SC804A [SEMTECH]
Fully Integrated 4.4V Lithium-Ion Battery Charger System with Timer; 完全集成的4.4V锂离子电池充电器系统具有定时器型号: | SC804A |
厂家: | SEMTECH CORPORATION |
描述: | Fully Integrated 4.4V Lithium-Ion Battery Charger System with Timer |
文件: | 总21页 (文件大小:539K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
SC804A
Fully Integrated 4.4V Lithium-Ion
Battery Charger System with Timer
POWER MANAGEMENT
Description
Features
ꢀFully integrated charger with FET pass transistor,
reverse-blocking diode, sense resistor, timer, and
thermal protection
The SC804A is a fully integrated full-feature, single cell
constant-current/constant-voltage (CC/CV) 4.4V Lithium-
Ion battery charger. With an integrated timer and
complete charge control algorithm, the SC804A is ideal for
stand-alone charger applications. The SC804A contains
programmable pre-charge, fast-charge and termination
current settings. The SC804A can be programmed to
terminate charging based on the output current or the
time-out of the programmable timer. The fast charge
current is typically set with an external resistor, but it can
also be adjusted by applying an analog voltage to the AFC
pin. This feature allows use of a microcontroller to set
charging current via a DAC output.
ꢀBattery voltage controlled to 1% accuracy
ꢀProgrammable precharge, fastcharge & termination
current over wide range, with analog current control
reference input for design flexibility
ꢀUp to 1.5A continuous charge current
ꢀInput voltage range from 3V to 14V
ꢀSoft-start reduces start-of-charge adapter
load transients
ꢀNTC thermistor sense input and adjustable cold
temperature threshold
The SC804A’s 14V input voltage range eliminates the
need for additional protection circuitry required by other
ꢀAdjustable 2 - 6 hour programmable charge timer
5V chargers to protect against faulty adapters. The ꢀ0.1μA battery drain current in shutdown and monitor
SC804A also incorporates an under-voltage lockout falling
threshold of 3V so that charging will continue if the input
supply goes into a current-limited mode.
modes
ꢀSmall 4mm x 4mm 16 lead MLPQ package
ꢀOver-current protection in all modes
ꢀOver-voltage protection
Reference ground and battery sense inputs are provided
to eliminate voltage drops during charging due to high
charging currents.
ꢀRemote Kelvin sensing at the battery terminals
ꢀStatus indicators for charger-present, charger-active,
over-voltage fault, and error notification
The output voltage to the battery is controlled to within
1% of the programmed voltage. The SC804A can also
Applications
ꢀCellular phones
ꢀPDAs
ꢀHandheld meters
ꢀCharging stations
function as a general purpose current source or as a
ꢀHandheld computers
ꢀDigital cameras
ꢀProgrammable current
source
Typical Application Circuit
current source for charging nickel-cadmium (NiCd) and
nickel-metal-hydride (NiMH) batteries.
Typical Application Circuit
Charger VIN
14
11
VCC
13
CPB
10
12
2
OV_FLT
OVPB
IPRGM
NTC
CHRGB
RTIM
CTO
Red
Green
3
7
4
8
6
5
R3
C1
2.2 μF
1
ITERM
FLTB
BSEN
VOUT
VOUT
AFC
RT
NTC
16
15
9
R5
R6
R1
R2
GND
C2
RGND
2.2μF
Battery
SC804A
R4
ERROR
DAC ISET
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SC804A
POWER MANAGEMENT
Absolute Maximum Ratings
Exceeding the specifications below may result in permanent damage to the device or device malfunction. Operation outside of the parameters specified in the
DRAFT
Electrical Characteristics section is not implied.
Parameter
Symbol
Maximum
Units
VCC, CTO, NTC to GND
-0.3 to 14.0
V
VOUT, BSEN, RTIM, AFC, IPRGM, CPB, CHRGB, OVPB,
ITERM, FLTB, to GND
-0.3 to +6.0
V
RGND to GND
-0.3 to 0.3
V
A
VOUT Output Current
IVOUT
Pd
1.5
Power Dissipation MLP (Derate 20mW/°C above 85°C)
Thermal Impedance, Junction to Ambient(1)
Junction Temperature
2
48
W
θJA
°C/W
°C
TJ
150
Operating Ambient Temperature Range
IR Reflow Temperature
TA
-40 to +85
260
°C
TLEAD
TSTG
°C
Storage Temperature Range
VOUT short to GND
-65 to 150
Continuous
2
°C
ESD Protection Level(2)
VESD
kV
Notes:
1) Calculated from package in still air, mounted to 3” x 4.5”, 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards.
2) Tested according to JEDEC standard JESD22-A11 4-B.
Electrical Characteristics
Unless otherwise noted: VCC = 4.75V - 5.25V. Typical values are at TA = 25°C Min and Max are for -40°C < TA < +85°C unless noted.
Parameter
Symbol
Conditions
Min
Typ
Max
Units
Operating Voltage
VCCOP
4.28
5.0
6.22(1)
V
Charging begins when
threshold is exceeded
VCC UVLO Rising Threshold
VCC UVLO Falling Threshold
VTUVLOR
VTUVLOF
VTOVPR
3.88
2.86
6.63
4.08
3.06
6.94
4.28
3.26
7.40
V
V
V
Charging continues until
threshold is reached
VCC OVP
Rising Threshold
VCC OVP
Falling Threshold
VTOVPF
VTOVPH
ICCDIS
6.22
200
6.63
350
1.9
7.00
600
V
VCC OVP Hysteresis
Operating Current
mV
Shutdown Mode - CHRGB, CPB,
OVPB, FLTB off NTC = 0V
mA
Charging Mode - CHRGB, CPB,
OVPB, FLTB off NTC = 2.5V
ICCCHG
2.0
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SC804A
DRAFT
POWER MANAGEMENT
Electrical Characteristics (Cont.)
