage Rising Deglitch to
Turn On ACFET
0.44
0.494
0.55
V
Thermal Regulation
Junction Temperature Regulation Accuracy
TA_REG
Thermal Shutdown Comparator
Thermal Shutdown Rising Temperature
Thermal Shutdown Hysteresis
Thermistor Comparator
Cold Temperature Threshold, TS Pin
Voltage Rising Threshold
Cold Temperature Hysteresis, TS Pin
Voltage Falling
Hot Temperature TS Pin Voltage Rising
Threshold
Cut-Off Temperature TS Pin Voltage
Falling Threshold
Deglitch Time for Temperature out of
Range Detection
Deglitch Time for Temperature in Valid
Range Detection
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VLTF
Charger suspends charge,
as percentage of VVREF
72.1
73.6
75.2
%
0.68
1.45
%
VLTF_HYS
As percentage of VVREF
VHTF
As percentage of VVREF
45.8
47.3
48.8
%
VTCO
As percentage of VVREF
43.2
44.6
45.7
%
tTS_CHG_SUS
tTS_CHG_RESUME
VTS > VLTF, or VTS < VTCO, or VTS < VHTF
20
ms
VTS < VLTF - VLTF_HYS or VTS > VTCO,
or VTS > VHTF
400
ms
JULY 2022
8
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
ELECTRICAL CHARACTERISTICS (continued)
(TJ = -40℃ to +85℃, 4.5V ≤ VPVCC, VAVCC ≤ 22V (referred to AGND), typical values at TJ = +25℃, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Charge Over-Current Comparator (Cycle-by-Cycle)
Charge Over-Current Rising Threshold,
VSRP > 2.2V
VOCP_CHRG
Current as percentage of fast charge current
180
%
Charge Over-Current Limit Min, VSRP < 2.2V
VOCP_MIN
Measure VSRP-SRN
46
mV
Charge Over-Current Limit Max, VSRP > 2.2V
VOCP_MAX
Measure VSRP-SRN
77
mV
Measure on HSFET
10
A
HSFET Over-Current Comparator (Cycle-by-Cycle)
Current Limit on HSFET
IOCP_HSFET
Charge Under-Current Comparator (Cycle-by-Cycle)
Charge Under-Current Falling Threshold
VUCP
Measure on VSRP-SRN
1
5
12
mV
Battery Short Comparator
Battery Short Falling Threshold
VBATSHT
Measure on SRN
2
V
Battery Short Rising Hysteresis
VBATSHT_HYS
Measure on SRN
200
mV
Deglitch on Both Edges
tBATSHT_DEG
1
µs
Charge Current during BAT_SHORT
VBATSHT
Percentage of fast charge current
10
(2)
%
VREF Regulator
VREF Regulator Voltage
VREF Current Limit
VVREF_REG
IVREF_LIM
VAVCC > VUVLO, no load
3.24
VVREF = 0V, VAVCC > VUVLO
20
VAVCC > 10V, VISET > 120mV
4.8
IREGN_LIM
VREGN = 0V, VAVCC > 10V, VISET > 120mV
20
Pre-Charge Safety Timer
tPRECHRG
Pre-charge time before fault occurs
Fast Charge Timer Range
tFASTCHRG
TCHG = CTTC × KTTC
3.3
3.36
V
80
mA
5.2
V
100
mA
REGN Regulator
REGN Regulator Voltage
REGN Current Limit
VREGN_REG
5.0
TTC Input
Fast Charge Timer Accuracy
Timer Multiplier
TTC Low Threshold
TTC Source/Sink Current
1800
1
10
-10
KTTC
VTTC_LOW
TTC falling
ITTC
45
s
10
hr
%
5.6
min/nF
0.33
V
50
55
µA
TTC Oscillator High Threshold
VTTC_OSC_HI
1.5
V
TTC Oscillator Low Threshold
VTTC_OSC_LO
1.0
V
Battery Switch (BATFET) Driver
BATFET Turn-Off Resistance
RDS_BAT_OFF
VAVCC > 5V
200
Ω
BATFET Turn-On Resistance
RDS_BAT_ON
VAVCC > 5V
10
kΩ
BATFET Drive Voltage
VBATDRV_REG
VBATDRV_REG = VACN - VBATDRV when VAVCC > 5V
and BATFET is on
6.4
V
BATFET Power-Up Delay to Turn Off
BATFET after Adapter is Detected
tBATFET_DEG
5.1
30
ms
160
µA
AC Switch (ACFET) Driver
ACDRV Charge Pump Current Limit
IACFET
Gate Drive Voltage on ACFET
VACDRV_REG
Maximum Load between ACDRV and CMSRC
RACDRV_LOAD
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VACDRV - VCMSRC = 5V
VACDRV - VCMSRC when VAVCC > VUVLO
5.4
20
5.6
V
kΩ
JULY 2022
9
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
ELECTRICAL CHARACTERISTICS (continued)
(TJ = -40℃ to +85℃, 4.5V ≤ VPVCC, VAVCC ≤ 22V (referred to AGND), typical values at TJ = +25℃, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
tDRV_DEAD
Dead time when switching between ACFET
and BATFET
10
µs
tWAKE
Max time charge is enabled
500
ms
Wake Current
IWAKE
RSENSE = 10mΩ
Discharge Timer
tDISCH
Max time discharge current is applied
Discharge Current
Fault Current after a Time-Out Fault
AC/BAT Switch Driver Timing
Driver Dead Time
Battery Detection
Wake Timer
Wake Threshold with Respect to VREG to
Detect Absent during Wake
Discharge Threshold to Detect Battery
Absent during Discharge
100
250
400
mA
1
s
IDISCH
9.5
mA
IFAULT
2
mA
VWAKE
Measure on SRN (SGM41526)
100
mV/cell
VDISCH
Measure on SRN (SGM41526)
2.9
V/cell
1600
kHz
Dead time when switching between LSFET
and HSFET no load
30
ns
VBTST - VSW = 4.5V
29
55
mΩ
33
65
mΩ
Internal PWM
PWM Switching Frequency
Driver Dead Time
fSW
(1)
tSW_DEAD
High-side MOSFET On-Resistance
RDS_HI
Low-side MOSFET On-Resistance
RDS_LO
Bootstrap Refresh Comparator Threshold
Voltage
VBTST_REFRESH
VBTST - VSW when low-side refresh pulse is
requested, VAVCC = 4.5V
2.8
VBTST - VSW when low-side refresh pulse is
requested, VAVCC > 6V
2.8
V
Internal Soft-Start (8 Steps to Regulation Current ICHG)
Soft-Start Steps
Soft-Start Step Time
SS_STEP
8
step
tSS_STEP
1.6
tCE_DELAY
1.5
s
0.85
V
3
ms
Charger Section Power-Up Sequencing
Delay from ISET above 120mV to Start
Charging Battery
Integrated BTST Diode
Forward Bias Voltage
VF
IF = 120mA at +25℃
Reverse Breakdown Voltage
VR
IR = 2μA at +25℃
21
V
Logic IO Pin Characteristics (STAT, CELL)
STAT Output Low Saturation Voltage
CELL Pin Input Low Threshold, 4-Cell
(SGM41526)
CELL Pin Input Mid Threshold, 2-Cell
(SGM41526)
CELL Pin Input High Threshold, 3-Cell
VOUT_LO
Sink current = 5mA
VCELL_LO
CELL pin voltage falling edge
VCELL_MID
CELL pin middle level voltage
VCELL_HI
CELL pin voltage rising edge
0.6
0.3
0.7
V
2.5
2.7
V
V
V
NOTES:
1. Specified by design.
2. The minimum current is 250mA on 10mΩ sense resistor.
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JULY 2022
10
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency vs. Charge Current
100
95
95
90
90
Efficiency (%)
Efficiency (%)
Efficiency vs. Charge Current
100
85
80
75
0
1000
2000
3000
80
75
VIN = 15V, 3 Cells, VBAT = 11.4V
VIN = 15V, 2 Cells, VBAT = 7.6V
70
85
4000
70
Charge Current (mA)
2000
3000
VIN = 15V, 2 Cells, VBAT = 7.6V
VSW
10V/div
2A/div
VACDRV
STAT
ICHG
Time (20ms/div)
Time (5ms/div)
Charge Enable by ISET
Charge Disable by ISET
Time (200ms/div)
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VSW
IL
2A/div
IL
VIN = 15V, 2 Cells, VBAT = 7.6V
10V/div
5V/div 20V/div 2A/div
VREGN
STAT
VISET
500mV/div
VISET
500mV/div
VIN = 15V, 2 Cells, VBAT = 7.6V
4000
5V/div
VVREF
1000
Current Soft-Start
10V/div 2V/div 10V/div
VAVCC
0
Charge Current (mA)
Power-Up
VIN = 15V, 2 Cells, VBAT = 0V, VISET = 0V
VIN = 5V, 1 Cell, VBAT = 3.8V
VIN = 9V, 1 Cell, VBAT = 3.8V
Time (2µs/div)
JULY 2022
11
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Continuous Conduction Mode Switching
Discontinuous Conduction Mode Switching
VIN = 15V, 2 Cells, VBAT = 7.6V, ICHG = 2A
Time (200ns/div)
Time (200ns/div)
BATFET to ACFET Transition During Power-Up
VBATDRV
ISYS
ICHG
Time (10ms/div)
Time (100µs/div)
Battery-to-Ground Short Protection
VSRN
2A/div
10V/div
VSYS
IIN
2A/div
VACDRV
VIN = 20V, 1 Cell, VBAT = 3.8V
2A/div
VAVCC
System Load Transient (Input Current DPM)
10V/div 10V/div 10V/div
VIN = 15V, 2 Cells, VBAT = 0V
1A/div
IL
10V/div
VSW
1A/div
IL
10V/div
VSW
VIN = 15V, 2 Cells, VBAT = 9V, ICHG = 0.15A
Battery-to-Ground Short Transition
VIN = 15V, 3 Cells, VBAT = 11.4V
VSRN
VIN = 15V, 3 Cells, VBAT = 11.4V
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VSW
IL
2A/div
2A/div
Time (2ms/div)
10V/div
10V/div
IL
5V/div
5V/div
VSW
Time (10µs/div)
JULY 2022
12
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Battery Insertion and Removal
5V/div
VSRN
VIN = 15V, 3 Cells, VBAT = 11.4V
10V/div
VSW
1A/div
IL
Time (500ms/div)
SG Micro Corp
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JULY 2022
13
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
FUNCTIONAL BLOCK DIAGRAM
VREF
Thermal PAD
12
AVCC 4
3.3V
VSRN + 90mV
CE
VREF
LDO
+
REGN
LDO
ACN
6
+
20×
Refresh
+
5
20 × IAC
Fast/PreCHRG
Sele ction
LOWV
SRP 16
SRN 15
EA &
PWM Control
IBAT_REG
Driver
+
+
20×
Thermal
Regula tion
SGM415 26
+
OCP
1.36V
2.03V
3
PVCC
1
SW
24
SW
22
PGND
23
PGND
SLE EP
BAT_SHORT
RECHG
10
TS
Timer Fau lt
+
+
+
+
8
ACDRV
7
CMSRC
19
nBA TDRV
10% × V ISET
2V
VREF
Battery
Detection
Charge
Control
Log ic
SUSPE ND
ACUV
VISET
+
20 × ICH G
VSRN
ACOV
1.6V
OTP
UVLO
+
Safety Timer
TTC 11
UCP
Charge
Termination
+
LOWV
STAT
PVCC
BAT_OVP
2.184V
SGM415 27
0.494V
2
2.1V
+
OVP SET 18
BTST
20 × ICH G
SRN
CELL
(SGM415 26)
14
FB
(SGM415 27)
21
+
ACSET 17
ISET 13
REGN
UVLO
SLE EP
ACP
20
+
+
+
CE
120mV
9
VSRN + 180mV
VACN
SGM41526
SGM41527
ACDRV
Charg e Pump
SLE EP
+
ACN-SRN
UVLO
ACOV
System
Power
Selector
Control
ACUV
Figure 2. Functional Block Diagram
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JULY 2022
14
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
DETAILED DESCRIPTION
The SGM41526 and SGM41527 are Li-Ion and Li-polymer
fixed-frequency synchronous PWM battery chargers with
integrated switching power MOSFETs. Using external
switches, power path management is provided along with
accurate regulation of the input current, charge current and
battery voltage. The internal block diagram is given in Figure 2.
Battery Voltage Regulation
An accurate PWM voltage regulator is used for charge
voltage regulation. For the SGM41526, the number of battery
cells depends on the CELL pin. Two (CELL = floating), three
(CELL = VREF) or four (CELL = AGND) cells can be
connected in series with a fixed nominal voltage of 4.2V per
cell. Table 1 shows the charge regulation voltage in each
case.
Table 1. Defining Number of Battery Cells for SGM41526
CELL Pin Voltage
Charge Regulation Voltage
Floating
8.4V (2 Cells)
VREF
12.6V (3 Cells)
AGND
16.8V (4 Cells)
For the SGM41527, the regulation voltage is adjustable. The
FB voltage is compared to an internal 2.1V voltage reference
like a conventional voltage regulator. The regulation voltage
can be adjusted by using an external resistor divider on the
battery voltage (output voltage). Connect the center point of
the resistor divider to the FB pin. The battery regulation
voltage (VBAT) in the SGM41527 is calculated by Equation 1:
R
VBAT= 2.1V × 1 + 1
R
2
(1)
where
• R1 is connected between the battery positive terminal and
FB.
• R2 is connected between FB and AGND.
Battery Current Regulation
The maximum charging current for fast charge is set by the
ISET input. Connect battery current sense resistor (RSR)
between SRP and SRN. The equation for charge current is
given by:
adjustable charge current is 4A, and with a 20mΩ resistor, it is
2A. If VISET = 0.5V and RSR = 10mΩ, the fast charge current is
ICHG = 2.5A.
Pulling the ISET voltage down to ground (below 30mV)
disables the charger. To enable the charger, the ISET voltage
should exceed 120mV. The minimum charge current is limited
by the 120mV threshold level. For example, when RSR =
10mΩ, the minimum fast charge current is no less than 600mA.
As a protective feature, if the device junction temperature
exceeds +120 ℃ , the charge current folds back and is
internally reduced to keep the junction temperature below
+120℃.
