MIC79050
Simple Lithium-Ion Battery Charger
Features
General Description
• High-Accuracy Charge Voltage: ±0.75% over
–5°C to + 60°C (Li-ion charging temperature
range)
• Zero Off-Mode Current
• 10 µA Reverse Leakage
• Ultra-Low 380 mV Dropout at 500 mA
• Wide Input Voltage Range
• Logic-Controlled Enable Input (8-Lead Devices
Only)
• Thermal Shutdown and Current-Limit Protection
• Power MSOP-8, Power SOIC-8, and SOT-223
Packages
• Pulse Charging Capability
The MIC79050 is a simple single-cell lithium-ion battery
charger. It includes an on-chip pass transistor for high
precision charging. Featuring ultra-high precision
(±0.75% over the Li-ion battery charging temperature
range) and “zero” off-mode current, the MIC79050
provides a very simple, cost effective solution for
charging lithium-ion battery.
Applications
•
•
•
•
•
Li-Ion Battery Charger
Cellular Phones
Palmtop Computers
PDAs
Self-Charging Battery Packs
Other features of the MIC79050 include current-limit
and thermal shutdown protection. In the event the input
voltage to the charger is disconnected, the MIC79050
also
provides
minimal
reverse-current
and
reversed-battery protection.
The MIC79050 is a fixed 4.2V device and comes in the
thermally-enhanced MSOP-8, SOIC-8, and SOT-223
packages. The 8-lead versions also come equipped
with enable and feedback inputs. All versions are
specified over the temperature range of –40°C to
+125°C.
Package Types
MIC79050
3-Lead SOT-223 (S)
GND
TAB
1
IN
2
MIC79050
8-Lead SOIC/MSOP (M/MM)
EN 1
8
GND
IN 2
7
GND
BAT 3
6
GND
FB 4
5
GND
3
GND BAT
2017 - 2022 Microchip Technology Inc. and its subsidiaries.
DS20005771B-page 1
MIC79050
Typical Application Circuits
Pulse-Charging
Application
Simplest Battery Charging
Solution
Regulated or
unregulated
wall adapter
MIC79050-4.2YS
IN
BAT
4.2V 0.75% over Temp
Li-Ion
Cell
GND
MIC79050-4.2YMM
Regulated or
unregulated
wall adapter
IN
BAT
EN
FB
GND
4.2V 0.75%
Li-Ion
Cell
External PWM*
*See Applications Information
Functional Block Diagrams
3-Lead Version
VIN
VBAT
IN
Bandgap
Ref.
Current Limit
Thermal Shutdown
MIC79050-4.2YS
GND
8-Lead Version
VIN
VBAT
IN
FB
Bandgap
VRef.
REF
EN
Current Limit
Thermal Shutdown
MIC79050-4.2YM/YMM
GND
DS20005771B-page 2
2017 - 2022 Microchip Technology Inc. and its subsidiaries.
MIC79050
1.0
ELECTRICAL CHARACTERISTICS
Absolute Maximum Ratings †
Supply Input Voltage (VIN) .......................................................................................................................... –20V to +20V
Power Dissipation (PD) (Note 1) ............................................................................................................ Internally Limited
Operating Ratings ‡
Supply Input Voltage (VIN) ......................................................................................................................... +2.5V to +16V
Enable Input Voltage (VEN) .................................................................................................................................0V to VIN
† Notice: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.
This is a stress rating only and functional operation of the device at those or any other conditions above those indicated
in the operational sections of this specification is not intended. Exposure to maximum rating conditions for extended
periods may affect device reliability.
‡ Notice: The device is not guaranteed to function outside its operating ratings.
Note 1: The maximum allowable power dissipation at any TA (ambient temperature) is calculated using: PD(max) =
(TJ(max) – TA) ÷ θJA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown.
ELECTRICAL CHARACTERISTICS
Electrical Characteristics: VIN = VBAT + 1.0V; COUT = 4.7 μF, IOUT = 100 μA; TJ = +25°C, bold values indicate
–40°C ≤ TJ ≤ +125°C; unless noted.
Parameter
Symbol
Min.
Typ.
Max.
Units
VBAT
–0.75
—
0.75
%
Battery Voltage Temperature
Coefficient
ΔVBAT/
ΔT
—
40
—
ppm/°C
Line Regulation
ΔVBAT/
VBAT
—
0.009
0.05
—
—
0.1
Load Regulation
ΔVBAT/
VBAT
—
0.05
0.5
—
—
0.7
VIN –
VBAT
—
380
500
—
—
600
—
85
130
—
—
170
—
11
20
—
—
25
—
0.05
3
Battery Voltage Accuracy
Dropout Voltage (Note 3)
Ground Pin Current (Note 4,
Note 5)
Ground Pin Quiescent
Current (Note 5)
IGND
IGND
Ripple Rejection
PSRR
Current Limit
ILIMIT
Thermal Regulation
ENABLE Input
Enable Input Logic-Low
Voltage
ΔVBAT/
ΔPD
VENL
—
0.10
8
—
75
—
—
750
900
—
—
1000
—
0.05
—
—
0.4
—
—
—
0.18
2.0
—
—
2017 - 2022 Microchip Technology Inc. and its subsidiaries.