Parameter
Symbol
Conditions
Min
Typ
Max
Units
Battery Leakage Current
(VOUT and BSEN)
VCC = 0V,
VOUT = BSEN = 4.5V
ILEAKBAT
0.1
2
μA
Regulated Constant
Voltage
VCV
0°C ≤ TJ ≤ 125°C
4.314
22
4.357
30
4.40
38
V
RGND Output Accuracy
VOUT = VOUTNOM + ∆RGND
VRGND
RGND - GND = 30mV
mV
RGND Current
IRGND
IPREQ
ITERM
RGND = 0V
35
μA
Battery Pre-Charge Current
RITERM = 499Ω, 0°C ≤ TJ ≤ 125°C
270
270
300
330
330
mA
Battery Termination
Current
RITERM = 499Ω, 0°C ≤ TJ ≤ 125°C
300
815
405
1
mA
mA
mA
V
Battery Fast-Charge
Current
RPRGM = 1.87kΩ, VOUT = 3.8V
0°C ≤ TJ ≤ 125°C
IFAST
753
364
878
447
AFC DAC
Fast-Charge Current
RPRGM = 1.87kΩ, V(AFC) = 0.75V
0°C ≤ TJ ≤ 125°C
IDACADJ
VTAFC
VITERM
VIPRGM
VTPreQ
VTReQ
TOT
AFC Enable/Disable
Threshold
VCC - VAFC > VTAFC disables
Analog Fast Charge
ITERM Regulated
Voltage
1.45
1.45
2.9
1.557
1.557
3.01
100
150
1.66
1.66
3.11
140
V
IPROG Regulated
Voltage
V
VBAT Precharge
Threshold
0°C ≤ TJ ≤ 125°C
VCV - VBSEN, 0°C ≤ TA ≤ 85°C
Hysteresis = 10°C
V
VBAT Recharge
Threshold
60
mV
°C
Over-Temperature
Shutdown
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SC804A
DRAFT
POWER MANAGEMENT
Electrical Characteristics (Cont.)
Parameter
Symbol
Conditions
Min
Typ
Max
Units
VTNTCDIS
SC804A Disabled
0.3
0.6
0.8
V
NTC Hot VTH
Applies to falling threshold
4.3V ≤ VCC ≤ 6.5V
29
30
31
% of
VCC
VTNTCH
1.45
73.4
1.50
74.4
1.55
75.4
V
at VCC = 5V
NTC Cold VTH, VCTO = 0V
Applies to rising threshold
4.3V ≤ VCC ≤ 6.5V
% of
VCC
VTNTCC
3.67
3.72
50
3.77
V
at VCC = 5V
NTC Hot & Cold VTNTCx
hysteresis
(VTNTCx Rising - VTNTCx Falling)
NTC Thresholds
VTNTCHYS
mV
Applies to internal NTC thresholds
CTO Voltage (Adjustable NTC
Cold Rising Threshold) Setting
Range(2), -40°C ≤ TA ≤ 25°C(NTC
Cold Rising Threshold is VTNTCC
when CTO tied to GND)
% of
VCC
50
90
70
VCTO
Threshold Error(3),
-40°C ≤ TA ≤ 25°C
-70
mV
mV
Internal hysteresis on CTO
(VCTO Rising - VCTO Falling)
Applies to externally set
NTC cold threshold
VTCTOHYS
50
3.5V ≤ VOUT ≤ VCC - 150mV
0°C ≤ TJ ≤ 125°C
Adjust Mode BSEN Voltage
VBSEN-ADJ
3.189
3.217
3.253
400
V
Adjust Mode Enable Voltage,
VOUT-BSEN
VADJEN
VADJDIS
VRTIM
3.5V ≤ VOUT ≤ VCC - 150mV
3.5V ≤ VOUT ≤ VCC - 150mV
RRTIM = 37.4kΩ
mV
mV
V
Adjust Mode Disable
Voltage, VOUT-BSEN
150
1.450
0.65
External RTIM
Regulation Voltage
1.557
0.85
1.1
1.660
VRTIM ≤ VTTIMER
Timer Disable
Threshold
VTTIMER
VTINTTS
V
disables internal timer
VCC-VRTIM > VTINTTS
selects internal timer
Internal Timer Select
V
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SC804A
DRAFT
POWER MANAGEMENT
Electrical Characteristics (Cont.)
Parameter
Symbol
Conditions
Min
Typ
Max
Units
Pre-Charge Fault
Time-out
RRTIM = 37.4kΩ
RTIM pulled to VCC
-20%
-35%
51
44
+20%
+35%
TPreQF
min
Complete Charge
Time-out
RRTIM = 37.4kΩ
RTIM pulled to VCC
-20%
-35%
3.37
2.89
+20%
+35%
TQCOMP
hr
CHRGB On
CHRGB Off
CPB On
VCHRGB
ICHRGB
VCPB
Load = 5mA
Leakage Current, V = 5V
Load = 5mA
0.5
0.5
0.5
0.5
1
1
1
1
1
1
1
1
V
μA
V
CPB Off
ICPB
Leakage Current, V = 5V
Load = 5mA
μA
V
OVPB On
OVPB Off
FLTB On
VOVPB
IOVPB
VFLTB
IFLTB
Leakage Current, V = 5V
Load = 5mA
μA
V
FLTB Off
Leakage Current, V = 5V
μA
Notes:
1) VCC_OP Max is the “Maximum Vsupply” as defined in EIA/JEDEC Standard No. 78, paragraph 2.11.
2) The absolute voltage on CTO must not exceed 6.0V to ensure normal operation.
3) The threshold error is tested at VCTO min and max only.
