SEMTECH SC820

SC820
Adapter/USB Dual Input
Single-cell Li-ion Charger
POWER MANAGEMENT
Features
Description
„
The SC820 is a dual input (adapter/USB) linear single-cell
Li-ion battery charger in an 8 lead 2x2 MLPD ultra-thin
package. Both inputs will survive sustained input voltage
up to 30V to protect against hot plug overshoot and faulty
charging adapters.
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Dual input charger automatically selects adapter
input over USB
Constant voltage — 4.2V, 1% regulation
Fast-charge current regulation — 15% at 70mA,
9% at 700mA
Three mode charging (current regulation, voltage
regulation, thermal limiting)
Input voltage protection — 30V
Current-limited adapter charging support — reduces
power dissipation in charger
USB input limits charge current to prevent Vbus
overload
Instantaneous CC-to-CV transition for faster charging
Programmable battery-dependent currents (adaptersourced fast-charge & pre-charge, termination)
Programmable source-limited currents (USB-sourced
fast-charge & pre-charge)
Three termination options — float-charge, automatic
re-charge, or forced re-charge to keep the battery
topped-off after termination without float-charging
Soft-start reduces adapter or USB load transients
High operating voltage range permits use of
unregulated adapters
Complies with CCSA YD/T 1591-2006
Space saving 2x2x0.6 (mm) MLPD package
WEEE and RoHS compliant
Charging begins automatically when a valid input source
is applied to either input. The adapter input is selected
when both input sources are present.
Thermal limiting protects the SC820 from excessive power
dissipation when charging from either source. The SC820
can be programmed to turn off when charging is complete
or to continue operating as an LDO regulator while floatcharging the battery.
The adapter input charges with an adapter operating in
voltage regulation or in current limit to obtain the lowest
possible power dissipation by pulling the VAD input
voltage down to the battery voltage. The VUSB input
automatically limits load current to prevent over-loading
the USB Vbus supply.
Charge current programming requires two resistors. One
determines battery-capacity dependent currents: adapter
input fast-charge current, pre-charge current, and charge
termination current. The other independently determines
input-limited USB charging currents: USB input fastcharge and pre-charge current.
Applications
„
Mobile phones
MP3 players
„ GPS handheld receivers
„
Typical Application Circuit
SC820
VAD
VADAPTER
VUSB
USB Vbus
2.2 μF
February 26, 2008
2.2 μF
Battery
Pack
ENB
Device
Load
BAT
STATB
IPRGM
GND
IPUSB
© 2008 Semtech Corporation
2.2 μF
1
SC820
Pin Configuration
VAD
Ordering Information
1
8
ENB
TOP VIEW
VUSB
2
7
BAT
STATB
3
6
IPRGM
5
IPUSB
Device
Package
SC820ULTRT(1)(2)
MLPD-UT-8 2×2
SC820EVB
Evaluation Board
Notes:
(1) Available in tape and reel only. A reel contains 3,000 devices.
(2) Lead-free package only. Device is WEEE and RoHS compliant.
T
GND
4
MLPD-UT8; 2x2, 8 LEAD
θJA = 68°C/W
Marking Information
820
yw
yw = Date Code
2
SC820
Absolute Maximum Ratings
Recommended Operating Conditions
VAD and VUSB (V) . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +30.0
Operating Ambient Temperature (°C) . . . . . . . . . -40 to +85
BAT, IPRGM, IPUSB (V) . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.5
STATB, EN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to VBAT +0.3
VAD Input Current (A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 . 5
Thermal Information
VUSB Input Current (A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 . 5
Thermal Resistance, Junction to Ambient(2) (°C/W) . . . . . 68
BAT, IPRGM, IPUSB Short-to-GND Duration . . . . . Continuous
Junction Temperature Range (°C) . . . . . . . . . . . . . . . . . . +150
Total Power Dissipation (W) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Storage Temperature Range (°C) . . . . . . . . . . . . -65 to +150
ESD Protection Level(1) (kV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Peak IR Reflow Temperature (10s to 30s) (°C) . . . . . . . +260
Exceeding the above specifications may result in permanent damage to the device or device malfunction. Operation outside of the parameters
specified in the Electrical Characteristics section is not recommended.
NOTES:
(1) Tested according to JEDEC standard JESD22-A114-B.
(2) Calculated from package in still air, mounted to 3 x 4.5 (in), 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards.
Electrical Characteristics
Test Conditions: VVAD = VVUSB = 4.75V to 5.25V; VBAT = 3.7V; Typ values at 25°C; Min and Max at -40°C < TA < 85°C, unless specified.
Parameter
Min
Typ
Max
Units
VAD-OP
4.60
5.00
8.20
V
VAD Select Rising Threshold
VTADsel-R
4.30
4.45
4.60
V
VAD Deselect Falling Threshold (2)
VTADsel-F
2.70
2.85
3.00
V
USB Input Operating Voltage (1)
VUSB-OP
4.35
5.00
8.20
V
4.20
4.35
V
VAD Operating Voltage (1)
Symbol
Conditions
VVAD > VBAT
VUSB Select Rising Threshold
VTUSBsel-R
VVUSB > VBAT
