Data Sheet

Freescale Semiconductor
Advance Information
Document Number: MC34675
Rev. 3.0, 4/2008
28V-Input-Voltage Single-Cell
Li-Ion Battery Charger with
10mA Regulator
34675
The 34675 is a high-input-voltage Li-Ion battery charger with a
4.85V/10mA linear regulator. The high input voltage, up to 28V,
eliminates the input over-voltage protection circuit required in handheld
devices such as cell phones, Bluetooth accessories, and portable
media players. The 4.85V linear regulator is capable of 10mA output
current and can be used to directly power a sub-system such as a USB
transceiver.
The charge cycle of the 34675 includes trickle, constant-current
(CC) and constant-voltage (CV) charge modes. The CC mode current
is programmable up to 1A, with an external resistor. The voltage across
the external resistor is also used to monitor the actual charge current.
The constant voltage is fixed at 4.2V with 0.7% accuracy over the
-40°C to 85°C temperature range. The trickle-mode current is pre-set
to 20% of the CC mode current when the battery voltage is lower than
the trickle-mode threshold. The end-of-charge (EOC) current threshold
is pre-set to 10% of the CC mode current, to save board space and
cost. A charge current thermal foldback feature limits the charge
current when the IC internal temperature rises to the preset threshold
of 120°C. The 34675 also protects the system with its input overvoltage protection (OVP) feature. Two indication pins (PPR and CHG)
can be simply interfaced to a microprocessor or LEDs. When no power
supply is connected, or when disabled, the charger draws less than
1.0μA leakage current from the battery.
POWER MANAGEMENT IC
EP SUFFIX (PB-FREE)
98ASA10774D
8-PIN UDFN
ORDERING INFORMATION
Device
Temperature
Range (TA)
Package
MC34675AEP/R2
-40°C to 85°C
8-UDFN
Features
•
•
•
•
•
•
•
•
•
•
No external MOSFET, reverse-blocking diode, or current-sense resistor is required
Guaranteed maximum 1A programmable CC mode current
±0.7% voltage accuracy over -40°C to 85°C
±6% current accuracy over -40°C to 85°C
4.85V/10mA linear regulator with a 6.8V input over-voltage protection threshold
28V maximum voltage for the power input with a 6.8V over-voltage protection threshold
Trickle charge for fully discharged batteries
Charge current monitor
Charge current thermal foldback
Pb-free packaging designated by suffix code EP
34675
VIN
CIN
VIN
GND
TO BATTERY
BAT
COUT
ISET
RISET
CHG
PPR
OFF
EN
TO SYSTEM
DET
CDET
ON
Figure 1. 34675 Simplified Application Diagram
* This document contains certain information on a new product.
Specifications and information herein are subject to change without notice.
© Freescale Semiconductor, Inc., 2008. All rights reserved.
INTERNAL BLOCK DIAGRAM
INTERNAL BLOCK DIAGRAM
VIN
BAT
VIN
Monitor
–
+
Internal
Supply
Linear
Reg
VREF
Charge
Control
DET
+
VOS
PPR
ISET
–
REF
VIN + –
BAT
IREF
+
–
–
+
Die
Temp
120°C
CHG
EN
Logic
Control
+
–
IEOC
GND
Figure 2. 34675 Simplified Internal Block Diagram
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Analog Integrated Circuit Device Data
Freescale Semiconductor
PIN CONNECTIONS
PIN CONNECTIONS
Transparent
Top View
VIN
1
8
BAT
PPR
2
7
ISET
CHG
3
6
DET
EN
4
5
GND
EPAD
Figure 3. 34675 Pin Connections
Table 1. 34675 Pin Definitions
A functional description of each pin can be found in the Functional Pin Description section beginning on page 12.
Pin Number
Pin Name
Pin Function
Formal Name
Definition
1
VIN
Input
Input supply
2
PPR
Output
Power present
indicator
3
CHG
Output
Charge indicator
4
EN
Input
Enable
Enable logic input.
5
GND
Ground
Ground
Ground.
6
DET
Output
Regulator output
7
ISET
Output
CC mode current
setting and charge
current monitor
8
BAT
Output
Charger output
EPAD
EPAD
N/A
Exposed pad
The power supply input.