Pre-Charge Phase
If the battery voltage is lower than VLOWV when the device is
powered up, the charge will start with a small pre-charge
current to safely recover the battery from deep discharge
state. If the battery voltage still does not exceed the VLOWV
threshold after 30 minutes, charging will stop, and fault status
will be declared by the status pins. VLOWV is typically 2.9V/cell
for SGM41526 and 1.46V on FB pin for SGM41527. The
pre-charge current is determined by the fast charge current
as a ratio of 10%:
IPRECHARGE =
VISET
200 × RSR
(3)
The deglitch time of fast charge and pre-charge transition is
25ms.
Typical Charge Cycle
Figure 3 shows a complete charge cycle profile (battery
voltage and current versus time) with all the three phases
followed by a typical discharge and auto recharge. The
charge is started assuming that the battery is in a deep
discharge state (low battery voltage). After termination and
stopping the charge, the battery is normally discharged by
system loads. When the voltage falls below the recharge
threshold, another cycle is initiated from fast charge, to bring
the battery back to the full charge state. A new charging cycle
begins when any of the following conditions is met:
(2)
• The SRN pin voltage falls below the recharge threshold (VRECH).
• A power-on-reset (POR).
• Disable and enable charge by pulling ISET pin below 30mV
and then above 120mV, respectively.
The maximum of the full-scale SRP-SRN differential voltage
is 40mV, and it determines the maximum charge current
selected by ISET. The maximum valid input voltage of ISET is
0.8V. For example, with a 10mΩ sense resistor, the maximum
Depending on the battery voltage, the charge is started with
the proper phase. Charge sequence details will be explained
in the next sections.
ICHG =
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VISET
20 × RSR
JULY 2022
15
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
DETAILED DESCRIPTION (continued)
VREG
Pre-Charge Current
Regulation Phase
Fast Charge Current
Regulation Phase (CC)
Fast Charge Voltage
Regulation Phase (CV)
Termination
Discharge
Termination
Discharge
Auto Recharge
ICHG
VRECH
Charge
Current
Battery
Voltage
VLOWV
10%ICHG
Pre-Charge
Timer
Fast Charge Safety Timer
Auto Recharge
One Complete Charge Cycle
Figure 3. Typical Charge and Discharge Profile
Regulation of the Input Current
The input current is used to power the system and to charge
the battery. System current may vary from zero to maximum
load. With dynamic power management (DPM) capability, the
adapter does not need to be designed for maximum power
demand for both charge and system at the same time.
Otherwise it will lead to a bulky AC adapter and relatively
higher cost. With DPM, the charge current is reduced when
the system has high demand for power, such that the input
current is regulated to a predefined maximum. Therefore, the
AC adapter can be designed for lower power that results in
smaller adapter size and cost.
Input current regulation level of DPM is programmed by the
voltage on ACSET pin and the input shunt resistor RAC, as
given in Equation 4:
IDPM =
VACSET
20 × R AC
(4)
The sense voltage across RAC (typically 10mΩ) is sent to ACP
and ACN pins. The regulation accuracy can be improved with
larger sense resistor but at the cost of lower efficiency.
Termination, Recharge and Timers
In the constant voltage charging phase, the device also
detects the charging current and battery voltage. The charge
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cycle will be terminated if the battery is fully charged that is
detected when charge voltage exceeds recharge threshold
(VRECH) and charge current falls below termination current
threshold (ITERM). Charge voltage is sensed on the SRN pin of
the SGM41526 and on the FB pin of the SGM41527.
Recharge voltage threshold (VRECH) is a little bit lower than
the regulation voltage and the termination current threshold
(ITERM) is equal to 10% of the programmed fast charge current
as given in Equation 5:
ITERM =
VISET
200 × RSR
(5)
For battery safety, prolonged charging must be avoided, so
time limits are considered for charge phases. For pre-charge
phase, a fixed 30-minute safety timer is employed. For the
fast charge phase, an adjustable timer is used. This timer can
be programmed by a capacitor (CTTC) connected between the
TTC and AGND pins based on Equation 6:
tTTC (min) = CTTC (nF) × KTTC (min/nF)
(6)
where KTTC is a constant typically equal to 5.6min/nF.
Connecting TCC pin to AGND disables both termination and
fast charge timers. Connecting TCC pin to VREF disables the
safety timer only and termination timer remains functioning.
JULY 2022
16
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
DETAILED DESCRIPTION (continued)
Device Power-Up
The device power pin (AVCC) can be supplied by the battery
or the adapter. If AVCC voltage falls below UVLO threshold,
the device remains disabled. If AVCC voltage exceeds UVLO
threshold, the device is enabled and another comparator
(charger sleep comparator) checks the AVCC voltage to
identify the power source. If the adapter is detected and the
AVCC voltage exceeds the SRN voltage (battery voltage), the
charger exits the sleep mode and can be enabled for
charging. If the AVCC voltage is lower than SRN, the charger
enters the low quiescent current sleep mode to minimize
power taken from the battery. In the sleep mode, the STAT pin
goes to high-impedance state and VREF output is turned off.
AVCC Input Under-Voltage Lockout (UVLO)
Usually the system cannot properly operate if AVCC voltage
is too low (under-voltage). Therefore the device is enabled
until AVCC voltage exceeds a minimum level (UVLO). All
circuits on the IC are disabled if AVCC falls below UVLO
threshold, regardless of the source of power.
Input Over-Voltage/Under-Voltage Protection
The SGM41526 and SGM41527 provide over-voltage (OV)
and under-voltage (UV) protections to avoid system damage
due to high or low input supply voltage. The input is qualified
if input voltage is within the UV and OV window. The ACOV
and ACUV comparators monitor the OVPSET voltage. If it
exceeds 1.6V (for OV) or falls below 0.494V (for UV), the
charge will be disabled and both input switches (Q1 and Q2)
will be turned off to disconnect the system from the power
supply. A resistor divider from input source can be used to
define the input qualification window. Unlike UVLO that acts
on AVCC (powered from input supply or battery), the OV and
UV protections act only on the input power supply.
Charge Enable and Disable
If all following conditions are fulfilled, a charge will be started:
• VISET > 120mV (enable charge).
• VAVCC > VUVLO (device not in UVLO).
• VAVCC > VSRN (charger not in sleep mode).
• 0.494V < VOVPSET < 1.6V (qualified power input).
• Not in Thermal Shutdown (TSHUT).
• No TS fault (battery temperature not too hot or cold).
• Detect battery presence.
• ACFET is turned on.
• TTC or pre-charge timers are not expired.
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• REGN and VREF pins are at their normal voltage levels
without overloading.
The device remains charging until the battery is fully charged
(normal termination), unless the charge is disabled when
VISET < 30mV or when any of the above conditions is not
fulfilled during the charge.
Power Path Selection
The SGM41526 and SGM41527 can automatically select the
input adapter or battery as power source for the system. By
default, the system is powered from the battery during device
power-up or in sleep mode. The device can exit sleep mode if
a qualified adapter is plugged in. Then the BATFET is turned
off and the back-to-back MOSFET pair on the power input is
turned on with a protective break-before-make logic so that
system is connected to adaptor. The ACFET turns on after
10μs dead time when BATFET is turned off, so that it avoids
direct input to battery short that can cause over-current
through the selector switches.