VUSB Deselect Falling Threshold
VTUSBsel-F
VVUSB > VBAT
3.65
VUSB Select Hysteresis
VTUSBsel-H
VTUSBsel-R - VTUSBsel-F
100
OVP Rising Threshold
VTOVP-R
VAD or VUSB input
OVP Falling Threshold
VTOVP-F
VAD or VUSB input
8.2
V
OVP Hysteresis
VTOVP-H
(VTOVP-R - VTOVP-F)
50
mV
VAD Charging Disabled Quiescent
Current
IqVAD_DIS
VVUSB = 0V, VENB = VBAT
2
3
mA
VAD Charging Enabled Quiescent
Current
IqVAD_EN
VVUSB = 0V, VENB = 0V,
excluding IBAT, IIPRGM, and IIPUSB
2
3
mA
VUSB Charging Disabled Quiescent
Current
IqVUSB_DIS
VVAD = 0V; VENB = VBAT
2
3
mA
VUSB Charging Enabled Quiescent
Current
IqVUSB_EN
VVAD = 0V, VENB = 0V,
excluding IBAT, IIPRGM, and IIPUSB
2
3
mA
4.00
V
mV
9.6
V
3
SC820
Electrical Characteristics (continued)
Parameter
Symbol
Conditions
VUSB Deselected Quiescent Current(3)
IqVUSB_DES
VVAD ≥ VVUSB
VCV
IBAT = 50mA, -40°C ≤ TJ ≤ 125°C
4.16
VCV_LOAD
Relative to VCV @ 50mA,
VVAD = 5V, or VVUSB = 5V and VVAD = 0V,
-20
CV Regulation Voltage
CV Voltage Load Regulation(4)
Min
Typ
Max
Units
25
50
μA
4.20
4.24
V
10
mV
1mA ≤ IBAT ≤ 700mA, -40°C ≤ TJ ≤ 125°C
Re-charge Threshold
VTReQ
Pre-charge Threshold (rising)
VTPreQ
Battery Leakage Current
VCV — VBAT
60
100
140
mV
2.85
2.90
2.95
V
lBAT_V0
VBAT = VCV, VVAD = VVUSB = 0V
0.1
1
μA
lBAT_DIS
VBAT = VCV, VVAD = VVUSB = 5V, VENB = 2V
0.1
1
μA
lBAT_MON
VBAT = VCV, VVAD = VVUSB = 5V,
ENB not connected
0.1
1
μA
29.4
kΩ
IPRGM Programming Resistor
RIPRGM
Fast-Charge Current, VAD input
IFQ_AD
RIPRGM = 2.94kΩ, VTPreQ < VBAT < VCV
643
694
745
mA
Pre-Charge Current, VAD input
IPreQ_AD
RIPRGM = 2.94kΩ, 1.8V < VBAT < VTPreQ
105
139
173
mA
ITERM
RIPRGM = 2.94kΩ, VBAT = VCV
59
69
80
mA
VAD to BAT Dropout Voltage
VDO_AD
IBAT = 700mA, 0°C ≤ TJ ≤ 125°C
0.75
1.0
V
IPUSB Programming Resistor
RIPUSB
29.4
kΩ
Fast-Charge Current, VUSB input
IFQ_USB
RIPUSB = 4.42kΩ, VTPreQ < VBAT < VCV
427
462
497
mA
Pre-Charge Current, VUSB input
IPreQ_USB
RIPUSB = 4.42kΩ, 1.8V < VBAT < VTPreQ
69
92
116
mA
VUSB to BAT Dropout Voltage
VDO_USB
IBAT = 500mA, 0°C ≤ TJ ≤ 125°C
0.55
1
V
IPRGM Fast-charge Regulated Voltage
VIPRGM_FQ
VVAD = 5.0V, VVUSB = 0V,
VTPreQ < VBAT < VCV
2.04
V
IPRGM Pre-charge Regulated Voltage
VIPRGM_PQ
VBAT < VTPreQ
0.408
V
IPRGM Termination Threshold Voltage
VTIPRGM_TERM
VBAT = VCV (either input selected)
0.204
V
IPUSB Fast-charge Regulated Voltage
VIPUSB_FQ
VVAD = 0V, VTPreQ < VBAT < VCV
2.04
V
IPUSB Pre-charge Regulated Voltage
VIPUSB_PQ
VVAD = 0V, VBAT < VTPreQ
0.408
V
VUSB Under-Voltage Load Regulation
Limiting Voltage
VVUSB_UV_LIM
5mA ≤ VUSB supply current limit ≤
500mA, VVAD = 0V,
RIPUSB = 3.65kΩ (559mA)
Termination Current, either input
2.05
2.05
4.45
4.58
4.70
V
4
SC820
Electrical Characteristics (continued)
Parameter
Symbol
Conditions
Min
Typ
Max
Units
Thermal Limiting Threshold
Temperature
T TL
130
°C
Thermal Limiting Rate
iT
50
mA/ °C
ENB Input High Voltage
VIH
1.6
ENB Input Mid Voltage
VIM
0.7
ENB Input Low Voltage
VIL
V
1.3
V
0.3
V
ENB Input High-range Threshold
Input Current
IIH_TH
ENB current required to pull ENB from
floating midrange into high range
23
50
μA
ENB Input High-range Sustain Input
Current
IIH_SUS
Current required to hold ENB in
high range, Min VIH ≤ VENB ≤ VBAT,
Min VIH ≤ VBAT ≤ 4.2V
0.3
1
μA
ENB Input Mid-range Load Limit
IIM
Input will float to mid range when this
load limit is observed.
-5
5
μA
ENB Input Low-range Input Current
IIL
0V ≤ VENB ≤ Max VIL
-25
IILEAK
VVIN = 0V, VENB = VBAT = 4.2V
1
μA
STATB Output Low Voltage
VSTAT_LO
ISTAT_SINK = 2mA
0.5
V
STATB Output High Current
ISTAT_HI
VSTAT = 5V
1
μA
ENB Input Leakage
-12
μA
Notes:
(1) Maximum operating voltage is the maximum Vsupply as defined in EIA/JEDEC Standard No. 78, paragraph 2.11. This is the input voltage at
which the charger is guaranteed to begin operation.
(2) Sustained operation to VTADsel-F ≤ VVAD is guaranteed only if a current limited charging source applied to VAD is pulled below VTADsel-R by the
charging load; forced VAD voltage below VTADsel-R may in some cases result in regulation errors or other unexpected behavior.
(3) If VAD is the selected input but VVAD < VVUSB, such as when VAD is operating with an adapter in current limit while a VUSB charging source is
applied, IqVUSB_DES will increase to approximately IqVUSB_EN.
(4) At load currents exceeding 700mA, or at 700mA while at elevated ambient temperature, the charger may enter dropout with a 5V input before
the battery voltage has risen to VCV. See the specification of VDO_AD. Although this is a safe and acceptable mode of operation, specification of
VCV when in dropout is not applicable; higher input voltage will restore the charger to CV regulation in these cases. Note that VBAT is always
less than VCV while in dropout. As the battery state-of-charge increases, the charging current will decrease allowing the battery voltage to rise
to VCV, and CV regulation will begin. This appears as a softening or rounding of the CC-to-CV regulation mode transition, similar to that seen
in chargers with a linear CC-to-CV regulation crossover.