Indication of the input power status. Open drain output.
Indication of the charge status. Open drain output.
The 4.85V/10mA linear regulator output.
CC mode current setting and charge current monitoring pin.
The charger output pin. Connect this pin to the Li-Ion battery.
The exposed pad for thermal dissipation enhancement. It must be
soldered on the large ground plane on the PCB to increase the thermal
dissipation. The pad must be connected to GND electrically
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Analog Integrated Circuit Device Data
Freescale Semiconductor
3
ELECTRICAL CHARACTERISTICS
MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
MAXIMUM RATINGS
Table 2. Maximum Ratings
All voltages are with respect to ground unless otherwise noted. Exceeding these ratings may cause a malfunction or
permanent damage to the device.
Ratings
Symbol
Value
Unit
ELECTRICAL RATINGS
Input Voltage Range
V
VIN Pin
VIN
-0.3 to 28
PPR and CHG Pins
VPPR, VCHG
-0.3 to 12
EN, BAT, ISET and DET Pins
VEN, VBAT,
VISET, VDET
-0.3 to 5.5
ESD Voltage(1)
V
Human Body Model (HBM)
VESD
Machine Model (MM)
±2000
±200
THERMAL RATINGS
Operating Temperature
°C
Ambient
TA
-40 to +85
Junction
TJ
-40 to 150
TSTG
-65 to +150
RθJC
10
RθJA
70
TPPRT
Note 4
Storage Temperature
Thermal
Resistance(2)
°C/W
Junction-to-Case
Junction-to-Ambient
Peak Package Reflow Temperature During
°C
Reflow(3),(4)
°C
Notes
1. ESD testing is performed in accordance with the Human Body Model (HBM) (CZAP = 100pF, RZAP = 1500Ω), and the Machine Model
(MM) (CZAP = 200pF, RZAP = 0Ω).
2.
3.
4.
Device mounted on the Freescale EVB test board per JEDEC DESD51-2.
Pin soldering temperature limit is for 10 seconds maximum duration. Not designed for immersion soldering. Exceeding these limits may
cause malfunction or permanent damage to the device.
Freescale’s Package Reflow capability meets Pb-free requirements for JEDEC standard J-STD-020C. For Peak Package Reflow
Temperature and Moisture Sensitivity Levels (MSL), Go to www.freescale.com, search by part number [e.g. remove prefixes/suffixes
and enter the core ID to view all orderable parts. (i.e. MC33xxxD enter 33xxx), and review parametrics.
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Analog Integrated Circuit Device Data
Freescale Semiconductor
ELECTRICAL CHARACTERISTICS
STATIC ELECTRICAL CHARACTERISTICS
STATIC ELECTRICAL CHARACTERISTICS
Table 3. Static Electrical Characteristics
Characteristics noted under conditions VIN = 5V, -40°C ≤ TA ≤ 85°C, CIN = 1.0μF, COUT = 2.2μF, CDET = 0.22μF (see Figure 1),
unless otherwise noted. Typical values noted reflect the approximate parameter means at VIN = 5V and TA = 25°C under nominal
conditions, unless otherwise noted.