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SC804A
POWER MANAGEMENT
Ordering Information
Pin Configuration
DRAFT
DEVICE
PACKAGE
16
15
14
13
SC804AMLTRT(1)
MLPQ -16(2)
RTIM
BSEN
CTO
1
2
3
4
12
11
10
9
TOP VIEW
CPB
SC804EVB
Evaluation Board2(
)
CHRGB
IPRGM
ITERM
Notes:
T
AFC
1) Available in tape and reel packaging only. A reel contains 3000
devices.
5
6
7
8
2) Available in lead-free packaging only. This product is fully WEEE
and RoHS compliant.
MLPQ16: 4X4 16 LEAD
Pin Descriptions
Pin #
Pin Name
Pin Function
Battery voltage sense. Connect to battery positive terminal for Kelvin voltage sensing, VOUT otherwise.
Do not leave open.
1
BSEN
Cold Temperature Offset. Adjustable NTC input high voltage (cold temperature) threshold. When the pin
2
CTO
is connected to GND the NTC high voltage threshold defaults to VTNTCC×VVCC
.
3
4
5
6
IPRGM
ITERM
RGND
GND
Charger current program pin for fast-charge mode. Requires a resistor to GND to program fast-charge current.
Charger termination current program pin. Requires a resistor to GND to program pre-charge and termination current.
Reference ground. Connect to battery’s negative terminal for Kelvin voltage sensing, GND otherwise. Do not leave open.
Ground.
Input for battery NTC thermistor network. Voltage between VTNTCH×VVCC, normally the hot threshold, and the CTO voltage
(VTNTCC×VVCC if CTO is tied to GND), normally the cold threshold, enables charging. Voltages outside this range suspend
charging and drive FLTB pin active (low). Voltage below VTNTCDIS (nominally 0.6V) disables the SC804A and resets the
charge timer (with FLTB pin inactive).
7
NTC
8
9
FLTB
AFC
Open drain fault indicator. Active low when a fault condition occurs.
Analog Fast Charge input. Connect to a DAC for analog control of fast charge current level, connect to VCC
to disable this feature. Do not leave open.
Open drain charge status indicator. Active low when the charger is on and the output current exceeds the
termination current setting, high impedance when IVOUT < ITERM.
10
11
CHRGB
CPB
Open drain charger-present indicator. Active low when VCC exceeds UVLO.
Programmable timer input pin. Connect to VCC to select the default time-out of 3 hrs., connect to GND
to disable timer, or connect an external resistor to GND to program the time-out period.
12
RTIM
13
14
15
16
OVPB
VCC
Open drain over-voltage indicator. Active low when an input over-voltage fault occurs.
Input supply pin. Connect to adapter power.
VOUT
VOUT
Charger output. Connect to battery.
Charger output. Connect to battery.
THERMAL
PAD
Thermal-conduction pad on bottom of the package. Solder directly to the ground plane with multiple
thermal vias to all other ground planes.
T
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SC804A
DRAFT
POWER MANAGEMENT
Block Diagram
14
VCC
1
9
BSEN
AFC
V
CV (VBSEN-ADJ in Adj. Mode)
Reference
Voltages
Fast-Charge Ref
Pre- Charge Ref
VTNTCC VTNTCH
5
RGND
Pre-Charge On
Fast-Charge On
Over-Temp
Under-Voltage
Over-Voltage
Cold
Threshold
VOUT
VOUT
15
16
2
6
7
CTO
GND
NTC
Offset
Control
Timer
V
ITERM
NTC
Interface
ITERM
IPRGM
4
3
RTIM 12
V
IPRGM
10
11
8
CHRGB
CPB
FLTB
OVPB
13
Figure 1 - SC804A Functional Block Diagram
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SC804A
DRAFT
POWER MANAGEMENT
Applications Information
General Operation
Fast-Charge Mode (CC)
The SC804A can be configured independently with respect The fast-charge CC (Constant Current) mode is active when
to fast-charge and termination current, output voltage, the battery voltage is above VTPreQ and less than VCV. The
and timing, depending on the application. A typical fast-charge current can be set to a maximum of 1.5A and
charging cycle is described below. Details on alternative is selected by the program resistor on the IPRGM pin. The
applications and output programmability are covered in voltage on this pin will represent the current through the
the individual sections.
battery, enabling a microprocessor via an analog-to-digital
converter (ADC) to monitor battery current by sensing the
voltage on the IPRGM pin. The equation to set the fast-
charge current is given by:
The charging cycle begins when the power adapter is
connected to the device. The SC804A performs glitch
filtering on the VCC input and initiates a charge cycle
when VVCC is greater than the under-voltage lockout (UVLO)
rising threshold voltage. If the battery voltage is less than
the pre-charge threshold level, the SC804A will output the
pre-charge current. Once the pre-charge threshold voltage
is exceeded, the SC804A enters fast-charge constant
current (CC) mode. When the battery voltage reaches its
final value, the charger enters the constant voltage (CV)
mode. In this mode the output current decreases as the
battery continues to charge until the termination current
level is reached. The CHRGB output turns off when IOUT
drops below the termination current. If the charge timer
is active, the SC804A continues to hold the battery in
CV charge mode until the timer expires. When the timer
expires the charger enters the monitor mode where the
output remains off until the voltage at VOUT drops by
VTReQ. At this point a new charge cycle is initiated.
VIPRGM_Typ
× 1000
FCI =
RIPRGM
The superior fast-charge current accuracy of the SC804A
is obtained by use of a patented* polarity-switched
(i.e., chopped) current sense amplifier to nullify current
measurement offset errors.
Compliance with the absolute maximum output current
I
VOUTMAX, allowing for current regulation tolerance, requires
that RIPRGM be no smaller than 1.05kΩ nominal. RIPRGM can
be as large as 12.1kΩ, for a nominal FCI as small as 130
mA, but must exceed PCI by at least 80mA. Note that for
a given program resistor the current into the battery in CV
mode can be determined by replacing VIPRGM_Typ with the
actual voltage on the IPRGM pin in the above equation.