5
SC820
Typical Characteristics
CV Line Regulation
CV Load Regulation
ο
ο
TA = 25 C, VVAD = 5V
4.204
4.204
4.2
4.2
4.196
4.196
VBAT (V)
VBAT (V)
TA = 25 C, IBAT = 50mA
4.192
4.192
4.188
4.188
4.184
4.184
4.18
5
5.5
6
6.5
7
7.5
4.18
0
8
100
200
300
400
500
600
700
800
IBAT (mA)
VVAD (V)
CV Temperature Regulation
CC FQ Line Regulation (AD or USB)
ο
VVAD = 5V, IBAT = 50mA
TA = 25 C, VBAT = 3.7V
4.204
720
4.2
680
RIPRGM or RIPUSB = 2.94kΩ
640
IBAT (mA)
VBAT (V)
4.196
4.192
600
560
4.188
520
4.184
4.18
RIPRGM or RIPUSB = 4.42kΩ
480
-40
-20
0
20
40
60
80
100
440
4.5
120
5
5.5
6
o
CC FQ VBAT Regulation (AD or USB)
7.5
8
VVAD = 5V, VBAT = 3.7V
720
720
680
680
RIPRGM or RIPUSB = 2.94kΩ
640
640
IBAT (mA)
IBAT (mA)
7
CC FQ Temperature Regulation (AD or USB)
ο
TA = 25 C, VVAD = 5V
600
560
520
600
560
520
RIPRGM or RIPUSB = 4.42kΩ
480
440
2.9
6.5
VVAD (V)
Ambient Temperature ( C)
3.1
3.3
3.5
VBAT (V)
3.7
480
3.9
4.1
440
-40
-20
0
20
40
60
80
100
120
o
Ambient Temperature ( C)
6
SC820
Typical Characteristics (continued)
CC PQ Line Regulation (AD or USB)
CC PQ Temperature Regulation (AD or USB)
ο
VVAD = 5V, VBAT = 2.6V
TA = 25 C, VBAT = 2.6V
160
160
150
150
RIPRGM or RIPUSB = 2.94kΩ
IBAT (mA)
IBAT (mA)
RIPRGM or RIPUSB = 2.94kΩ
140
140
130
120
110
130
120
110
RIPRGM or RIPUSB = 4.42kΩ
RIPRGM or RIPUSB = 4.42kΩ
100
100
90
5
5.5
6
6.5
7
7.5
90
8
-40
-20
0
I
vs. R
20
40
60
80
100
120
o
VVAD (V)
Ambient Temperature ( C)
, or IFQ_USB vs. RIPUSB
I
FQ_AD
IPRGM
ο
VVAD = 5V, VBAT = 3.7V, TA = 25 C
vs. R
, or IPQ_USB vs. RIPUSB
PQ_AD
IPRGM
ο
VVAD = 5V, VBAT = 2.6V, TA = 25 C
1000
200
800
600
IBAT (mA)
IBAT (mA)
160
400
80
200
0
2
120
40
6
10
14
18
22
26
30
0
2
6
10
RIPRGM or RIPUSB (kΩ)
14
18
22
26
30
RIPRGM or RIPUSB (kΩ)
CC — Input Reselection, AD to USB
CC — Input Reselection, USB to AD
VBAT=3.7V, VVUSB=5.0V
VBAT=3.7V, VVUSB=5.0V
VVAD (1.0V/div)
VVAD (1.0V/div)
IBAT (200mA/div)
IBAT (200mA/div)
VVAD=0V—
VVAD=0V—
IBAT=0mA—
IBAT=0mA—
400μs/div
400μs/div
7
SC820
Typical Characteristics (continued)
Charging Cycle Battery Voltage and Current
Pre-Charging Battery Voltage and Current
ο
ο
850mAhr battery, RIPRGM = 2.94kΩ, VVAD = 5.0V, TA = 25 C
850mAhr battery, RIPRGM = 2.94kΩ, VVAD = 5.0V, TA = 25 C
800
700
6
600
5
500
700
3.75
400
300
3
IBAT
2
1
0.25
0.5
0.75
1
1.25
1.5
1.75
2
600
3.25
500
400
3
VBAT
2.75
300
200
2.5
200
100
2.25
100
2
0
0
2.25
2
4
6
CC-to-CV Battery Voltage and Current
12
14
16
18
0
20
850mAhr battery, RIPRGM = 2.94kΩ, VVAD = 5.0V, Load = 10mA
710
IBAT
670
650
4.18
VBAT
630
4.17
IBAT (mA)
690
4.19
450
4.5
VBAT (V), Internal Power Dissipation (W)
4.21
VBAT (V)
10
Re-Charge Cycle Battery Voltage and Current
ο
850mAhr battery, RIPRGM = 2.94kΩ, VVAD = 5.0V, TA = 25 C
4.2
8
Time (s)
Time (hrs)
4
400
VBAT
3.5
350
3
300
2.5
250
2
200
IBAT (mA)
0
0
3.5
VBAT (V)
VBAT
4
IBAT
IBAT (mA)
7
IBAT (mA)
VBAT (V), Internal Power Dissipation (W)
4
150
1.5
IBAT
1
100
50
0.5
Discharge hours 2 - 6 omitted.
4.16
44
44.5
45
45.5
46
Time (min)
46.5
47
47.5
610
48
0
0.0
0.5
1.0
1.5
2/6
6.5
7.0
0
7.5
Time (hrs)
8
SC820
Pin Descriptions
Pin #
Pin Name
Pin Function
1
VAD
Supply pin — connect to charging adapter. This pin is protected against damage due to high voltage up to 30V.
2
VUSB
Supply pin — connect to USB Vbus power. Typically 5V, limited load-current input. This pin is protected against
damage due to high voltage up to 30V.
3
STATB
Status output pin — This open-drain pin is asserted (pulled low) when a valid charging supply is connected to
either VAD or VUSB, and a charging cycle begins. It is released when the termination current is reached, indicating
that charging is complete. STATB is not asserted for re-charge cycles.
4
GND
Ground
5
IPUSB
Fast-charge and pre-charge current programming pin for the VUSB power source — VUSB fast-charge current
is programmed by connecting a resistor from this pin to ground. VUSB pre-charge current is 20% of fast-charge
current.
6
IPRGM
Fast-charge and pre-charge current programming pin for the adapter power source — VAD fast-charge current
is programmed by connecting a resistor from this pin to ground. VAD pre-charge current is 20% of fast-charge
current. The charging termination current threshold (for either VAD or VUSB input selection) is 10% of the IPRGM
programmed fast-charge current.
7
BAT
Charger output
8
ENB
Combined device enable/disable — Logic high disables the device. Tie to GND to enable charging with indefinite
float-charging. Float this pin to enable charging without float-charge upon termination. Note that this pin must
be grounded if the SC820 is to be operated without a battery connected to BAT.
T
Thermal Pad
— connect to battery positive terminal.
Pad is for heatsinking purposes — not connected internally. Connect exposed pad to ground plane using
multiple vias.