Characteristic
Symbol
Min
Typ
Max
Unit
VIN Pin Normal Operation Input Voltage Range(5)
VIN
2.6
-
6.6
V
VIN Pin Supply Current
IIN
Charger enabled(6)
-
1400
2000
Charger disabled
-
360
450
POWER INPUT
Regulated Output Voltage
μA
VBAT
V
VIN = 5.0V; IBAT = 10mA; TA = 25°C
4.185
4.20
4.215
VIN = 5.0V; IBAT = 10mA; TA = -40 to 85°C
4.170
4.20
4.230
Power MOSFET On Resistance
RDS(ON)
mΩ
VBAT = 4.0V; IBAT = 400mA; ICHG = 500mA
BAT Pin Standby Current
330
475
-
-
1.0
μA
ISTDBY
VIN not powered or charger disabled
Power On Reset
-
VPOR
V
Rising VIN threshold
3.5
3.6
3.7
Falling VIN threshold
2.4
2.5
2.6
VIN-BAT Offset Voltage
VOS
mV
Rising threshold
-
-
60
Falling threshold
1.0
-
22
VOVP
6.6
6.8
7.0
V
VOVPHYS
-
200
-
mV
Constant Current Mode Charge Current Range(7)
ICHG
0.05
-
1.0
A
ICHG Accuracy
ICHG
For ICHG between 300mA to 1000mA (tested at 450mA)
94%
100%
106%
For ICHG between 50mA to 300mA(7)
90%
100%
110%
18%
20%
22%
When ICHG >300mA (tested at ICHG=450mA)
8.5%
10%
11.5%
When ICHG <300mA(7)
8.0%
10%
12%
-
1.0
-
Over-voltage Protection Rising Threshold
Over-voltage Protection Threshold Hysteresis
CHARGE CURRENT
Trickle-Mode Charge Current
ITRKL
End-of-Charge (EOC) Threshold
IEOC
ISET-Pin Voltage for ICHG Reference
ICHG
ICHG
ICHG
VISET
V
Notes
5. Refer to the Power-on-Reset parameter for VIN turn on and turn off values.
6.
7.
Supply current does not include the current delivered to the battery through the BAT pin.
Not tested. The accuracy is guaranteed by design.
34675
Analog Integrated Circuit Device Data
Freescale Semiconductor
5
ELECTRICAL CHARACTERISTICS
STATIC ELECTRICAL CHARACTERISTICS
Table 3. Static Electrical Characteristics (continued)
Characteristics noted under conditions VIN = 5V, -40°C ≤ TA ≤ 85°C, CIN = 1.0μF, COUT = 2.2μF, CDET = 0.22μF (see Figure 1),
unless otherwise noted. Typical values noted reflect the approximate parameter means at VIN = 5V and TA = 25°C under nominal
conditions, unless otherwise noted.
Characteristic
Symbol
Min
Typ
Max
Unit
VTRKL
2.6
2.7
2.8
V
VTRKLHYS
40
100
150
mV
VRECH
4.075
4.100
4.125
V
VRECHHYS
-
25
50
mV
4.6
4.85
5.0
-
90
150
10
13
16
CHARGE THRESHOLDS
Trickle Mode Rising Threshold Voltage
Trickle Mode Threshold Voltage Hysteresis
Recharge Threshold Voltage
Recharge Falling Threshold Voltage Hysteresis
LINEAR REGULATOR
Output Voltage
VLR
VIN = 5.2V, Output Current < 10mA, IBAT = 0mA
Dropout Voltage
V
VDO
VIN = 4.7V, Output Current = 10mA, IBAT = 0mA
Output Current Limit
IREGLMT
Output Pull-down Resistance
RREGPD
2.0V < VIN < VPOR or VIN > VOVP
mV
mA
kΩ
-
200
-
LOGIC INPUT AND OUTPUT
EN Input High Threshold Voltage
VIH
1.5
-
-
V
EN Input Low Threshold Voltage
VIL
-
-
0.5
V
EN Input Pull-down Current
IEN
-
2.0
7.5
9.0
15
-
VEN = 3V
PPR and CHG Sink Current when the Output is Low
IPCSINKL
VCHG = VPPR = 0.6V
PPR and CHG Leakage Current When the Output is High-impedance
μA
mA
μA
IPCLEAKH
VCHG = VPPR = 5.0V
-
-
1.0
100
120
140
CHARGE CURRENT THERMAL FOLDBACK
Current Foldback Die Temperature Limit
TLIMIT
°C
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Analog Integrated Circuit Device Data
Freescale Semiconductor
ELECTRICAL CHARACTERISTICS
DYNAMIC ELECTRICAL CHARACTERISTICS
DYNAMIC ELECTRICAL CHARACTERISTICS
Table 4. Dynamic Electrical Characteristics
Characteristics noted under conditions VIN = 5V, -40°C ≤ TA ≤ 85°C, CIN = 1μF, COUT = 2.2μF, CDET = 0.22μF (see Figure 1),
unless otherwise noted. Typical values noted reflect the approximate parameter means at VIN = 5V and TA = 25°C under nominal
conditions, unless otherwise noted.