The CC current can also be modified by applying an analog
voltage to the AFC pin as described below.
Pre-Charge Mode
Pre-charge mode is automatically enabled whenever
the battery voltage is below the pre-charge threshold
voltage, VTPreQ. It is used to limit the power dissipation and
precondition the battery for fast charging. The pre-charge
current value is determined by the resistor on the ITERM
pin. The pre-charge current is programmable from 50mA
to 350mA. The equation to select the pre-charge current
is given by:
Analog Fast Charge (AFC Pin)
Many applications require more than one current setting
for fast-charge. This behavior is obtained in the SC804A
using the AFC function. When the AFC pin is connected
to VCC the device behaves as described in the previous
section. When the AFC pin is driven by an analog voltage
between 0V and (VVCC-1.0)V, the SC804A automatically
uses this pin voltage to set the maximum fast-charge
current according to the following equation:
VITERM_Typ
PCI =
× 100
RITERM
whereVITERM_Typ designatesthetypicalvalueofVITERM. When
the timer is enabled there is also a maximum allowed pre-
charge duration. If the pre-charge time exceeds 25% of
the total charge cycle the charger will turn off due to a
pre-charge fault. This fault is cleared when VCC is toggled
VAFC
FCI =
× 1000
RIPRGM
This adjustment to the fast charge current is obtained
or the output voltage rises above VTPreQ
.
by replacing the fixed VIPRGM reference voltage with the
*US Patent 6,836,095.
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SC804A
POWER MANAGEMENT
Applications Information (Cont.)
AFC voltage. (Note that AFC voltages above V
produce IVOUT exceeding that programmed as per the Fast- capacity. The RTIM pin is connected to VCC to select the
Charge Mode (CC) section.) For any applied AFC voltage, internal timer, and to GND to disable the timer.
in the event of a faulty battery and to maximize DchRarAgFinTg
will
IPRGM
FCI must not drop below 130mA, and FCI must always
remain at least 80mA greater than PCI.
Connecting a resistor between RTIM and GND will program
the total charge time according to the following equation:
RRTIM
————
3.08
1
× ———
3600
Termination Current
Charge time =
(
)
Once the battery voltage reaches VCV the SC804A will
transition from constant current mode to constant voltage
mode. The current through the battery will decrease while
the voltage remains constant as the battery becomes fully
charged. When the current falls below the programmed
termination current set by the termination resistor
connected to the ITERM pin, the SC804A will disable
CHRGB. If the timer is enabled the output will continue
to float-charge in CV mode until the timer expires. If the
timer is disabled, the output will turn off as soon as the
termination current level is reached. The equation to set
the termination current is given by:
With charge time expressed in hours. The timer is
programmable over the range of 2 to 6 hours. The internal
timer selection results in a charge time of 3 hours. The
SC804A will automatically turn off the output when the
charge timer times out.
NTC Interface
The NTC pin provides an interface to a battery pack
Negative Temperature Coefficient (NTC) thermistor. The
typical NTC network has a fixed resistor from VCC to the
NTC pin, and the battery pack NTC thermistor connected
from the NTC pin to ground. In this configuration, an
increasing battery temperature produces a decreasing
NTC pin voltage, and a decreasing battery temperature
produces an increasing NTC pin voltage.
VITERM_Typ
ITERM =
× 100
RITERM
ITERM can be programmed to be as high as 300mA or as
low as 50mA, though accuracy is not guaranteed below
100mA. ITERM must be programmed to be less than FCI
for correct operation of the charge cycle.
This configuration is shown in the typical application
schematic on page 1 of this datasheet. When the NTC
voltage from the divider is greater than the high (cold)
threshold or less than the low (hot) threshold, the SC804A
suspendsthechargecyclebyturningofftheoutput, halting
(but not resetting) the charge timer, and indicating a fault
on the FLTB pin. Hysteresis is included for both high and
low NTC thresholds to avoid chatter at the NTC trip points.
When the NTC pin voltage returns to the valid range, the
SC804A automatically resumes the charge cycle. The
charge timer will time-out when the SC804A output on-
time exceeds the timer setting regardless of how long it
has been disabled due to the NTC temperature.
Monitor Mode
When a charge cycle is complete, the SC804A output
turns off and the device enters monitor mode. If the
voltage of the battery falls below the recharge threshold
(VCV - VReQ), the charger will clear the charge timer and
re-initiate a charge cycle. The maximum current drain of
the battery during monitor mode will be no more than 1μA
over temperature. The status of the charger output as a
function of the timer and IOUT is tabulated below.
An input voltage between VTNTCH×VVCC and the CTO input
voltage VCTO (VTNTCC×V if CTO is tied to GND) enables
charging. An input voVltCaC ge outside this range suspends
charging and drives FLTB pin active (low). The internal
NTC thresholds of VTNTCH and VTNTCC were designed to
work with standard thermistors available from numerous
vendors.
Timer
Iout
N/A
Output State
T < Timeout
T > Timeout
Disabled
On
Off
Off
N/A
< Itermination
Charge Timer
NTC pin voltage below VTNTCDIS (nominally 0.6V) disables
The timer on the SC804A has two functions: to protect
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SC804A
POWER MANAGEMENT
Applications Information (Cont.)
DRAFT
the SC804A and resets the charge timer (with the FLTB or R3 = 2.333×RHOT = 13.624kΩ exactly. The closest 1%
pin inactive). The NTC pin can be pulled down to ground standard nominal value is R3 = 13.7kΩ.
by an external n-channel FET transistor or processor GPIO
Step 2: Verify acceptable thermistor self heating. In
general, lower values of RT provide more noise immunity
for the NTC voltage, but at the expense of bias current
from the input adapter and power dissipation in the NTC
network. The dissipation constant is the power rating of
the thermistor resulting in a 1oC self heating error. The
greatest self-heating occurs at low thermistor resistance
(at high temperature). Since temperature sensing
accuracy matters only at the charging temperature range
thresholds, self heating is assessed only at the worst case
high temperature threshold of +40oC.
to disable or reset the SC804A.