9
SC820
Block Diagram
V_Adapter
USB_VBUS
1
2
VAD
VUSB
Input Selection Logic
Adapter/USB select
Connect to BAT or
to regulated supply
VVUSB_UV_LIM = 4.575V
VCV = 4.2V
To
System
Load
CV
BAT
7
CC
VIREF
CC
Feedback
Selection
Die
Temperature
Thermal
Limiting
VT_CT
3
LithiumIon
Single
Cell
Battery
Pack
STATB
Pre-charge, CC/
CV & Termination
Controller, Logical
State Machine
Termination
VTIPRGM_TERM
VTENB_HIGH = ~1.50V
1V
Tri-level
Control
VTENB_LOW = ~0.55
ENB
IPRGM
IPUSB
8
5
RIPUSB
GND
6
4
RIPRGM
10
SC820
Applications Information
Charger Operation
The SC820 is a dual-input stand-alone Li-ion battery
charger. The VAD input pin is optimized for a charging
adapter. The VUSB pin is optimized for charging from the
USB Vbus supply. The device is independently programmed for battery-capacity-dependent currents
(adapter fast-charge current and termination current)
using the IPRGM pin. Charging currents from the USB
Vbus supply, which has a maximum load specification,
are programmed using the IPUSB pin.
When an input supply is first detected, a charge cycle is
initiated and the STATB open-drain output goes low. If
the battery voltage is less than the pre-charge threshold
voltage, the pre-charge current is supplied. Pre-charge
current is 20% of the programmed fast-charge current for
the selected input.
When the battery voltage exceeds the pre-charge threshold, typically within seconds for a standard battery with a
starting cell voltage greater than 2V, the fast-charge
Constant Current (CC) mode begins. The charge current
soft-starts in three steps (20%, 60%, and 100% of programmed fast-charge current) to reduce adapter load
transients. CC current is programmed by the IPRGM resistance to ground when the VAD input is selected and by
the IPUSB resistance to ground when the VUSB input is
selected.
The charger begins Constant Voltage (CV) regulation
when the battery voltage rises to the fully-charged singlecell Li-ion regulation voltage (VCV ), nominally 4.2V. In CV
regulation, the output voltage is regulated, and as the
battery charges, the charge current gradually decreases.
The STATB output goes high when IBAT drops below the
termination current threshold, which is 10% of the IPRGM
pin programmed fast-charge current regardless of the
input selected. This is known as charge termination.
Optional Float-charging or Monitoring
Depending on the state of the ENB input, upon termination the SC820 either operates indefinitely as a voltage
regulator (float-charging) or it turns off its output. If the
output is turned off upon termination, the device enters
the monitor state. In this state, the output remains off
until the BAT pin voltage decreases by the re-charge
threshold (VTReQ). A re-charge cycle then begins auto-
matically and the process repeats. A forced re-charge
cycle can also be periodically commanded by the processor to keep the batter y topped-off without
float-charging. See the Monitor State section for details.
Re-charge cycles are not indicated by the STATB pin.
Charging Input Selection
The SC820 has two charging supply input pins. VAD is
optimized for adapter charging. VUSB is optimized for
charging from the USB Vbus power supply. The inputs
differ in selection rising and deselection falling thresholds, their behavior when overloading their respective
charging sources, and in which current programming pin
determines the fast-charge and pre-charge current. Both
use the same Over-Voltage Protection (OVP) threshold.
Glitch filtering is performed on the VAD and VUSB inputs,
so an applied input voltage that is ringing across its selection threshold will not be selected until the ringing has
ceased. When both inputs exceed their respective UVLO
thresholds, VAD is selected even when VAD voltage is
applied while already charging from the VUSB input. VAD
is also selected in the case that the VAD voltage exceeds
its OVP threshold, so that an excessive VAD voltage will
disable charging despite the presence of a valid VUSB
input voltage.
When a valid input (defined as greater than its selection
threshold and less than the OVP threshold) is first
selected, a charge cycle is initiated and the STATB output
is asserted. When a new input selection is made (when
VAD is applied or removed while VUSB is present), the
charge cycle is immediately halted and re-initiated with
the newly selected input. There is a momentary (approximately 1ms) interruption in output current and a release
and re -assertion of the STATB pin during input
reselection.
If the VAD input charging current loads the adapter
beyond its current limit, the VAD input voltage will be
pulled down to just above the battery voltage. The
adapter input deselection falling threshold is set close to
the battery voltage pre-charge threshold to permit lowdissipation charging from a current limited adapter.
The VUSB input provides a higher deselection falling
threshold appropriate to the USB specification. The USB
11
SC820
Applications Information (continued)
input also provides Under-Voltage Load Regulation
(UVLR), in which the charging current is reduced if needed
to prevent overloading of the USB Vbus supply. UVLR can
serve as a low-cost alternative to directly programming
the USB low power charge current. It is also useful where
there is no signal available to indicate whether USB low or
high power mode should be selected.
Constant Current Mode Fast-charge Current
Programming
The Constant Current (CC) mode is active when the
battery voltage is above the pre-charge threshold voltage
(VTPreQ) and less than VCV. When VAD is the selected input,
the programmed CC regulation fast-charge (FQ) current
is inversely proportional to the IPRGM pin resistance to
GND according to the equation
,)4 B $'
9,35*0 B 7\S
5,35*0
When VUSB is the selected input, the programmed CC
mode fast-charge current is inversely proportional to the
IPUSB pin resistance to GND according to the equation
9,386% B 7\S
,)4 B 86%
5,386%
The fast-charge current can be programmed for a
minimum of 70mA and a maximum of 995mA for either
input, nominally. The VAD input is designed for lower
dropout voltage at high current, which ensures charging
without thermal limiting with a charging adapter operating in current limit of at least 700mA.
Current regulation accuracy is dominated by gain error at
high current settings and offset error at low current settings. The range of expected fast-charge output current
versus programming resistance RIPRGM or RIPUSB (for VAD or
VUSB input selected, respectively) is shown in Figures 1a
and 1b. The figures show the nominal current versus
nominal RIPRGM or RIPUSB resistance as the center plot and
two theoretical limit plots indicating maximum and
minimum current versus nominal programming resistance. These plots are derived from models of the
expected worst-case contribution of error sources
depending on programmed current. The current range
includes the uncertainty due to 1% tolerance resistors.
The dots on each plot indicate the currents obtained with
standard value 1% tolerance resistors. Figures 1a and 1b
show low and high resistance ranges, respectively.
Pre-charge Mode
This mode is automatically enabled when the battery
voltage is below the pre-charge threshold voltage (VTPreQ).