Characteristic
Symbol
Min
Typ
Max
Unit
tEOC
6.0
8.0
12
ms
fOSC
40.0
50.0
60.0
kHz
END OF CHARGE
EOC Filter Time
OSCILLATOR
Oscillation Frequency
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Analog Integrated Circuit Device Data
Freescale Semiconductor
7
ELECTRICAL CHARACTERISTICS
ELECTRICAL PERFORMANCE CURVES
30
60
16
BAT Pin Output Voltage (V)
Figure 4. Complete Charge Cycle
VIN = 5.0V, ICHG=400mA, 740mAh Li-Ion Battery, TA=25°C
4.3
4.2
4.1
4.0
3.9
3.8
3.7
3.6
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
12
IBAT (µA)
450
400
Battery Voltage
350
300
250
200
Charge Current
150
100
50
0
90 120 150 180 210 240
Time (min)
8
4
0
-4
0
1
Trickle Charge Current (mA)
VIN Pin Supply Current (µA)
1500
Charger Enabled
1200
900
600
Charger Disabled
300
0
3
4
5
6
Input Voltage (V)
7
Figure 6. VIN Pin Supply Current vs VIN
IBAT = 0mA, TA = 25°C
5
RISET=3.95 kΩ
1000
800
RISET=7.9 kΩ
600
400
RISET=15.8 kΩ
200
0
3.5
4.0
4.5 5.0 5.5 6.0
Input Voltage (V)
6.5
7.0
Figure 8. Constant Charge Current vs VIN
VBAT = 3.7V, TA = 25°C
Figure 5. Charger Output Voltage vs VIN
IBAT = 0mA, TA = 25°C
1800
4
1200
Input Voltage (V)
2100
2
3
VBAT (V)
Figure 7. BAT Pin Current vs Battery Voltage in OVP
VIN = 7.0V, TA = 25°C
Constant Charge Current (mA)
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0
Charge Current (mA)
Battery Voltage (V)
ELECTRICAL PERFORMANCE CURVES
250
RISET=3.95 kΩ
200
150
RISET=7.9 kΩ
100
RISET=15.8 kΩ
50
0
3
4
5
6
Input Voltage (V)
7
Figure 9. Trickle Charge Current vs VIN
VBAT = 2.0V, TA = 25°C
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Analog Integrated Circuit Device Data
Freescale Semiconductor
ELECTRICAL CHARACTERISTICS
ELECTRICAL PERFORMANCE CURVES
DET Pin Output Voltage (V)
Charge Current (mA)
1200
RISET=3.95 kΩ
1000
800
600
RISET=7.9 kΩ
400
RISET=15.8 kΩ
200
0
0
1
2
3
4
5
5
4
VIN Rising
3
2
VIN Falling
1
0
0
1
Battery Voltage (V)
1.2
5.00
1.0
4.95
0.8
4.90
0.6
0.4
7
4.85
4.80
0.2
4.75
0.0
4.0
4.5
5.0
5.5
6.0
VIN (V)
6.5
4.70
0
7.0
Figure 11. VISET vs VIN
VBAT = 3.7V, TA = 25°C
200
400
600
IBAT (mA)
800
1000
Figure 14. DET Pin Output Voltage vs Charge Current
VIN = 5.2V, IDET = 10mA, TA = 25°C
5.00
1.2
RISET=15.8kΩ RISET=7.9kΩ
1.0
RISET=3.95 kΩ
0.8
4.95
VDET (V)
VISET (V)
6
Figure 13. DET Pin Output Voltage vs Input Voltage
RDET = 470Ω, IBAT = 0mA, TA = 25°C
VDET (V)
VISET (V)
Figure 10. Charge Current vs Battery Voltage
VIN = 5.0V, TA = 25°C
2
3
4
5
Input Voltage (V)
0.6
4.90
4.85
0.4
4.80
0.2
4.75
0.0
0
200
400 600 800 1000 1200
Charge Current (mA)
Figure 12. VISET vs Charge Current
VIN = 5.0V, TA = 25°C
4.70
0
2
4
6
8
IDET (mA)
10
12
14
Figure 15. DET Pin Output Voltage vs Output Current
VIN = 5.2V, IBAT = 0mA, TA = 25°C
34675
Analog Integrated Circuit Device Data
Freescale Semiconductor
9
160
85°C
25°C
120
-40°C
80
40
0
0
2
4
6
8
10