Note that the response of the SC804A to NTC pin voltage
above the high threshold and below the low threshold
is the same. Thus it is possible to configure the NTC
network with the battery pack thermistor between NTC
and VCC, and a fixed resistor between NTC and ground.
This configuration may be useful if it is desired to reset the
charge timer (and the CHRGB output) when the battery
pack is removed (so the fixed resistor pulls the NTC pin to
ground) while VCC is present.
For VVCC = 5V, the 40oC NTC network current INTC_HOT
=
VVCC (R3 + RHOT) = 0.246mA. Power dissipation in the
Cold Temperature Offset (CTO)
/
thermistor at this temperature, PHOT = RHOT × (INTC_HOT)2 =
0.38mW, for self heating of approximately 0.13oC. The
actual high temperature threshold will thus be lower by
0.13oC. This self-heating error is usually acceptable. If
it is not, then a thermistor with a greater RHOT must be
chosen.
The voltage applied to the CTO pin sets the NTC high
voltage (normally the cold temperature threshold) for the
NTC input. The default NTC high threshold (VTNTCC×VVCC
can be selected by connecting the CTO pin to ground. If
it is desired to change this threshold, the voltage on the
CTO pin can be set between 0.5×VVCC and 0.9×VVCC
)
.
Step 3: Determine the desired high (cold) threshold.
Compute the NTC network resistor divider voltage, as a
function of VVCC, at the cold temperature threshold.
This feature is especially useful if a single PCB design
is needed to satisfy similar applications with different
requirements. The temperature range for normal charging
can be adjusted by adjusting resistor values on a divider
network without changing the NTC thermistor, which
is often enclosed in the battery pack. An example of a
typical application is shown in Figure 2.
VCC × RCOLD
NTCCOLD
=
= 0.6591 × VCC
R3 + RCOLD
Step 4: Configure CTO. If NTCCOLD is sufficiently close
to the default cold threshold (VTNTCC×VVCC), then simply
connect CTO to ground, disabling the CTO function, to
complete the design. But in this example it is not, so the
voltage on CTO must be set to 0.6591×VVCC. The simple
resistive voltage divider network of Figure 2 can be used
to obtain the desired CTO voltage.
NTC/CTO Design Example
The following example assumes the NTC network
configurationofFigure2, withafixedresistorR3connected
between NTC and VCC, and a battery NTC thermistor
RT connected between NTC and ground. The battery
temperature range over which charging is permitted is
0oC through 40oC. The datasheet for the selected NTC
thermistor indicates that RT = 5.839kΩ at 40oC, at RT =
26.49kΩ at 0oC, with a dissipation constant DC = 3mW.
Designate RHOT = 5.839kΩ and RCOLD = 26.49kΩ.
VCTO = NTCCOLD
VCC × RCT2
= 0.6591 × VCC =
RCT1 + RCT2
or
Step 1: Select R3. For the normal (NTC thermistor to
ground) configuration, solve the NTC network voltage
divider for R3 to place the NTC voltage at 0.3×VCC when
RCT1
1 0.6591
=
= 0.5172
RT = RHOT
.
RCT2
0.6591
VCC × RHOT
R3 + RHOT
0.3 × VCC =
© 2005 Semtech Corp.
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SC804A
POWER MANAGEMENT
Applications Information (Cont.)
The choice of RCT1 and RCT2 is somewhat arbitrary. The
internal voltage references as VOUT pulls VCC DdoRwAnFtTo
simplest approach is to pick one and compute the other. near, or below, VCV, creating a reduced output regulation
A good choice here is RCT1 = 115kΩ, and RCT2 = 221kΩ, as voltage approximately 200mV below VCC. Thus VCC
these standard 1% tolerance values produce the closest cannot be pulled down below VOUT + 200mV. The dropout
match to the desired voltage divider ratio. With these voltage will be larger than 200mV whenever the minimum
resistor nominal values,
path resistance multiplied by the output current exceeds
200mV, but it cannot be smaller than 200mV.
VCC × RCT2
VCTO
=
= 0.6577 × VCC
This greatest-of-two-limit dropout voltage behavior is
evident in the dropout voltage typical performance plot.
R
CT1 + RCT2
When operating in Adjust Mode (next section), the
regulated minimum dropout voltage depends on the
programmed VOUT regulation voltage, and dropout also
varies with the actual output voltage during CC charging.
See Figure 4 for an illustration of dropout voltage data.
which is, nominally, only 0.2% below the target value of
0.6591×VVCC. The CTO network will present a load of only
15μA to a 5V charging adapter. The nominal impedance
presented to the CTO pin is RCT1 || RCT2 = 75.6kΩ. Any
impedance on the order of 100kΩ (or less) is acceptable.
Adjust Mode
Remote Kelvin Sensing at the Battery
The SC804A can be configured for an output voltage
other than VCV using Adjust (ADJ) Mode. In Adjust Mode
the output voltage is determined by an external resistor
divider from VOUT to BSEN. When BSEN is connected in
this fashion, VVOUT (during Constant Voltage (CV) charging)
will be controlled such that the voltage at the BSEN pin
The BSEN pin provides the positive Kelvin sensing voltage
feedback to the CV amplifier and should be connected as
close to the battery + terminal as possible. Likewise, the
RGND pin should be connected directly to the negative
terminal of the battery. This allows the designer great
flexibility in PCB layout and achieves greater accuracy
by sensing the battery voltage directly at the battery
terminals. When laying out the PCB, the designer should
route the BSEN and RGND trace directly to the battery
connection terminals, rather than just to the VOUT and
GND pins on the device.