Both gates of the back-to-back MOSFET pair on the power
input are driven by the ACDRV pin. The sources are
connected together to the CMSRC pin (Figure 1). The drain of
the RBFET (Q2) is connected to the ACP pin. Q2 is for
reverse discharge protection to avoid current flow from the
battery to the input source. Low RDS(ON) switches are
recommended for Q1 and Q2 to minimize conduction losses
and heat generation. ACFET (Q1) can control the connection
of adapter to system and battery. This switch also limits the
inrush current rise/fall rate (di/dt) when input adapter is
connected to the system by controlling the turn-on time.
The BATFET (P-channel, Q3) controls the connection of
battery and system. Its gate is driven by nBATDRV pin and its
source is connected to system.
The ACFET remains off, as long as a qualified voltage is not
detected, by applying zero gate-source voltage. ACFET
separates the adapter from system.
If the device is not in UVLO and system voltage is at most
0.18V above the battery, the BATFET remains on by applying
-5.9V to the gate-source through the nBATDRV pin (gate
voltage clamps to ground if the system voltage is less than
5.9V). The conditions can be represented as:
• VAVCC > VUVLO (not in UVLO).
• VACN < VSRN + 180mV.
The source pin of the BATFET is connected to the system,
ACN pin and PVCC.
JULY 2022
17
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
DETAILED DESCRIPTION (continued)
If the input voltage is qualified and AVCC voltage is at least
0.21V above SRN (battery), the device can exit the sleep
mode and transfer the system from battery to adapter. With
the break-before-make logic, there is a 10μs dead time
between input MOSFET pair and BATFET. At first the
BATFET is turned off to disconnect battery from system by
pulling up the nBATDRV voltage to ACN pin. Then the ACFET
is turned on with a 5.6V gate drive voltage between the
ACDRV and CMSRC pins, which is provided by an internal
charge pump. The conditions for connecting the adapter to
the system can be represented as follows:
• VACUV < VOVPSET < VACOV.
• VAVCC > VSRN + 210mV.
When any of above conditions is no longer valid, ACFET is
turned off and the device enters the sleep mode. BATFET
remains off until the system voltage falls close to SRN
(battery voltage). Then the BATFET turns on and connects
the battery and system. An internal regulator drives
nBATDRV pin to ACN - 5.9V to turn on BATFET.
Asymmetrical gate driving is used for fast turn-off and slow
turn-on of the ACFET and BATFET. This will allow smooth
transitions and soft connection of the system to the supply
line. Turn-on delay can be increased by adding capacitance
between the gate and source of the switches.
Charge Converter
The charge converter in SGM41526/7 is a 1.6MHz PWM
step-down regulator. The fixed switching frequency makes
the filter design simple under all input/output or temperature
conditions. Pulse skipping occurs if the duty cycle is
approximately 97%. A type III compensation network is
designed inside so that the use of low ESR ceramic
capacitors on the output is allowed. The compensated error
amplifier output is compared with 1.6MHz sawtooth ramp
voltage to generate PWM wave. The sawtooth amplitude is
proportionally adjusted to the AVCC voltage (input
feedforward) to compensate the impact of the input voltage
variations on the loop gain and simplify the loop
compensation.
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Internal Charge Current Soft-Start
The charge current automatically soft starts when fast charge
mode begins to limit the stress on the converter components
due to the current overshoots. During the soft-start, a total of
8 current levels are available for the programmed regulation
current with an evenly spaced step. Each step lasts almost
1.6ms, for a typical soft-tart rise time of 12.8ms. This function
is designed inside the device and no external components are
required.
Charge Over-Current Protection
The high-side MOSFET current in the converter is always
monitored by a sense FET and if it exceeds the MOSFET
current limit (typically 10A), the high-side MOSFET is turned
off until the next cycle.
There is another over-current protection for charge current.
When it exceeds 180% of the programmed value, the
high-side MOSFET is also turned off until the current falls
below the threshold.
Charge Negative Current Protection
When the battery is charged, the inductor current reduces
and may become negative. This negative current means that
the battery feeds energy to input through converter (it is
called Boost effect). The Boost effect can cause over-voltage
on the input circuit and AVCC, which can damage the input
components, device itself and the system. To prevent the
boosting and negative charge current, the low-side switch
should be turned off before the current drops to zero. The
device senses the charge current by the voltage of the
SRP-SRN, and if it falls below 5mV, the low-side switch is
turned off for the rest of the switching cycle. This leads to
discontinuous conduction mode (DCM) operation of the
converter. Keeping low-side switch off limits the charging of
bootstrap capacitor that feeds the high-side switch gate driver.
A comparator always checks the high-side driver supply
voltage, and if it falls below 2.8V the low-side switch is turned
on for a short period to refresh and recharge the bootstrap
capacitor voltage. This protection overrides the negative
charge current protection.
JULY 2022
18
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
DETAILED DESCRIPTION (continued)
Battery Detection
SRN voltage falls below recharge threshold. If the battery
voltage does not fall below the battery LOWV threshold in 1s,
the battery is detected as present so the 9.5mA sink is turned
off and the charge starts. During the 1s period, the 9.5mA
discharge current is disabled as long as the battery voltage
falls below battery LOWV threshold. Then the converter
generates a small charge current to charge the SRN pin. The
charge current is 250mA typically with 10mΩ sense resistor.
Now, if 0.5s timer times out and the battery voltage exceeds
the recharge threshold, the detection is no-battery and the
process will restart from beginning to detect insertion of the
battery. If after the 0.5s period, the voltage does not exceed
the recharge voltage threshold, the battery is detected as
present and the proper charging phase will start.
Battery presence detection is important and specially needed
for the applications with removable batteries. The SGM41526
and SGM41527 use a reliable detection method for battery
absence, battery insertion and battery removal. This detection
procedure runs during power-up or when the battery voltage
is lower than the recharge threshold. A low voltage on SRN
pin (that connects to battery) can be detected due to battery
discharge or battery removal. The detection process is
designed such that the large capacitors on the charger output
are not detected as battery. The detection flow chart is given
in Figure 4.
Battery detection starts by applying a 9.5mA sink current
though the SRN pin to the battery at power-up or when the
POR or Recharge
Apply 9.5mA discharge
current, start 1s timer
VFB < VLhWV
NO
1s timer expired
YES
YES
Disable 9.5mA
discharge current
Battery Present,
Begin Charge
NO
Enable 250mA charge
current, start 0.5s timer
0.5s timer expired
VFB > VRECH
NO
Battery Present,
Begin Charge
YES
Disable 250mA
charge current
Battery Absent
Figure 4. SGM41526 and SGM41527 Battery Detection Flow Chart
Battery
Absent
Battery
Absent
VBAT_REG
VRECH
Battery
Present
VLOWV
Figure 5. Timing of the Battery Insertion Detection
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JULY 2022
19
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
DETAILED DESCRIPTION (continued)
Note that the total output capacitance that appears parallel to
the battery should not be too large such that with the applied
sink or charge currents and timing the no-battery voltage
changes fast and passes the detection thresholds within 1s or
0.5s periods. Equations 7 and 8 can be used to calculate the
maximum output capacitances:
CMAX =
CMAX =
IDISCH × tDISCH
( 4.1V - 2.9V ) × NCell
(for SGM41526)
IDISCH × tDISCH
(for SGM41527)
R
( 2.03V - 1.46V ) × 1 + 1
R2
(7)
(8)
where
CMAX = maximum output capacitance.