DET Pin Output Current (mA)
12
Figure 16. DET Dropout Voltage vs Output Current
VIN = 4.7V, IBAT = 0mA
250
150
RISET=7.9kΩ
100
RISET=15.8kΩ
50
0
-40
-20
0
20
40
60
Temperature (°C)
80
1.10
4.210
4.205
1.05
4.200
4.195
1.00
4.190
0.95
4.185
4.180
-40
-20
0
20
40
60
Temperature (°C)
0.90
-40
80
Figure 17. Charger Output Voltage vs Temperature
VIN = 5.0V, IBAT = 0mA
1200
0
20
40
60
Temperature (°C)
80
450
RISET=3.95kΩ
1000
400
800
RISET=7.9kΩ
600
400
RISET=15.8kΩ
350
300
250
200
0
-40
-20
Figure 20. VISET vs Temperature
VIN = 5.0V, VBAT = 3.7V
RDS(ON) (mΩ)
Constant Charge Current (mA)
RISET=3.95kΩ
200
Figure 19. Trickle Charge Current vs Temperature
VIN = 5.0V, VBAT = 2.0V
VISET (V)
BAT Pin Output Voltage (V)
Trickle Charge Current (mA)
DET Dropout Voltage (mV)
ELECTRICAL CHARACTERISTICS
ELECTRICAL PERFORMANCE CURVES
-20
0
20
40
60
Temperature (°C)
80
Figure 18. Constant Charge Current vs Temperature
VIN = 5.0V, VBAT = 3.7V
200
-40
-20
0
20
40
60
Temperature (°C)
80
Figure 21. RDS(ON) vs Temperature
VBAT = 4.0V, ICHG = 500mA, IBAT = 400mA
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Analog Integrated Circuit Device Data
Freescale Semiconductor
4.20
VIN Pin Supply Current ( µA)
Recharge Voltage Threshold (V)
ELECTRICAL CHARACTERISTICS
ELECTRICAL PERFORMANCE CURVES
4.15
4.10
4.05
4.00
3.95
-40
-20
0
20
40
60
Temperature (°C)
80
1.00
0.75
0.50
0.25
0.00
-0.25
-0.50
-40
-20
0
20
40
60
Temperature (°C)
80
Figure 23. BAT Pin Supply Current vs Temperature
VBAT = 4.2V, VIN Pin Not Powered or Charger Disabled
2000
Charger Enabled
1500
1000
Charger Disabled
500
0
-40
-20
0
20
40
60
Temperature (°C)
80
Figure 24. VIN Pin Supply Current vs Temperature
VIN = 5.0V
DET Pin Output Voltage (V)
BAT Pin Supply Current (µA)
Figure 22. Recharge Voltage Threshold vs Temperature
RISET = 7.9kΩ, VIN = 5.0V
2500
5.00
4.95
4.90
4.85
4.80
4.75
4.70
-40
-20
0
20
40
60
Temperature (°C)
80
Figure 25. DET Pin Output Voltage vs Temperature
VIN = 5.2V, IDET = 10mA, IBAT = 0mA
34675
Analog Integrated Circuit Device Data
Freescale Semiconductor
11
FUNCTIONAL DESCRIPTION
INTRODUCTION
FUNCTIONAL DESCRIPTION
INTRODUCTION
The 34675 is a fully-integrated Li-Ion and Li-Polymer
battery charger, with a 4.85V/10mA linear regulator in a tiny
package. It uses current, voltage, and temperature control
loops to regulate the charge current. It has up to a 28V input
voltage rating, which makes the handheld device safe even
when connected to a wrong AC adapter. In addition, it
provides a 4.85V/10mA linear regulator.
The 34675 requires only two external capacitors and one
resistor to build a fully functional charger for space-limited
applications such as cell phones, Bluetooth accessories and
MP3 players. Its ultra high accuracy voltage (±0.7%) and
temperature limited charging current, offer additional battery
safety during charging.