(VBSEN) is the reference voltage VBSEN-ADJ
.
The output voltage can be set to any voltage desired by
an appropriate choice of divider network resistors, within
the following limits. When the SC804A is programmed for
adjust mode, VVOUT is required to be 150mV less than VVCC
,
and VVOUT is required to be 400mV greater than VBSEN
.
VVOUT within 150mV of VBSEN guarantees normal mode
operation. This implies that, for BSEN used as a Kelvin
sense of battery voltage, the product of the fast charge
current and the charge path resistance from VOUT to the
Kelvin sense point should not exceed 150mV to ensure
normal mode operation.
Dropout Voltage
Dropout voltage is the smallest achievable difference
voltage between VCC and VOUT under a particular
operating condition. Dropout voltage is encountered
during CC charging whenever the current limit of the
charging adapter is less than the SC804A FCI programmed
current. In this case, the adapter voltage (the SC804A
input voltage) will be pulled down to the battery voltage
(the SC804A output voltage) plus the dropout voltage.
The SC804A Adjust Mode schematic is shown in Figures
3a and 3b. Referring to these schematics, the equation
for setting the output voltage is:
R11
R12
Dropout voltage is the larger of two values: (1) the I-R
component, which is the output current multiplied by the
minimum VCC-to-VOUT path resistance (which is highly
temperature dependent), and (2) a regulated minimum
difference voltage, which is output voltage dependent
but is independent of the output current. The regulated
minimum dropout voltage results from the collapse of
VOUT = VBSEN-ADJ_TYP x ( 1 +
)
The capacitor C3 across R8 in the feedback network
introduces zero-pole frequency compensation for stability.
Place the zero according to the following equation to
ensure stability:
1
R11 × C3 =
2ꢀ × 100kHz
© 2005 Semtech Corp.
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SC804A
DRAFT
POWER MANAGEMENT
Applications Information (Cont.)
Charger VIN
14
13
3
11
10
12
2
VCC
CPB
CHRGB
RTIM
CTO
OV_FLT
OVP
Red
Green
R3
IPRGM
NTC
C1
2.2 μF
7
RCT1
RCT2
4
1
ITERM
FLTB
GND
BSEN
VOUT
VOUT
AFC
RT
NTC
8
16
15
9
R5
R6
6
R1
R2
5
RGND
SC804A
C2
R4
2.2μF
ERROR
Figure 2 - Application Circuit with AFC Disabled, and with NTC and CTO Resistor Networks
Charger VIN
14
13
3
11
10
12
2
VCC
CPB
CHRGB
RTIM
CTO
OV_FLT
OVP
Red
Green
R3
IPRGM
NTC
C1
2.2 μF
7
4
1
ITERM
FLTB
GND
BSEN
VOUT
VOUT
AFC
RT
NTC
R11
8
16
15
9
R5
R6
6
R1
R2
5
RGND
C3
C2
2.2μF
SC804A
R4
R12
ERROR
Figure 3a - Application Circuit for Adjust Mode
Charger VIN
14
13
3
11
10
12
2
VCC
CPB
CHRGB
RTIM
CTO
OV_FLT
OVP
Red
Green
R3
IPRGM
NTC
C1
2.2 μF
7
4
1
ITERM
FLTB
GND
BSEN
VOUT
VOUT
AFC
RT
NTC
R11
8
16
15
9
R5
R6
6
R1
R2
R4
R12
5
RGND
C3
C2
2.2μF
SC804A
ERROR
Figure 3b - Application Circuit for Adjust Mode, with Adapter-only Voltage Sensing
© 2005 Semtech Corp.
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SC804A
DRAFT
POWER MANAGEMENT
Applications Information (Cont.)
Overcurrent and Max Temperature Protection
Overcurrentprotectionisinherentinallmodesofoperation.
When the device is in charge mode the output is current-
limited to either the pre-charge current limit value or the
fast charge current limit value depending on the voltage
at the output. Max die temperature protection is also
included. This feature allows the SC804A to operate
with maximum power dissipation by disabling the output
current when the die temperature reaches the maximum
operating temperature. The result is that the SC804A will
operate as a pulse charger in extreme power dissipation
applications, delivering the maximum allowable output
current while regulating the internal die temperature to a
safe level.
0.8
0.6
0.4
0.2
3.2
3.4
3.6
3.8
4
4.2
4.4
4.6
Output voltage, V
Figure 4 - Adjust Mode Minimum Dropout Voltage
The actual dropout voltage is the greater of the Minimum Dropout
Voltage at various programmed VCV and instantaneous VOUT
voltages (shown here, with several programmed VCV voltages
indicated in the figure by ‘o’), and the IR drop due to the product
of IOUT and RDS-ON (not shown here). Adjust mode operation is
ensured for any IOUT current at programmed VCV voltages up to
approximately 4.41V.
Indicator Flags
There are four indicator outputs/LED drivers ont he
SC804A; CPB (Charger Present), CHRGB (Charge Active),
OVPB (Over Voltage Fault), and FLTB (Fault). These outputs
are all active-low; open drain NMOS drivers capable of
sinking up to 10mA. The following table defines each
indicator’s output state.
NOTE: WhenusingAdjustModetoprogramaCVregulation
voltage greater than VCV, care must be taken when CC
charging with a charging adapter operating in current
limit. Adapter current-limited operation occurs when
the adapter current limit is less than the programmed
SC804A fast charge current, such that the adapter voltage
is pulled down to VVOUT plus the SC804A dropout voltage.