Pre-charge current conditions the battery for fast charging. The pre-charge current value is fixed at 20%
nominally of the fast-charge current for the selected
input. The fast-charge current is programmed by the
1100
325
1050
300
1000
950
275
250
850
Fast-charge Current (mA)
Fast-charge Current (mA)
900
800
750
700
650
600
550
500
225
200
175
150
125
450
100
400
350
75
300
250
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
RIPRGM or RIPUSB (kΩ), R-tol = 1%
Figure 1a — Fast-charge Current Tolerance versus
Programming Resistance, Low Resistance Range
50
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
RIPRGM or RIPUSB (kΩ), R-tol = 1%
Figure 1b — Fast-charge Current Tolerance versus
Programming Resistance, High Resistance Range
12
SC820
Applications Information (continued)
resistance between IPRGM and GND for the VAD input,
and by the resistance between IPUSB and GND for the
VUSB input.
Pre-charge current regulation accuracy is dominated by
offset error. The range of expected pre-charge output
current versus programming resistance is shown in Figures
2a and 2b. The figures show the nominal pre-charge
current versus nominal resistance as the center plot and
two theoretical limit plots indicating maximum and
minimum current versus nominal programming resistance. These plots are derived from models of the
expected worst-case contribution of error sources
depending on programmed current. The current range
includes the uncertainty due to 1% tolerance resistors.
The dots on each plot indicate the currents obtained with
standard value 1% tolerance resistors. Figures 2a and 2b
show low and high resistance ranges, respectively.
Termination
When the battery voltage reaches VCV, the SC820 transitions from constant current regulation to constant voltage
regulation. While VBAT is regulated to VCV, the current into
the battery decreases as the battery becomes fully
charged. When the output current drops below the termination current threshold, charging terminates. Upon
termination, the STATB pin open drain output turns off
and the charger either enters monitor state or floatcharges the battery, depending on the logical state of the
ENB input pin.
The termination current threshold is fixed at 10% of the
VAD input fast-charge current, as programmed by the
resistance between IPRGM and GND. The IPRGM pin
resistance determines the termination current threshold
regardless of whether the selected charging input is VAD
or VUSB.
Charger output current is the sum of the battery charge
current and the system load current. Battery charge
current changes gradually, and establishes a slowly
diminishing lower bound on the output current while
charging in CV mode. The load current into a typical
digital system is highly transient in nature. Charge cycle
termination is detected when the sum of the battery
charging current and the greatest load current occurring
within the immediate 300μs to 550μs past interval is less
than the programmed termination current. This timing
behavior permits charge cycle termination to occur
during a brief low-load-current interval, and does not
require that the longer interval average load current be
small.
Termination current threshold accuracy is dominated by
offset error. The range of expected termination current
versus programming resistance RIPRGM (for either VAD or
VUSB input selected) is shown in Figures 3a and 3b. The
figures show the nominal termination current versus
nominal RIPRGM resistance as the center plot and two theoretical limit plots indicating maximum and minimum
current versus nominal programming resistance. These
270
260
80
75
70
230
220
65
210
60
200
190
55
Pre-charge Current (mA)
Pre-charge Current (mA)
250
240
180
170
160
150
140
130
120
110
100
50
45
40
35
30
25
90
20
80
70
15
60
50
10
5
40
30
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
RIPRGM or RIPUSB (kΩ), R-tol = 1%
Figure 2a — Pre-charge Current Tolerance versus
Programming Resistance, Low Resistance Range
0
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
RIPRGM or RIPUSB (kΩ), R-tol = 1%
Figure 2b — Pre-charge Current Tolerance versus
Programming Resistance, High Resistance Range
13
SC820
Applications Information (continued)
115
35
110
105
30
95
Termination Current Threshold (mA)
Termination Current Threshold (mA)
100
90
85
80
75
70
65
60
55
50
45
25
20
15
10
40
35
5
30
25
20
2
0
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
RIPRGM (kΩ), R-tol = 1%
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
RIPRGM (kΩ), R-tol = 1%
Figure 3a — Termination Current Tolerance versus
Programming Resistance, Low Resistance Range
Figure 3b — Termination Current Tolerance versus
Programming Resistance, High Resistance Range
plots are derived from models of the expected worst-case
contribution of error sources depending on programmed
current. The current range includes the uncertainty due
to a 1% tolerance resistor. The dots on each plot indicate
the currents obtained with standard value 1% tolerance
resistors. Figures 3a and 3b show low and high resistance
ranges, respectively.
The equivalent circuit looking into the ENB pin is a variable resistance, minimum 15kΩ, to an approximately 1V
source. The input will float to mid range whenever the
external driver sinks or sources less than 5μA, a common
worst-case characteristic of a high impedance or a weak
pull-up or pull-down GPIO configured as an input. The
driving GPIO must be able to sink or source at least 75μA
to ensure a low or high state, respectively, although the
drive current is typically far less. (See the Electrical
Characteristics table.)
Enable Input
The ENB pin is a tri-level logical input that allows selection
of the following behaviors:
•
•
•
Charging enabled with float-charging after termination (ENB = low range)
Charging enabled with float-charging disabled
and battery monitoring at termination (ENB =
mid range)
Charging disabled (ENB = high range).
If the ENB input voltage is permitted to float to mid-range,
the charger is enabled but it will turn off its output following charge termination and will enter the monitor state.
This state is explained in the next section. Mid-range can
be selected either by floating the input (sourcing or
sinking less than 5μA) or by being externally forced such
that VENB falls within the midrange limits specified in the
Electrical Characteristics table.
This input is designed to interface to a processor GPIO
port powered from a peripheral supply voltage as low as
1.8V or as high as a fully charged battery. While a connected GPIO port is configured as an output, the processor
writes a 0 to select ENB low-range, and 1 to select highrange. The GPIO port is configured as an input to select
mid-range.
When driven low (VENB < Max VIL), the charger is enabled
and will continue to float-charge the battery following
termination. If the charger is already in monitor state following a previous termination, it will exit the monitor state
and begin float-charging.
ENB can also be permanently grounded to select lowrange or left unconnected to select mid-range if it will not
be necessary to change the level selection.
When ENB is driven high (VENB > Min VIH), the charger is
disabled and the ENB input pin enters a high impedance
state, suspending tri-level functionality. The specified
high level input current IIH is required only until a high
14
SC820
Applications Information (continued)
level is recognized by the SC820 internal logic. The trilevel float circuitry is then disabled and the ENB input
becomes high impedance. Once forced high, the ENB pin
will not float to mid range. To restore tri-level operation,
the ENB pin must first be pulled down to mid or low range
(at least to VENB < Max VIM), then, if desired, released (by
reconfiguring the GPIO as an input) to select mid-range. If
the ENB GPIO has a weak pull-down when configured as
an input, then it is unnecessary to drive ENB low to restore
tri-level operation; simply configure the GPIO as an input.