%/V
%
Conditions
Variation from nominal VOUT, –5°C
to +60°C
Note 1
VIN = VBAT + 1V to 16V
IOUT = 100 μA to 500 mA, Note 2
mV
IOUT = 500 mA
µA
VEN ≥ 3.0V, IOUT = 100 μA
mA
VEN ≥ 3.0V, IOUT = 500 mA
µA
VEN ≤ 0.4V (shutdown)
VEN ≤ 0.18V (shutdown)
dB
f = 120 Hz
mA
VBAT = 0V
%/W
V
Note 6
VEN = logic-low (shutdown)
VEN = logic-high (enabled)
DS20005771B-page 3
MIC79050
ELECTRICAL CHARACTERISTICS (CONTINUED)
Electrical Characteristics: VIN = VBAT + 1.0V; COUT = 4.7 μF, IOUT = 100 μA; TJ = +25°C, bold values indicate
–40°C ≤ TJ ≤ +125°C; unless noted.
Parameter
Symbol
Enable Input Current
IENL
—
IENH
Note 1:
2:
3:
4:
5:
6:
Min.
Typ.
Max.
—
0.01
–1
—
0.01
–2
—
5
20
—
—
25
Units
µA
µA
Conditions
VENL ≤ 0.4V (shutdown)
VENL ≤ 0.18V (shutdown)
VENH ≥ 2.0V (enabled)
Battery voltage temperature coefficient is the worst case voltage change divided by the total temperature
range.
Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are
tested for load regulation in the load range from 100 μA to 500 mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Dropout voltage is defined as the input to battery output differential at which the battery voltage drops 2%
below its nominal value measured at 1V differential.
Ground pin current is the charger quiescent current plus pass transistor base current. The total current
drawn from the supply is the sum of the load current plus the ground pin current.
VEN is the voltage externally applied to devices with the EN (enable) input pin. MSOP-8 (MM) and SOIC-8
(M) packages only.
Thermal regulation is the change in battery voltage at a time “t” after a change in power dissipation is
applied, excluding load or line regulation effects. Specifications are for a 500 mA load pulse at VIN = 16V
for t = 10 ms.
DS20005771B-page 4
2017 - 2022 Microchip Technology Inc. and its subsidiaries.
MIC79050
TEMPERATURE SPECIFICATIONS (Note 1)
Parameters
Sym.
Min.
Typ.
Max.
Units
Conditions
Junction Operating Temperature
Range
TJ
–40
—
+125
°C
—
Storage Temperature Range
TS
–65
—
+150
°C
—
Lead Temperature
—
—
—
+260
°C
Soldering, 5s
Thermal Resistance MSOP-8
JA
—
80
—
°C/W
—
Thermal Resistance SOIC-8
JA
—
63
—
°C/W
—
JC
—
15
—
°C/W
—
JA
—
62
—
°C/W
—
Temperature Ranges
Package Thermal Resistances (Note 2)
Thermal Resistance SOT-223
Note 1:
2:
The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable
junction temperature and the thermal resistance from junction to air (i.e., TA, TJ, JA). Exceeding the
maximum allowable power dissipation will cause the device operating junction temperature to exceed the
maximum +125°C rating. Sustained junction temperatures above +125°C can impact the device reliability.
The maximum allowable power dissipation at any TA (ambient temperature) is calculated using: PD(max) =
(TJ(max) – TA) ÷ θJA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown.
2017 - 2022 Microchip Technology Inc. and its subsidiaries.
DS20005771B-page 5
MIC79050
2.0
Note:
TYPICAL PERFORMANCE CURVES
The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.
5
OUTPUT VOLTAGE (V)
DROPOUT VOLTAGE (mV)
400
300
200
100
0
0
Dropout Voltage vs. Output
GROUND CURRENT (mA)
DROPOUT VOLTAGE (mV)
400
300
200
100
0
-40
0
40
80
TEMPERATURE (°C)
FIGURE 2-2:
Temperature.
2
4
INPUT VOLTAGE (V)
6
Dropout Characteristics.
10
8
6
4
2
0
0
120
Dropout Voltage vs.
FIGURE 2-5:
Current.
100 200 300 400 500
OUTPUT CURRENT (mA)
Output Current vs. Ground
1.5
4
3
2
5mA
50mA, 150mA
2 4 6 8 10 12 14 16
INPUT VOLTAGE (V)
FIGURE 2-3:
DS20005771B-page 6
Dropout Characteristics.
GROUND CURRENT (mA)
5
OUTPUT VOLTAGE (V)
1
12
500
0
0
500mA
2
FIGURE 2-4:
600
1
250mA
3
0
0
100 200 300 400 500
OUTPUT CURRENT (mA)
FIGURE 2-1:
Current.
4
50mA
1
5mA
0.5
0
0
FIGURE 2-6:
Voltage.
4
8
12
SUPPLY VOLTAGE (V)
16
Ground Current vs. Supply
2017 - 2022 Microchip Technology Inc. and its subsidiaries.