A low adapter current limit multiplied by the low minimum
path resistance of the main pass transistor and current
sense resistor (as low as 290mΩ total at extremely low
temperature) can result in a voltage drop from VCC to
VOUT of less than 150mV if the Adjust Mode CV regulation
voltage is programmed above VCV + 50mV. If VVCC - VVOUT
< 150mV, Adjust Mode may not operate correctly. Adjust
Mode will operate correctly whenever the programmed
VOUT CV voltage is less than VCV + 50mV, regardless of the
adapter current limit, because the regulated minimum
dropout voltage is always greater than 150mV in this
case. It will also operate correctly with an adapter current
limit greater than 550 mA, regardless of the programmed
output voltage, because the I-R dropout voltage will
exceed 150mV at even the lowest specified operating
temperature. Normal mode (that is, not Adjust Mode) has
a regulated minimum dropout voltage of approximately
200mV, which is constant for any VVOUT, and so operates
correctly for any adapter current limit.
FLAG
CPB
ON
OFF
UVLO < VCC < OVP
IOUT > ITERM
VCC > OVP
Input out of range
IOUT < ITERM
VCC < OVP
CHRGB
OVPB
VCC > OVP
VCC UVLO
NTC Temp Fault
Pre-Charge Time-out
(OT (Tj > 150°C)
Normal Operation or
NTC Disable
FLTB
The CPB output can be used as a VCC-present indicator.
Regardless of teh state of NTC, the CPB output reflects
the VCC voltage. When VCC is between the UVLO and OVP
thresholds the CPB output is low. If VCC is outside these
limits, this output is high impedance.
The CHRGB output indicates the charging status. When
the output current is greater than ITERM, CHRGB is low.
CHRGB is high impedance when IOUT is less than ITERM.
The CHRGB output is latched during the charge cycle
when the output current is less than ITERM. This latch is
reset when the battery enters a recharge cycle, or if NTC
or VCC are toggled.
© 2005 Semtech Corp.
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SC804A
POWER MANAGEMENT
Charge Mode Timing Diagram
DRAFT
The OVPB signal is an active-low output that signals when
the input voltage exceeds the OVP threshold. When the
voltage on VCC is less than the OVP threshold voltage
this output is high impedance.
and pre-charge timeout. When any of these conditions
occurs the FLTB output goes low; otherwise it remains
high impedance.
The FLTB output is activated when the device experiences
a fault condition. This output can be used to notify the
system controller of a fault condition when connected to
an interrupt input, or it can be used like CPB and CHRGB
to drive an indicator LED. There are five fault modes
signaled by FLTB: input over-voltage, input under-voltage,
NTC temperature out of range, max die temperature (OT),
Capacitor Selection
Low cost, low ESR ceramic capacitors such as the X5R and
X7R dielectric material types are recommended for use with
the SC804A. The output capacitance range is 1ꢀF to 4.7ꢀF.
The input capacitor is typically between 0.1ꢀF to 2.2ꢀF, but
larger values will not degrade performance
UVLO
VCC
VTPreQ
Re-Charge
Threshold
VOUT
Fast Charge
Termination
Current
Soft Start
Pre-Charge
IOUT
CV Mode
CC Mode
CPB
CHRGB
On
Off
On
On
Off
On
On
On
Hold
TIMER
FLTB
Off
Off
On
Off
NTC
Fault
Figure 5 - Charge Mode Timing
© 2005 Semtech Corp.
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SC804A
DRAFT
POWER MANAGEMENT
State Diagram
Over-Voltage, Under-Voltage or
Over-Temperature will force the
SC804A into Shutdown Mode
from any state.
Shutdown Mod:e
VOUT &IOUT off,
OVP > VCC> UVLO
En =Hi
CHRGB High Z,
CPB Low.
Yes
CC = Constant Current
CV = Constant Voltage
Soft Start Vout
CHRGB Low
Timer
Enabled?
Yes
Start Timer
Start Pre- Charge
Yes
Soft Start CC Mode
V
OUT > VTPreQ
OUT =IPREQ
IOUT =IFAST
I
Time>TMAX/4
Yes
V
OUT =VCV
Pre- Charge
Timeout Fault
FLTB goes low.
Cleared by
Yes
Start CV Mode
VBAT> VTPreQ
or Re- cycle VCC
IOUT <ITERM
low temp> NTC Temp> high temp
Yes
CHRGB High Z
NTC out of Range Fault
FLTB goes active low
Timer is frozen
Charge resumes when NTC
Temperature is valid
Timer
Enabled?
Yes
Yes
Monitor Mode
Time>TMAX
VOUT off
Yes
Float Charge Mode
OUT
V
CV
ReQ
<V - V
VOUT =VCV
© 2005 Semtech Corp.
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SC804A
DRAFT
POWER MANAGEMENT
Typical Charge Cycle
Typical Charge Cycle
Evaluation Board configured for internal timer, 1.5V on IPRGM = 843mA, 1.5V on ITERM = 300mA, VCC = 5.0V, Li-Ion
battery capacity = 850mAh. A 237Ω load resistor (18mA at a battery voltage of 4.36V) was applied to the battery fol-
lowing completion of precharge, to slowly discharge the battery following charge timer timeout to illustrate a recharge
cycle. The alphabetic markers indicate the following: (a) precharge; (b) fast charge, or Constant Current (CC) charg-
ing; (c) Constant Voltage (CV) charging; (d) termination; (e) CV (“float”) charging until charge timer timeout; (f) charge
timer timeout; (g) discharge of the battery due to 18mA load; (h) recharge cycle initiated when battery voltage drops
below the recharge threshold.
5
g
c
e
f
4.36
4
b
3.5
3
a
2.5
2
h
d
1.5
1
0.5
0
0
30
60
90
120
150
180
210
240
270
300
330
360
Time (minutes)
900
800
700
600
500
400
300
200
100
0
b
c
a
h
f
0
30
60
90
120
150
180
210
240
270
300
330
360
Time (minutes)
© 2005 Semtech Corp.