IDISCH = discharge current.
tDISCH = discharge time.
NCell = number of cells in the battery.
R1 and R2: FB pin feedback resistors from the battery.
9.5mA × 1s
= 2.8mF
500kΩ
0.57V × 1 +
100kΩ
Battery Short Protection
During charge, if the battery voltage sensed on the SRN pin
falls below 2V threshold, the battery is considered in short
condition. The charge will quickly stop for a 1ms period
followed by a soft-start toward the pre-charge current level to
prevent over-current and saturation of the inductor. In battery
short condition, the charger operates in nonsynchronous
mode.
Battery voltage is continuously monitored for over-voltage
protection. If the sensed voltage exceeds 104% of the
regulation voltage, the converter high-side switch remains off.
This protection reacts in one cycle. The over-voltage may
occur due to a battery disconnection or load removal. The
stored energy in the output capacitors is discharged by
sinking a total of 6mA current through SRP and SRN pins to
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Battery temperature is continuously monitored by measuring
the voltage between the TS pin and AGND that is sensed by a
NTC (negative temperature coefficient) thermistor attached to
the battery pack. A resistor divider from VREF is used to
adjust the temperature limits. The voltage of TS pin is
compared with internal thresholds and charge process will not
begin until the TS pin voltage (which indicates battery
temperature) is within the VLTF to VHTF window. If during
charge the battery get too hot or too cold and temperature
goes out of the allowed range, the charge will suspend by
turning off PWM switches. The charge resumes automatically
if the temperature returns to the allowed window.
VREF
VLTF
VLTFH
(9)
Therefore, the total capacitance on the battery node should
be less than 2800μF.
Battery Over-Voltage Protection
Battery Temperature Qualification
Figure 6 illustrates the temperature qualification function and
the thresholds for the charge initiation, suspension and
recovery.
Example:
For a 3-cell Li+ charger (12.6V battery voltage regulation),
with R1 = 500kΩ, R2 = 100kΩ, IDISCH = 9.5mA and tDISCH = 1s,
the maximum allowed capacitance is:
CMAX =
AGND. The charge will be disabled if the over-voltage
condition is not cleared for more than 30ms.
Temperature Range to
Initiate Charge
Temperature Range during
a Charge Cycle
Charge Suspended
Charge Suspended
Charge at full C
Charge at full C
Charge Suspended
Charge Suspended
VHTF
AGND
VREF
VLTF
VLTFH
VTCO
AGND
Figure 6. Battery Temperature Qualification Function and
Thresholds on the Sensed TS Pin Voltage
The TS pin resistor divider (Figure 7) can be calculated based
on the hot and cold temperature levels recommended for the
battery by Equation 10 and Equation 11:
RT2
1
1
VVREF × RTHCOLD × RTHHOT ×
V
V
TCO
LTF
=
V
V
RTHHOT × VREF - 1 - RTHCOLD × VREF - 1
VLTF
VTCO
RT1
VVREF
-1
VLTF
=
1
1
+
RT2
RTHCOLD
(10)
(11)
JULY 2022
20
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
DETAILED DESCRIPTION (continued)
Using a 103AT type NTC thermistor in the battery pack and
selecting TCOLD = 0℃ and THOT = 45℃ range for Li-Ion or
Li-polymer battery, and recalling the NTC resistances at
temperature limits from datasheet:
RTHCOLD = 27.28kΩ (103AT NTC resistance at 0℃)
RTHHOT = 4.911kΩ (103AT NTC resistance at 45℃)
The resistors can be calculated as:
RT1 = 5.29kΩ
RT2 = 32.12kΩ
The actual temperature range can be calculated based on the
selected standard resistor values and NTC actual
characteristics.
VREF
SGM41526/7
If a charge timer fault occurs, the device recovery process will
depend on the battery voltage as follows.
Case 1: If VBAT exceeds the recharge threshold when the
time-out fault occurs, the charge will be suspended firstly.
When the battery voltage falls below recharge threshold, the
battery detection begins again, and then the timer fault is
cleared. The fault will also clear by a power-on-reset (POR) or
by pulling the ISET voltage below 30mV.
Case 2: If VBAT falls below the recharge threshold when the
timer fault occurs, a small charge current is applied to detect
the battery removal at first. The small charge current is not
removed until VBAT exceeds the recharge threshold. Then the
small charge current is disabled. The rest of recovery process
is as explained in case 1.
Design of the Inductor, Capacitor and
Sense Resistor
RT1
For the charger internal compensation, the best stability is
achieved if the LC filter resonant frequency (fO) given in
Equation 12 is approximately between 15kHz and 25kHz:
TS
RT2
Recovery from Timer Fault
RTH
103AT
fO =
1
(12)
2π LC
Some typical LC values for various charge currents are given
in Table 2.
Figure 7. Battery Pack Temperature Sensing Network
MOSFET and Inductor Protection in Short
Circuit Condition
The SGM41526 and SGM41527 provide cycle-by-cycle short
circuit protection by monitoring the voltage drop across RDS(ON)
of the MOSFETs. If a short is detected, the charger will be
latched off, which means the Buck converter is disabled but
the ACFET will not be turned off, and system is still connected
to the adaptor. Latch-off state can only be removed by
unplugging and re-plugging the input power (adapter). The
LED connected to STAT pin blinks at this condition.
Thermal Regulation and Shutdown
The low thermal impedance of the TQFN package provides
good cooling for the silicon. When the junction temperature
exceeds +120℃, the thermal regulation is triggered. Then the
device will decrease charge current to reduce internal heat
generation. Moreover, if the junction temperature exceeds the
shutdown level (TSHUT = +150℃), charger is turned off and
will not resume until TJ falls below +130℃.
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Table 2. LC Typical Values vs. Designed Charge Current
Charge Current
1A
2A
3A
4A
Output Inductor L
6.8µH
3.3µH
3.3µH
2.2µH
Output Capacitor C
10µF
20µF
20µF
30µF
STAT Charge Status Output
STAT is an open-drain output that indicates the charger status
as explained in Table 3. This pin can be used for driving LEDs
or informing the host about charge status.
Table 3. STAT Output Pin States
Charge State
STAT Transistor
Charge in Progress (including Recharging)
ON
Charge Completed, Sleep Mode, Charge Disabled
OFF
Charge Suspend, Input Over-Voltage, Battery
Over-Voltage, Timer Fault, Battery Absent
BLINK
JULY 2022
21
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
DETAILED DESCRIPTION (continued)
The SGM41526 and SGM41527 are stand-alone switching
chargers and power path selectors. They operate from a
qualified adapter or DC supply system. This device is capable
of providing dynamic power management (DPM mode) to
reduce the input loading by sharing the load with the battery
on the peak system demands. Because of DPM capability,
the adaptor size and power rating can be reduced effectively
for the systems with highly dynamic loads.