When the ENB selection changes from high-range to midor low-range, a new charge cycle begins and STATB goes
low.
Note that if a GPIO with a weak pull-up input configuration is used, its pull-up current will flow from the GPIO into
the ENB pin while it is floating to mid-range. Since the
GPIO is driving a 1V equivalent voltage source through a
resistance (looking into ENB), this current is small − possibly less than 1μA. Nevertheless, this current is drawn from
the GPIO peripheral power supply and, therefore, from the
battery after termination. (See the next section, Monitor
State.) For this reason, it is preferable that the GPIO chosen
to operate the ENB pin should provide a true high impedance (CMOS) configuration or a weak pull-down when
configured as an input. When pulled below the float
voltage, the ENB pin output current is sourced from VAD
or VUSB, not from the battery.
Monitor State
If the ENB pin is floating, the charger output and STATB pin
will turn off and the device will enter the monitor state
when a charge cycle is complete. If the battery voltage
falls below the re-charge threshold (VCV - VReQ) while in the
monitor state, the charger will automatically initiate a recharge cycle. The battery leakage current during monitor
state is no more than 1μA over temperature and typically
less than 0.1μA at room temperature.
While in the monitor state, the ENB tri-level input pin
remains fully active, and although in midrange, is sensitive
to both high and low levels. The SC820 can be forced from
the monitor state (no float-charging) directly to floatcharging operation by driving ENB low. This operation will
turn on the charger output, but will not assert the STATB
output. If the ENB pin is again allowed to float to midrange, the charger will remain on only until the output
current becomes less than the termination current, and
charging terminates. The SC820 turns off its charging
output and returns to the monitor state within a millisecond. This forced re-charge behavior is useful for
periodically testing the battery state-of-charge and
topping-off the battery, without float-charging and
without requiring the battery to discharge to the automatic re-charge voltage. ENB should be held low for at
least 1ms to ensure a successful forced re-charge.
Forced re-charge can be requested at any time during the
charge cycle, or even with no charging source present,
with no detrimental effect on charger operation. This
allows the host processor to schedule a forced re-charge
at any desired interval, without regard to whether a charge
cycle is already in progress, or even whether a charging
source is present. Forced re-charge will neither assert nor
release the STATB output.
Status Output
The STATB pin is an open-drain output. It is asserted
(driven low) as charging begins after a valid charging
source is connected and the voltage on either input is
between its selection and OVP limits. STATB is also
asserted as charging begins after the ENB input returns to
either of the enable voltage ranges (mid or low voltage)
from the disable range. STATB is subsequently released
when the termination current is reached to indicate endof-charge, when the ENB input is driven high to disable
charging, or when neither charging input is selected and
valid to charge. If the battery is already fully charged
when a charge cycle is initiated, STATB is asserted for
approximately 750μs before being released. The STATB
pin is not asserted for automatic re-charge cycles.
The STATB pin may be connected to an interrupt input to
notify a host controller of the charging status or it can be
used as an LED driver.
Logical CC-to-CV Transition
The SC820 differs from monolithic linear single cell Li-ion
chargers that implement a linear transition from CC to CV
regulation. The linear transition method uses two simultaneous feedback signals — output voltage and output
current — to the closed-loop controller. When the output
voltage is sufficiently below the CV regulation voltage, the
influence of the voltage feedback is negligible and the
15
SC820
Applications Information (continued)
output current is regulated to the desired current. As the
battery voltage approaches the CV regulation voltage
(4.2V), the voltage feedback signal begins to influence the
control loop, which causes the output current to decrease
although the output voltage has not reached 4.2V. The
output voltage limit dominates the controller when the
battery reaches 4.2V and eventually the controller is
entirely in CV regulation. The soft transition effectively
reduces the charge current below that which is permitted
for a portion of the charge cycle, which increases charge
time.
In the SC820, a logical transition is implemented from CC
to CV to recover the charge current lost due to the soft
transition. The controller regulates only current until the
output voltage exceeds the transition threshold voltage.
It then switches to CV regulation. The transition voltage
from CC to CV regulation is typically 5mV higher than the
CV regulation voltage, which provides a sharp and clean
transition free of chatter between regulation modes. The
difference between the transition voltage and the regulation voltage is termed the CC/CV overshoot. While in CV
regulation, the output current sense remains active. If the
output current exceeds by 5% the programmed fastcharge current, the controller reverts to current
regulation.
The logical transition from CC to CV results in the fastest
possible charging cycle that is compliant with the specified current and voltage limits of the Li-ion cell. The output
current is constant at the CC limit, then decreases abruptly
when the output voltage steps from the overshoot voltage
to the regulation voltage at the transition to CV control.
Thermal Limiting
Device thermal limiting is the third output constraint of
the Constant Current, Constant Voltage, “Constant”
Temperature (CC/CV/CT) control. This feature permits a
higher input OVP threshold, and thus the use of higher
voltage or poorly regulated adapters. If high input voltage
results in excessive power dissipation, the output current
is reduced to prevent overheating of the SC820. The
thermal limiting controller reduces the output current by
iT ≈ 50mA/ºC for any junction temperature TJ > T TL.
When thermal limiting is inactive,
TJ = TA + VΔ IFQ θJA,
where VΔ is the voltage difference between the VIN pin
and the BAT pin. However, if TJ computed this way exceeds
T TL, then thermal limiting will become active and the
thermal limiting regulation junction temperature will be
TJTL = TA + VΔ I(TJTL) θJA,
where
I(TJTL) = IFQ − iT (TJTL − T TL).
Combining these two equations and solving for TJTL, the
steady state junction temperature during active thermal
limiting is
TJTL
TA
V IFQ _ x iT TTL
1 V iT JA
JA
Although the thermal limiting controller is able to reduce
output current to zero, this does not happen in practice.
Output current is reduced to I(TJTL), reducing power dissipation such that die temperature equilibrium TJTL is
reached.
While thermal limiting is active, all charger functions
remain active and the charger logical state is preserved.
Operating a Charging Adapter in Current Limit
In high charging current applications, charger power dissipation can be greatly reduced by operating the charging
adapter in current limit. The SC820 VAD input supports
adapter-current-limited charging with a low deselection
falling threshold and with internal circuitry designed for
low input voltage operation. To operate an adapter in
current limit, RIPRGM is chosen such that the adapter input
programmed fast-charge current IFQ_AD exceeds the current
limit of the charging adapter IAD-LIM.