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SC804A
DRAFT
POWER MANAGEMENT
Typical Characteristics
VOUT VCV Line Regulation vs. Load, T = +25°C
VOUT VCV Load Regulation vs. Line, T = +25°C
4.356
4.356
4.354
4.352
4.350
4.348
4.346
4.344
4.342
4.340
4.338
VCC = 5.0V
Iout = 500mA
4.354
VCC = 5.5V
4.352
4.350
Iout = 750mA
4.348
VCC = 6.0V
Iout = 1000mA
4.346
4.344
VCC = 6.5V
4.342
Iout = 1500mA
4.340
4.338
5.00
5.20
5.40
5.60
5.80
6.00
6.20
6.40
500
750
1000
1250
1500
VIN (V)
IOUT (mA)
VOUT VCV Regulation vs. Temperature,
VCC = 5.0V, IOUT = 800mA
IOUT Line Regulation vs. Temperature,
RPRGM = 1.87kΩ
4.360
4.358
4.356
4.354
4.352
4.350
4.348
840
836
832
828
824
820
816
T = +85°C
T = +25°C
T = -40°C
5.00
5.25
5.50
5.75
6.00
6.25
6.50
-50
-25
0
25
50
75
100
Ambient Temperature, °C
VCC, V
Precharge and Termination Current vs.
ITERM Resistance
IOUT vs. IPRGM Resistance, T = +25°C
1800
1600
1400
1200
1000
800
400.0
350.0
300.0
250.0
200.0
150.0
100.0
50.0
600
400
0.0
0.3
0.5
0.7
0.9
1.1
0
0.5
1
1.5
2
2.5
1/Riprgm, 1/k
Ω
1/RIPRGM, 1/k
Ω
© 2005 Semtech Corp.
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SC804A
DRAFT
POWER MANAGEMENT
Typical Characteristics (Cont.)
Dropout Voltage vs. IOUT
Rds-on vs. IOUT
0.900
0.620
0.570
0.520
0.470
0.420
0.370
0.320
0.270
TJ = +125°C
0.800
TJ = +125°C
0.700
TJ = +85°C
0.600
TJ = +85°C
0.500
0.400
0.300
TJ = +25°C
TJ = -40°C
TJ = +25°C
0.200
TJ = - 40°C
0.100
400
600
800
1000
1200
1400
1600
400
600
800
1000
1200
1400
1600
IOUT (mA)
IOUT (mA)
AFC Operation, RPRGM = 1.87kΩ
1200
1000
800
600
400
200
0
AFC Pin Tied to VCC
Actual AFC Response
Ideal AFC Response
0
0.5
1
1.5
2
VAFC, V
© 2005 Semtech Corp.
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SC804A
DRAFT
POWER MANAGEMENT
Evaluation Board Schematic
CHARGER+
CHARGER-
RTIM
C1
1
2
2.2u
R9
R10
1
2
2
1
<NM>
<NM>
JP6
JP1
D1
1
1
2
R1
VOUT
2
1
2
2
1
D2
D3
D4
390
R15
1
2
1
R11
0
C2
2.2u
C3
<NM>
1
2
GND
CTO
1
1
37.4k
1
2
3
4
12
BSEN
CTO
RTIM
CPB
3
2
1
R2
JP2
JP3
JP5
11
10
9
1
1
2
2
1
1
2
U1
SC804A
390
R3
1
2
IPRGM
ITERM
CHRGB
AFC
390
R13
JP7
IPRGM
ITERM
2
1
2
1
1
100k
R12
<NM>
R6
1.87k
R5
499
R4
JP4
1
2
1
2
R14
390
2
1
1
2
1
1
RGND
0
R8
R7
1
2
GND
GND
1
1
<NM>
R16
10k
3
1
NTC
POT_3296W-105
Evaluation Board Gerber Plot,Top/Bottom Views
© 2005 Semtech Corp.
19
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SC804A
DRAFT
POWER MANAGEMENT
Outline Drawing - MLPQ-16
DIMENSIONS
INCHES MILLIMETERS
DIM
A
MIN NOM MAX MIN NOM MAX
A
D
-
-
-
-
.031
A1 .000
.040 0.80
.002 0.00
1.00
0.05
-
B
E
-
(.008)
-
-
(0.20)
A2
b
D
.010 .012 .014 0.25 0.30 0.35
.153 .157 .161 3.90 4.00 4.10
PIN 1
INDICATOR
(LASER MARK)
D1 .079 .085 .089 2.00 2.15 2.25
.153 .157 .161 3.90 4.00 4.10
E1 .079 .085 .089 2.00 2.15 2.25
E
e
.026 BSC
0.65 BSC
L
N
.012 .016 .020 0.30 0.40 0.50
16
16
aaa
bbb
.003
.004
0.08
0.10
A2
A
SEATING
PLANE
aaa
C
A1
C
D1
e/2
LxN
E/2
E1
2
1
N
e
bxN
bbb
C
A B
D/2
NOTES:
1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS.
Marking Information
804A
yyww
xxxxx
xxxx
yyww = Date Code (Example: 0552)
xxxxx xxxx = Semtech Lot Number
(Example: E9010 01-1)
© 2005 Semtech Corp.
20
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SC804A
DRAFT
POWER MANAGEMENT
Land Pattern - MLPQ-16
K
DIMENSIONS
DIM
INCHES
MILLIMETERS
(.156)
.122
.091
.091
.026
.016
.033
.189
(3.95)
3.10
2.30
2.30
0.65
0.40
0.85
4.80
C
G
H
K
P
X
Y
Z
2x Z
H
2x G
Y
2x (C)
X
P
NOTES:
1. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
Contact Information
Semtech Corporation
Power Management Products Division
200 Flynn Road, Camarillo, CA 93012
Phone: (805) 498-2111 FAX (805)498-3804
© 2005 Semtech Corp.
21
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