MIC79050
20
13.5
GROUND CURRENT (mA)
GROUND CURRENT (mA)
25
500mA
15
10
5
0
0
FIGURE 2-7:
Voltage.
250mA
125mA
1
2
3
4
5
SUPPLY VOLTAGE (V)
OUTPUT VOLTAGE (V)
0
40
80
TEMPERATURE (°C)
120
Ground Current vs.
GROUND CURRENT (mA)
4.0
3.8
3.6
3.4
3.2
FIGURE 2-9:
Temperature.
0
40
80
TEMPERATURE (°C)
120
Ground Current vs.
4.205
4.200
4.195
4.190
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
FIGURE 2-11:
Temperature.
SHORT CIRCUIT CURRENT (mA)
GROUND CURRENT (μA)
50
3.0
-40
11.5
4.210
100
FIGURE 2-8:
Temperature.
12.0
FIGURE 2-10:
Temperature.
150
0
-40
12.5
11.0
-40
6
Ground Current vs. Supply
13.0
0
40
80
TEMPERATURE (°C)
120
Ground Current vs.
2017 - 2022 Microchip Technology Inc. and its subsidiaries.
Battery Voltage vs.
800
700
600
500
400
300
200
100
0
-40
FIGURE 2-12:
Temperature.
0
40
80
TEMPERATURE (°C)
120
Short-Circuit Current vs.
DS20005771B-page 7
0.25
Upper
Lower
-0.25
-0.75
0
200
REVERSE LEAKAGE CURRENT (μA)
FIGURE 2-13:
vs. Time.
400
600
TIME (hrs)
800
Typical Voltage Drift Limits
20
15
10
5
0
0
1
2
3
4
OUTPUT VOLTAGE (V)
5
FIGURE 2-14:
Reverse Leakage Current
vs. Output Voltage.
DS20005771B-page 8
REVERSE LEAKAGE CURRENT (μA)
0.75
20
4.2V
15
3.6V
10 3.0V
5
VIN+VE N
FLOATING
5
15 25 35 45 55
TEMPERATURE (°C)
0
-5
FIGURE 2-15:
Reverse Leakage Current
vs. Output Voltage.
REVERSE LEAKAGE CURRENT (μA)
DRIFT FROM NOMINAL VOUT (%)
MIC79050
20
4.2V
15
3.6V
10 3.0V
5
V +V
IN
0
-5
FIGURE 2-16:
vs. Temperature.
EN
GROUNDED
5
15 25 35 45 55
TEMPERATURE (°C)
Reverse Leakage Current
2017 - 2022 Microchip Technology Inc. and its subsidiaries.
MIC79050
3.0
PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
Pin Number
SOT-223
PIN FUNCTION TABLE
Pin Number
SOIC-8,
MSOP-8
Pin Name
1
2
IN
2, TAB
5, 6, 7, 8
GND
Description
Supply input.
Ground: SOT-223 pin 2 and TAB are internally connected. SOIC-8
pins 5 through 8 are internally connected.
3
3
BAT
Battery voltage output.
—
1
EN
Enable (Input): TTL/CMOS-compatible control input. Logic-high =
enable; logic-low or open = shutdown.
—
4
FB
Feedback node.
2017 - 2022 Microchip Technology Inc. and its subsidiaries.
DS20005771B-page 9
MIC79050
4.0
FUNCTIONAL DESCRIPTION
The MIC79050 is a high-accuracy, linear battery
charging circuit designed for the simplest
implementation of a single lithium-ion (Li-ion) battery
charger. The part can operate from a regulated or
unregulated power source, making it ideal for various
applications. The MIC79050 can take an unregulated
voltage source and provide an extremely accurate
termination voltage. The output voltage varies only
0.75% from nominal over the standard temperature
range for Li-ion battery charging (–5°C to +60°C). With
a minimum of external components, an accurate
constant-current charger can be designed to provide
constant-current, constant-voltage charging for Li-ion
cells.
4.1
Input Voltage
The MIC79050 can operate with an input voltage up to
16V (20V absolute maximum), ideal for applications
where the input voltage can float high, such as an
unregulated wall adapter that obeys a load-line. Higher
voltages can be sustained without any performance
degradation to the output voltage. The line regulation of
the device is typically 0.009%/V; that is, a 10V change
on the input voltage corresponds to a 0.09% change in
output voltage.
4.2
4.3
Feedback
The feedback pin allows for external manipulation of
the control loop. This node is connected to an external
resistive divider network, which is connected to the
internal error amplifier. This amplifier compares the
voltage at the feedback pin to an internal voltage
reference. The loop then corrects for changes in load
current or input voltage by monitoring the output
voltage and linearly controlling the drive to the large,
PNP pass element. By externally controlling the
voltage at the feedback pin the output can be disabled
or forced to the input voltage. Pulling and holding the
feedback pin low forces the output low. Holding the
feedback pin high forces the pass element into
saturation, where the output will be the input minus the
saturation (dropout) voltage.
4.4
Battery Output
The BAT pin is the output of the MIC79050 and
connects directly to the cell to provide charging current
and voltage. When the input is left floating or grounded,
the BAT pin limits reverse current to
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