The gate drive pins for power path selector switches (ACDRV
and CMSRC) control the input NMOS pair, ACFET (Q1) and
RBFET (Q2). The nBATDRV pin controls the gate of the
battery connection PMOS switch (Q3). If the input (adapter) is
qualified, system will be connected to the input by turning Q1
and Q2 on. Otherwise, Q3 will be turned on then the system
is powered from battery. Moreover, the battery cannot feed
back to the input with power path selection control.
DPM capability is included in the SGM41526 and SGM41527
to limit maximum power taken from the input (adapter) by
reducing the charge current when the system power demand
is high. Input current is accurately sensed to monitor power
usage. Without DPM, the adapter must be designed to
provide maximum charge power plus maximum system power.
However, with DPM, the adapter can be designed for
significantly lower power rating that reduces the size and cost
of the adapter.
SG Micro Corp
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The SGM41526 and SGM41527 can operate independently.
However, some pin settings can be adjusted by an external
controller (like ISET or ACSET). This allows the
implementation of ″battery learn mode″ for applications with
dynamic charging conditions.
Figure 8 shows the typical efficiency of a 4A charger for a
2-cell application.
100
VIN = 15V, 2 Cells
VBAT = 7.6V
95
Efficiency (%)
Device Functional Modes
90
85
80
75
70
0
1000
2000
3000
4000
Charge Current (mA)
Figure 8. Typical Charge Efficiency
JULY 2022
22
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
APPLICATION INFORMATION
Design Requirements
SGM41526 and SGM41527 can be used in portable
applications with up to 4-cell Li-Ion or Li-polymer batteries.
The SGM41526 accurately regulates the battery voltage at a
fixed 4.2V/cell value (minimum 2 cells) and with low leakage
from battery. Number of cells is programmable by CELL pin.
For the applications that need custom battery regulation
voltage or use only one cell, the SGM41527 can be used. In
this variant, the battery regulation voltage is adjustable
through the FB pin similar to a conventional voltage regulator.
Figure 9 shows a typical application circuit of the SGM41526
with a 2-cell battery (8.4V).
As an example to explain the design procedure, suppose that
a charger is needed with the parameters listed in Table 4.
Table 4. Design Requirements
For power input, an adapter or power supply from 4.5V to 22V
is needed generally. The minimum voltage range depends on
the number of battery cells. Typically, the adapter current
rating should be 500mA and higher.
12V
Adapter
Input
IIN
Q1
VIN
RIN
2Ω
CIN
2.2μF
C13
4.7nF
18V (MAX)
Charge Current
4A (MAX)
VSYS
R7
100kΩ
SGM41526
R1 10Ω
AVCC
VREF
R2
232kΩ
Q3
L
3.3μH
ISET
ACSET
Floating
R10
1.5kΩ
D3
CELL
Thermal
STAT Pad
(AGND)
RSR
10mΩ
C5
0.047μF
C8
0.1μF
BTST
PGND
TTC
VBAT
C9
10μF
C10
10μF
IBAT
C6
1μF
C7
0.1μF
SRP
SRN
TS
System
R14 1kΩ
D4
REGN
IOUT
C4
10μF
SW
OVPSET
R3
32.4kΩ
R5
22.1kΩ
600mA (MIN)
Battery Voltage
ACDRV
VREF
C2
1μF
Input Current DPM Limit
The maximum battery voltage shows that a 4-cell battery is
considered in the design.
C1
1μF
R4
100kΩ
4.5V to 22V
C12
0.1μF
R12
ACN PVCC
ACP
4.02kΩ
CMSRC
nBATDRV
R6 1MΩ
D2
Input Voltage Range
C11
0.1μF
R15
C14
47nF 499kΩ
R11
4.02kΩ
VBAT
Example Value
RAC
10mΩ
Q2
D1
Parameter
VREF
RT
103AT
R8
5.23kΩ
C3
0.1μF
R9
30.1kΩ
NOTE: 12V input, 2-cell battery 8.4V, 2A charge current, 0.2A pre-charge/termination current, 3A DPM current, 17.6V input OVP, 0℃ to 45℃ TS.
Figure 9. Typical SGM41526 Schematic for a 2-Cell Battery Application
SG Micro Corp
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JULY 2022
23
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
APPLICATION INFORMATION (continued)
Inductor Selection
Small inductors and capacitors can be used in this design due
to the high switching frequency of the device (fSW = 1.6MHz).
The inductor should not saturate at the highest current that
occurs at maximum charge current plus half peak value of the
ripple current as given in Equation 13:
ISAT ≥ ICHG + (1/2)IRIPPLE
(13)
where ICHG is the charging current, and IRIPPLE is the ripple
current magnitude (peak-to-peak of the AC component).
Except for light loads, the inductor current is continuous and
the IRIPPLE is determined by the following equation:
IRIPPLE =
VIN × D (1- D )
fS × L
(14)
where VIN is the input voltage, D = VOUT/VIN is duty cycle, and
L is the inductance value.
Usually the highest ripple current is generated when duty
cycle is equal to or near 0.5. Inductor current ripple is typically
chosen to be 20% to 40% of the full load DC current to get a
reasonable compromise between inductor size and AC losses.
Higher ripple results in smaller inductor but with lower
efficiency. The highest input voltage and charge current ranges
should be considered for inductor design. Consider 30%
ripple for this design (IRIPPLE ≤ 0.3ICHG):
0.3 × 4A ≥
22V × 0.5 × (1- 0.5 )
1.6MHz × L
(15)
Or L ≥ 2.9μH.
The initial tolerance of the commercial inductors is usually
quite large (typically 10% - 20% and in some cases as high as
30%). The inductance also drops with higher currents
(typically in the order of 20% at maximum current). Therefore,
a good margin must be considered for selection of the
inductor value by consideration of the initial tolerance,
thermal and maximum current drops from the inductor
datasheet. For this example, a 3.3μH inductor is considered.
L = 3.3μH (nominal value of the inductor)
The minimum inductor saturation current from Equation 13 is:
1
ISAT ≥ 4A + × 0.3 × 4A → ISAT ≥ 4.6A
2
Inductor core type and form factor can be designed based on
the required size, loss, magnetic noise coupling, cost, stock
availability and reliability considerations.
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Input Path Capacitors
The input capacitors carry two types of AC currents: (1) the
converter switching ripple currents and (2) the high frequency
(HF) transient currents of the switching. High frequency
decoupling capacitors are necessary to prevent voltage
ringing due to HF currents. Usually some bulk capacitance is
needed to avoid large input rail voltage ripples. Typically, a
ceramic capacitor placed close to the switching leg (PVCC
and PGND) is sufficient to circulate the switching frequency
and high frequency AC currents. This capacitor needs to have
low ESR and ESL. The capacitor self-resonance frequency
should be selected well above switching frequency.
Otherwise, it will not be able to bypass HF switching transient
currents and large ringing noise may be seen on the PVCC. A
combination of smaller size and larger size capacitors may be
used for better noise suppression. Stable ceramic capacitors
such as X5R or X7R are recommended. All capacitors should
be able to carry the peak RMS current of the ripples. Input
capacitor ripple current (ICIN) can be calculated from Equation
16:
ICIN = ICHG × D × (1- D )
(16)
The highest ripple occurs at D = 0.5 and the worst case RMS
ripple current is 0.5ICHG (2A for this example).