Note that if IAD-LIM is less than 20% of IFQ_AD, then the adapter
voltage can be pulled down to the battery voltage while
the battery voltage is below the pre-charge threshold. In
this case, care must be taken to ensure that the adapter
will maintain its current limit below 20% of IFQ_AD at least
until the battery voltage exceeds the pre-charge threshold. Failure to do so could permit charge current to exceed
16
SC820
Applications Information (continued)
the pre-charge current while the battery voltage is below
the pre-charge threshold. This is because the low input
voltage will also compress the pre-charge threshold internal reference voltage to below the battery voltage. This
will prematurely advance the charger logic from precharge current regulation to fast-charge regulation, and
the charge current will exceed the safe level recommended for pre-charge conditioning.
The low deselection falling threshold (VTADsel-F) permits the
adapter voltage to be pulled down to just above the
battery voltage by the charging load whenever the
adapter current limit is less than the programmed fastcharge current. The SC820 should be operated with
adapter voltage below the rising selection threshold
(VTADSel-R) only if the low input voltage is the result of
adapter current limiting. This implies that the VAD voltage
first exceeds VTADsel-R to begin charging, and is subsequently
pulled down to just above the battery voltage by the
charging load.
Interaction of Thermal Limiting and Current Limited
Adapter Charging
To permit the charge current to be limited by the adapter,
it is necessary that the adapter input fast-charge current
be programmed greater than the maximum adapter
current, (IAD-LIM). In this configuration, the CC regulator will
operate with its pass device fully on (in saturation, also
called “dropout”). The voltage drop from VAD to BAT is
determined by the product of the minimum RDS-ON of the
pass device multiplied by the adapter supply current.
In dropout, the power dissipation in the SC820 is
PILIM = (minimum RDS-ON) x (IAD-LIM)2. Since minimum RDS-ON
does not vary with battery voltage, dropout power dissipation is constant throughout the CC portion of the
charge cycle while the adapter remains in current limit.
The SC820 junction temperature will rise above ambient
by PILIM x θJA. If the device temperature rises to the temperature at which the thermal limiting control loop limits
charging current (rather than the current being limited by
the adapter), the input voltage will rise to the adapter
regulation voltage. The power dissipation will increase so
that the thermal limit regulation will further limit charge
current. This will keep the adapter in voltage regulation
for the remainder of the charge cycle.
To ensure that the adapter remains in current limit, the
internal device temperature must never rise to T TL. This
implies that θJA must be kept small enough to ensure that
TJ = TA + (PILIM × θJA) < T TL.
VUSB Under-Voltage Load Regulation
VUSB pin UVLR prevents the battery charging current from
overloading the USB Vbus network, regardless of the programmed fast-charge value. When the VUSB input is
selected, the SC820 monitors the input voltage (VVUSB) and
reduces the charge current as necessary to keep VVUSB at or
above the UVLR limit (VVUSB_UV_LIM). UVLR operates like a
fourth output constraint (along with CC, CV, and CT constraints), but it is active only when the VUSB input is
selected.
If the VUSB voltage is externally pulled below VUSB_UV_LIM
while the VAD input is absent, the UVLR feature will reduce
the charging current to zero. This condition will not be
interpreted as termination and will not result in an end-ofcharge indication. The STATB pin will remain asserted as if
charging is continuing. This prevents repetitive indications of end-of-charge alternating with start-of-charge in
the case that the external VUSB load is removed or is
intermittent.
Short Circuit Protection
The SC820 can tolerate a BAT pin short circuit to ground
indefinitely. The current into a ground short is approximately 10mA.
During charging, a short to ground applied to the active
current programming pin (IPRGM or IPUSB) is detected,
while a short to ground on the inactive programming pin
is ignored. Pin-short detection on an active current programming pin forces the SC820 into reset, turning off the
output. A pin-short on either programming pin will
prevent startup regardless of the charging input selected.
When the IPRGM or IPUSB pin-short condition is removed,
the charger begins normal operation automatically
without input power cycling.
Over-Current Protection
Over-current protection is provided in all modes of operation, including CV regulation. The output current is limited
to either the pre-charge or the fast-charge current (as
17
SC820
Applications Information (continued)
programmed by IPRGM or IPUSB, determined by input
selection), depending on the voltage at the output.
Input Over-Voltage Protection
The VAD and VUSB input pins are protected from overvoltage to at least 30V above GND. When the voltage of
the selected input exceeds the Over-Voltage Protection
(OVP) rising threshold (VTOVP-R), charging is halted. When
the input voltage falls below the OVP falling threshold
(VTOVP-F), charging resumes. Note that the VAD input
remains selected even in the case that the VAD voltage
exceeds the OVP threshold. An excessive VAD voltage will
disable charging despite the presence of a valid VUSB
voltage. An OVP fault turns off the STATB output. STATB is
turned on again when charging restarts.
The OVP threshold has been set relatively high to permit
the use of poorly regulated adapters. Such adapters may
output a high voltage until loaded by the charger. A
too-low OVP threshold could prevent the charger from
ever turning on and loading the adapter to a lower voltage.
If the adapter voltage remains high despite the charging
load, the fast thermal limiting feature will immediately
reduce the charging current to prevent overheating of the
SC820. This behavior is illustrated in Figure 4, in which VBAT
= 3.0V, IFQ = 700mA, and VVAD is stepped from 0V to 8.1V.
Initially, power dissipation in the SC820 is 3.6W.
VVAD=8.1V, VBAT=3.0V
IBAT=700mA (Initially), PDISSIPATION=3.6W (Initially)
IBAT (100mA/div)
ment. In this experiment, the final steady-state BAT
current was 462mA at TA = 25C on the SC820 evaluation
board. The fast thermal limiting feature ensures compliance with CCSA YD/T 1591-2006, Telecommunication
Industrial Standard of the People’s Republic of China —
Technical Requirements and Test Method of Charger and
Interface for Mobile Telecommunication Terminal, Section
4.2.3.1.
Operation Without a Battery
The SC820 can be operated as a 4.2V LDO regulator
without the battery present, for example, factory testing.
If this use is anticipated, the output capacitance C BAT
should be at least 2.2μF to ensure stability. To operate the
charger without a battery, the ENB pin must be driven low
or grounded.
Capacitor Selection
Low cost, low ESR ceramic capacitors such as the X5R and
X7R dielectric material types are recommended. The BAT
pin capacitor range is 1μF to 22μF. The VAD pin and VUSB
input capacitors are typically between 0.1μF and 2.2μF,
although larger values will not degrade performance.