Due to the capacitance drop at higher DC voltage bias and
aging, a good margin should be considered for selection of
the capacitor voltage rating. For a 20V maximum input, a 25V
capacitor works. However, a 35V or higher voltage capacitor
is recommended. For a high current (3A ~ 4A) charger, a
minimum of 20μF input capacitance is recommended. For
lower currents (1A or less), 10μF capacitance is sufficient.
Output Capacitor Selection
Applying a charge current with high ripple will deteriorate the
battery lifetime and generate extra loss and heat. Therefore, it
is important to bypass the inductor ripple using output
capacitors and to keep the voltage ripple low, allowing only
the DC current to flow and charge the battery. The output
capacitors should have enough RMS current rating to carry
the worst-case current ripples. The output RMS current (ICOUT)
can be calculated as:
ICOUT=
IRIPPLE
2× 3
≈ 0.29 × IRIPPLE
(17)
The output ripple is given by Equation 18:
V
V
∆VO =OUT 2 1- OUT
8LCfS
VIN
(18)
JULY 2022
24
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
APPLICATION INFORMATION (continued)
The ripple can be reduced by decreasing the cut-off
frequency of the LC filter ( fr =
1
2π LC
). The SGM41526 and
SGM41527 internal loop compensator is designed for a
cut-off frequency of 15kHz to 25kHz. Therefore, in order to
achieve good loop stability, select the output capacitor such
that LC filter cut-off frequency is in the specified range. Stable
ceramic capacitors (like X5R or X7R) are recommended with
enough margin for the rated voltage (25V or higher).
Selecting COUT = 20μF (two parallel 10μF) will result in fr =
19.6kHz with the selected L = 3.3μH inductor.
equivalent ESR for damping of hot plug-in spikes. Ri and Ra
should have sufficient package size and power rating to
dissipate inrush current losses without overheating. A final test
is recommended to assure all requirements are satisfied in the
worst conditions and to make the necessary adjustments.
D1
Adapter
Input
Input Filter Design
Most portable applications must be able to handle hot adapter
plug-in and removal. The parasitic line inductance of the
adapter and the input capacitors of the charger form a
second-order LC circuit that may create a transient
over-voltage on the AVCC and damage the device. So careful
design of the input filter with proper damping is important to
assure the voltage peaks are well below the device limit. A
common method is using a high ESR electrolytic input
capacitor to damp the over-voltage spike. A TVS Zener diode
with high current capability may also be used on the AVCC
pin to clamp the transient peaks. If a more flexible and
compact solution is needed, the input filter shown in Figure 10
can be used. In this network, RiCi filter damps the hot-plug
oscillations and limits the over-voltage spikes to a safe level.
D1 provides reverse voltage protection if a reverse polarity
adapter is mistakenly connected or when the battery is also
feeding AVCC. Ca is the decoupling capacitor of the AVCC that
is placed right beside the AVCC and AGND pins. RaCa filter
provides more damping and reduction of the dv/dt and
magnitude of voltage spike. Ra also serves as a current limiter.
Ca is typically less than the Ci, so Ri dominates in the total
Q1
ADAPTER
RIN
2Ω
CIN
2.2μF
Ca
0.1μF ~ 1μF
AGND
Low RDS(ON), N-type MOSFETs are used for ACFET(Q1) and
RBFET(Q2) as shown in Figure 11. Due to the relatively large
amount of capacitance on the system power rail, PVCC and
charger output, a large inrush current can flow in the switches
if it is not managed properly. Slow turn-on of Q1 can reduce
the inrush current. MOSFETs with relatively large drain-gate
and gate-source parasitic capacitances (CGD and CGS) have
slower turn-on time. External capacitors may be used if Q1
turn-on is not slow enough. As an example, external CGD =
4.7nF and CGS = 47nF can be used across Q1. Current and
power rating of these switches should be selected with good
margin compared to the maximum current from the adapter.
RSNS
SYS
C4
1μF
R12
4.02kΩ
R11
4.02kΩ
Ci
2.2μF
AVCC
Selecting Input Switch Pair (ACFET and
RBFET)
RGS
499kΩ
CGD
Ra
4.7Ω ~ 30Ω
(1206)
Figure 10. Input Filter
Q2
CGS
Ri
2Ω
(2010)
CSY S
40μF
PVCC
CMSRC
ACDRV
Figure 11. External Capacitors to Slowdown Q1 Turn-On and Limit Inrush Current
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JULY 2022
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SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
APPLICATION INFORMATION (continued)
Design Examples
IIN
20V
Adapter
Input
RAC
20mΩ
RevFET Q4
VIN
C11
0.1μF
R12
4.02kΩ
VSYS
C12
0.1μF
SGM41526
R11 5Ω
AVCC
C1
1μF
BTST
VREF
R2
100kΩ
ACSET
R5A
32.4kΩ
R10
1.5kΩ
D3
Thermal
Pad
STAT
(AGND)
C9
10μF
C8
0.1μF
C10
10μF
IBAT
C6
1μF
PGND
C7
0.1μF
SRP
SRN
CELL
VBAT
D2
Optional
ISET
R3
32.4kΩ
RSR
10mΩ
C5
0.047μF
D1
REGN
VREF
ILIM_500mA
SW
OVPSET
R7
78.7kΩ
R5B
8.06kΩ
L
3.3μH
ACDRV
R6 1MΩ
C2
1μF
System
C4
10μF
PVCC
ACN
ACP
CMSRC
nBATDRV
R11
4.02kΩ
R4
100kΩ
IOUT
RT
103AT
VREF
R8
6.81kΩ
TS
R9
133kΩ
TTC
NOTE: Adapter input 20V OVP 22V, up to 4A charge current, 0.4A pre-charge current, 2A adapter current or 500mA USB current,
5℃ to 40℃ TS, system connected before sense resistor.
Figure 12. Typical Application Schematic with 4-Cell Unremovable Battery (OVP 20V)
15V
Adapter
Input
Q1
VIN
IIN
RIN
2Ω
CIN
2.2μF
RAC
10mΩ
Q2
C11
C12
0.1μF
0.1μF
R12
ACN PVCC
ACP
4.02kΩ
CMSRC
nBATDRV
R13
C14
47nF 499kΩ
C13
4.7nF
R11
4.02kΩ
R7
49.9kΩ
Battery Learn
VREF
Learn
R15 FB
+
599kΩ
OVPSET
C5
0.047μF
BTST
SGM41527
PGND
D1
RSR
10mΩ
C8
0.1μF
VBAT
C9
20μF
C10
10μF
R1
499kΩ
C6
1μF
IBAT
R2
100kΩ
C7
0.1μF
SRP
D2
R17 10Ω
VREF
R4
100kΩ
AVCC
C1
1μF
SRN
VREF
R18
100kΩ
ISET
R19
32.4kΩ
C2
1μF
Q3
L
2.2μH
SW
REGN
R16
499kΩ
VBAT
R14 1kΩ
D4
R10
49.9kΩ
System
C4
10μF
ACDRV
R6 499kΩ
IOUT
VSYS
R3
1.5kΩ
D3
Thermal
Pad
STAT (AGND)
R8
5.23kΩ
TS
ACSET
R5
32.4kΩ
VREF
FB
TTC
C3
0.1μF
RT
103AT
R9
30.1kΩ
NOTE: 15V input, 3-cell battery 12.6V, 4A charge current, 0.4A precharge/termination current, 4A DPM current, 0℃ to 45℃ TS.
Figure 13. A Typical 3-Cell Application Schematic with Battery Learn Function
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JULY 2022
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SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
APPLICATION INFORMATION (continued)
5V
Adapter
Input
IIN
VSYS
VIN
IOUT
System
C4
10μF
ACN
ACP
CMSRC
SW
OVPSET
R7
100kΩ
SGM41527
R11 5Ω
REGN
VREF
R5B
12.1kΩ
PGND
ISET
SRP
SRN
R5A
12.1kΩ
FB
ILIM_500mA
TS
ACSET
R10
1.5kΩ
D3
STAT
C5
0.047μF
D1
BTST
AVCC
C1
1μF
R4
Selectable 100kΩ
Current Limit
C2
1μF
L
3.3μH
ACDRV
R6 400kΩ
VREF
PVCC
nBATDRV
Thermal
Pad
(AGND)
TTC
RSR
20mΩ
C8
0.1μF
D2
VBAT
C9
10μF
C10
10μF
R1
100kΩ
C6
1μF
IBAT
R2
100kΩ
C7
0.1μF
VREF
R8
5.23kΩ
RT
103AT
R9
30.1kΩ
NOTE: USB with 8V input OVP, 900mA or 500mA selectable charge current limit, 0℃ to 45℃ TS, system connected after sense resistor.
Figure 14. Typical Application Schematic with Single-Cell Unremovable Battery
Layout Guidelines
A good PCB layout is critical for proper operation of the
switching circuits. A list of important considerations for
SGM41526 and SGM41527 layout design are provided here:
1. The switching node (SW) creates very high frequency
noises several times higher than fSW (1.6MHz) due to sharp
rise and fall times of the voltage and current in the switches.
To reduce the ringing issues and noise generation, it is
important to minimize impedance and loop area of the AC
current paths. A graphical guideline for the current loops and
their frequency content is provided in Figure 15.
2. Input and other decoupling capacitors must be placed as
close to the device pin and ground as possible with the
shortest copper trace and on the same layer of PCB.
3. Surface area of the SW node should be minimized to
reduce capacitive HF noise coupling. Use a short and wide
track connection to the inductor on the same layer of PCB.
Keep sensitive and high impedance traces away from
switching node and trace.
4. Place the charge current-sense resistor right next to the
inductor and use the same layer of PCB for routing them to
the device amplifier input while keeping them close together
and away from high current paths.
Figure 16 shows the proper Kelvin connection of shunt
resistors for accurate current sensing. Use decoupling
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capacitors at the point of connection to the device (between
sense traces and between one of them and AGND).
5. Output capacitors should be placed right next to the sense
resistor.
6. Keep input and output capacitor ground returns tied together
and on the same layer before connecting them to the device
PGND. Having all of them connected in a small geometric
area right beside the device is highly recommended.
7. Keep AGND separated from PGND and connect them only
in a single point under the device body and connect it to the
thermal pad. Use AGND copper pour only under the device. A
0Ω resistor can be used for single point connection of AGND
and PGND. Make connections to AGND with star geometry.
8. For proper cooling of the device, use several thermal vias
connecting the thermal pad pour to the GND plane on the
opposite side and other layers of the PCB. Use enough solder
for thermal pad connections. Open via holes allow solder to
penetrate to the other side and provide low thermal resistance.
Apply solder to the opposite side thermal ground for better
connection to the vias and better thermal cooling. Thermal
ground should not be connected to PGND planes.
9. Remember that vias add some parasitic impedance
(resistive/inductive) to the trace. So, it is generally
recommended to avoid vias in the sensitive or high frequency
paths.
JULY 2022
27
SGM41526
SGM41527
1.6MHz Synchronous Li-Ion/Li-Polymer Stand-Alone
Battery Chargers with Automatic Power Path Selector
APPLICATION INFORMATION (continued)
L
SW
DC IN
HF Noise
Coupling Current Path for
Ripple Current
(Switching Frequency
and the Low Order
Harmonics)
Current Path
Containing Very
High Frequency
and Switching
Frequency
CIN
(IAC ≈ 0)
BAT
C
PGND
Keep these PGND points
close together
Figure 15. Graphical Representation of the Switching and Transient Current Loops, and Capacitive Noise Coupling from
SW Node
Current Direction
RSNS
Current Sensing Direction
To SRP and SRN Pin
Figure 16. Sensing Resistor PCB Layout
REVISION HISTORY
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Original (JULY 2022) to REV.A
Page
Changed from product preview to production data .................................................................................................................................................All
SG Micro Corp
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JULY 2022
28
PACKAGE INFORMATION
PACKAGE OUTLINE DIMENSIONS
TQFN-5.5×3.5-24L
e1
k
D
N1
N24
N2
N23
D1
E1
E
e
N12
N13
b
b1
L
TOP VIEW
BOTTOM VIEW
4.1
2.7
0.70
2.05
A
SIDE VIEW
A1
A2
4.7
4.05
0.5
0.25
1.5
6.1
0.20
RECOMMENDED LAND PATTERN (Unit: mm)
Symbol
Dimensions
In Millimeters
MIN
MAX
Dimensions
In Inches
MIN
MAX
A
0.700
0.800
0.028
0.031
A1
0.000
0.050
0.000
0.002
A2
0.203 REF
0.008 REF
D
3.400
3.600
0.134
0.142
D1
1.950
2.150
0.077
0.085
E
5.400
5.600
0.213
0.220
E1
3.950
4.150
0.156
0.163
k
0.325 REF
0.013 REF
b
0.200
0.300
0.008
0.012
b1
0.150
0.250
0.006
0.010
L
0.300
0.500
0.012
0.020
e
0.500 BSC
0.020 BSC
e1
1.500 BSC
0.059 BSC
SG Micro Corp
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TX00122.000
PACKAGE INFORMATION
TAPE AND REEL INFORMATION
REEL DIMENSIONS
TAPE DIMENSIONS
P2
W
P0
Q1
Q2
Q1
Q2
Q1
Q2
Q3
Q4
Q3
Q4
Q3
Q4
B0
Reel Diameter
A0
P1
K0
Reel Width (W1)
DIRECTION OF FEED
NOTE: The picture is only for reference. Please make the object as the standard.
KEY PARAMETER LIST OF TAPE AND REEL
Reel
Diameter
Reel Width
W1
(mm)
A0
(mm)
B0
(mm)
K0
(mm)
P0
(mm)
P1
(mm)
P2
(mm)
W
(mm)
Pin1
Quadrant
TQFN-5.5×3.5-24L
13″
12.4
3.80
5.80
1.00
4.0
8.0
2.0
12.0
Q1
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TX10000.000
DD0001
Package Type
PACKAGE INFORMATION
CARTON BOX DIMENSIONS
NOTE: The picture is only for reference. Please make the object as the standard.
KEY PARAMETER LIST OF CARTON BOX
Length
(mm)
Width
(mm)
Height
(mm)
Pizza/Carton
13″
386
280
370
5
SG Micro Corp
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DD0002
Reel Type
TX20000.000
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