Capacitance must be evaluated at the expected bias
voltage, rather than the zero-volt capacitance rating.
PCB Layout Considerations
Layout for linear devices is not as critical as for a switching
regulator. However, careful attention to detail will ensure
reliable operation.
•
VVAD (2V/div)
•
VBAT (2V/div)
•
VVAD ,VBAT=0V—
IBAT=0mA—
1s/div
Figure 4 — Thermal Limiting Example
Notice the BAT output current is rapidly reduced to limit
the internal die temperature, then continues to decline as
the circuit board gradually heats up, further reducing the
conduction of heat from the die to the ambient environ-
Place input and output capacitors close to the
device for optimal transient response and device
behavior.
Connect all ground connections directly to the
ground plane. If there is no ground plane,
connect to a common local ground point before
connecting to board ground near the GND pin.
Attaching the part to a larger copper footprint
will enable better heat transfer from the device,
especially on PCBs with internal ground and
power planes.
Design Considerations — USB Charging
The USB specification restricts the load on the USB Vbus
power network to 100mA for low power devices and for
18
SC820
Applications Information (continued)
high power devices prior to granting permission for high
power operation. The specification restricts the Vbus load
to 500mA for high power devices after granting permission to operate as a high power device. This suggests that
a fixed 1:5 ratio of low power to high power charging
current is desirable. But this can result in suboptimal
charging when the battery capacity is too small to permit
fast charging at 500mA. For example, a 250mAh battery
will typically require a fast-charge current of 250mA or
less. A fixed 1:5 ratio for USB low and high power charging
will unnecessarily reduce charging current to 50mA, well
below the 100mA permitted.
An arbitrary ratio of USB low-to-high power charging currents can be obtained using an external n-channel FET
operated with a processor GPIO signal to engage a second
parallel IPUSB resistor. The external circuit is illustrated in
Figure 5.
IPUSB
5
RIPUSB_HI
USB Hi/Lo
Power Select
RIPUSB
Figure 5 — External programming of arbitrary USB
high power and low power charge currents.
For USB low power mode charging, the external transistor
is turned off. The transistor is turned on when high power
mode is desired. The effect of the switched parallel IPUSB
resistor is to reduce the effective programming resistance
and thus raise the fast-charge current.
An open-drain GPIO can be used directly to engage the
parallel resistor RIPUSB_HI. Care must be taken to ensure that
the RDS-ON of the GPIO is considered in the selection of
RIPUSB_HI. Also important is the part-to-part and temperature variation of the GPIO RDS-ON, and their contribution to
the USB High Power charge current tolerance. Note also
that IPUSB will be pulled up briefly to as high as 3V during
startup to check for an IPUSB static pinshort to ground. A
small amount of current could, potentially, flow from
IPUSB into the GPIO ESD structure through RIPUSB_HI during
this event. While unlikely to do any harm, this effect must
also be considered.
For purposes of design for dual-input adapter/USB charging, a small battery is one with a desired fast-charge
current less than 500mA. A 300mAh battery with
maximum fast-charge current of 300mA is an example.
The adapter input and USB input high power fast-charge
currents should both be set to 300mA max. The USB input
low power fast-charge current is 100mA max. Refer to the
circuit of Figure 4 and the data of Figures 1a and 1b. For
IFQ_AD = 300mA max, use RIPRGM = 7.50kΩ. The fixed IPUSB
resistor of RIPUSB = 23.2kΩ programs IFQ_USB = 100mA max.
When parallel resistor RIPUSB_HI = 11.0kΩ is switched in, the
equivalent IPUSB resistor is 7.50kΩ, and so IFQ_USB = 300mA
max.
A large battery is any battery with a desired fast-charge
current exceeding 500mA. Large battery charging is most
consistent with the USB fixed 1:5 current ratio low-to-high
power model of operation. For example, consider an
800mAh battery, with maximum fast-charge current of
800mA. The adapter input fast-charge should be configured for 800mA max (RIPRGM = 2.80kΩ), the USB low power
fast-charge set to 100mA max (RIPUSB = 23.2kΩ), and the
USB high power fast- charge set to 500mA max
(RIPUSB_HI = 5.62kΩ).
USB Low Power Mode Alternative
Where a USB mode selection signal is not available, or
where system cost or board space make USB low power
mode external current programming impractical, USB low
power charging can be supported indirectly. The IPUSB
pin resistance can be selected to obtain the desired USB
high power charge current. The VUSB pin UVLR feature
ensures that the charging load will never pull the USB
Vbus supply voltage below VUSB_UV_LIM regardless of the USB
host or hub supply limit. The UVLR limit voltage guarantees that the voltage of the USB Vbus supply will not be
loaded below the low power voltage specification limit, as
seen by any other low power devices connected to the
same USB host or hub.
19
SC820
Outline Drawing — MLPD-UT8 2x2
B
D
A
DIM
E
PIN 1
INDICATOR
(LASER MARK)
A
SEATING
PLANE
aaa C
A2
A1
C
A
A1
A2
b
D
D1
E
E1
e
L
N
aaa
bbb
DIMENSIONS
INCHES
MILLIMETERS
MIN NOM MAX MIN NOM MAX
.020
.024 0.50
0.60
.000
.002 0.00
0.05
(.006)
(0.1524)
.007 .010 .012 0.18 0.25 0.30
.075 .079 .083 1.90 2.00 2.10
.061 .067 .071 1.55 1.70 1.80
.075 .079 .083 1.90 2.00 2.10
.026 .031 .035 0.65 0.80 0.90
.020 BSC
0.50 BSC
.012 .014 .016 0.30 0.35 0.40
8
8
.003
0.08
.004
0.10
D1
1
2
LxN
E/2
E1
N
bxN
bbb
e
C A B
e/2
D/2
NOTES:
1.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS.
20
SC820
Land Pattern — MLPD-UT8 2x2
H
DIMENSIONS
R
(C)
K
G
Z
Y
P
DIM
INCHES
MILLIMETERS
C
(.077)
(1.95)
G
.047
1.20
H
.067
1.70
K
.031
0.80
P
.020
0.50
R
.006
0.15
X
.012
0.30
Y
.030
0.75
Z
.106
2.70
X
NOTES:
1.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2.
THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
3.
THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD
SHALL BE CONNECTED TO A SYSTEM GROUND PLANE.
FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR
FUNCTIONAL PERFORMANCE OF THE DEVICE.
Contact Information
Semtech Corporation
Power Management Products Division
200 Flynn Road, Camarillo, CA 93012
Phone: (805) 498-2111 Fax: (805) 498-3804
www.semtech.com
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