The CC current can be programmed with an external
resistor (RISET). The voltage across this resistor is
proportional to the charge current, so the system can monitor
the charge current during the whole charge cycle. The EOC
threshold is preset to 10% of the CC mode current. For a
deeply discharged battery with a voltage lower than 2.7V, the
34675 charges the battery with a trickle-mode current, which
is 20% of the CC mode current.
The linear regulator provides 4.85V with 10mA capability.
The output is turned on when the input voltage is above the
POR threshold, but lower than the OVP threshold. The Linear
regulator is independent. It is not related to any signals of the
charger, including the enable input pin.
Two indication outputs make it easy to report the input
power status and the charge status to MCUs, or users via
LEDs.
FUNCTIONAL PIN DESCRIPTION
INPUT SUPPLY (VIN)
LINEAR REGULATOR OUTPUT (DET)
The supply input. This pin should be bypassed to ground
with a 1.0μF capacitor.
The linear regulator output. The output voltage is typically
4.85V. The output current capability is 10mA. Bypass this pin
to ground with a ceramic capacitor between 0.1μF and 1.0μF.
POWER PRESENT INDICATOR (PPR)
Open-drain logic output to indicate the status of the
supply input voltage. The PPR pin output is singularly
determined by the input voltage.The output is pulled
low if VIN is higher than VPOR. This pin is capable of
sinking at least 9.0mA of current to drive an LED
indicator.
CHARGE INDICATOR (CHG)
Open-drain logic output to indicate the charge status. The
output is low when the 34675 is charging, until the EOC
conditions are reached. This pin is capable of sinking at least
9.0mA of current to drive a LED indicator.
ENABLE (EN)
Active low enable logic Input. This pin is internally pulled to
ground by a weak current source. When left floating, the
charger is enabled. Pulling this pin to a high voltage
externally disables the charger.
GROUND (GND)
Ground.
CC MODE CURRENT SETTING AND CHARGE
CURRENT MONITOR (ISET)
The CC mode current, ICHG, is programmed by connecting
a resistor, RISET, between this pin and ground. When
charging in the CC mode, the voltage at this pin is 1.0V. The
voltage reduces proportionally as the charge current reduces
in the CV mode. During the whole charge cycle, the voltage
at this pin can be used to monitor the charge current, using
the following equation:
V ISET
I BAT = -------------- ⋅ I CHG
1.0V
where IBAT is the actual charge current, ICHG is the
programmed CC mode current, and VISET is the voltage of the
ISET pin during the whole charge cycle.
CHARGER OUTPUT (BAT)
Charger output pin. Connect this pin to the battery being
charged. Bypass to ground with a 2.2μF or higher capacitor.
EXPOSED PAD (EPAD)
Exposed pad. This must be soldered to the large ground
plane on the PCB to enhance the thermal conductivity. The
pad must be connected to GND electrically.
34675
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Analog Integrated Circuit Device Data
Freescale Semiconductor
FUNCTIONAL DESCRIPTION
FUNCTIONAL INTERNAL BLOCK DESCRIPTION
FUNCTIONAL INTERNAL BLOCK DESCRIPTION
MC34675 - Functional Block Diagram
Outputs
Integrated Supply
Internal Supply & Reference
Sensing & Control
VIN Monitor
Charge Control
Power MOSFET
End of Charge
Current Setting
Current Monitor
VIN - BAT Comparator
Die Temperature Feedback
Linear Regulator
Logic
Logic Control
Status Indication
Integrated Supply
Sensing & Control
Logic
Outputs
Figure 26. 34675 Functional Internal Block Diagram
INTEGRATED SUPPLY
Charge Control
Internal Supply and Reference
The charge control block controls the gate voltage of the
power MOSFET to regulate the charge current, the battery
voltage, or the die temperature. It can also completely turn off
the power MOSFET, to stop the current flow between the
input and the battery. Additionally, monitoring of the charge
current and the charger output voltage determines the tricklecharge mode and the recharge cycle.
This block steps down the high input voltage to a lower
voltage which powers all the internal blocks. In addition, this
block generates the reference voltage for the charge-control
block.
SENSING & CONTROL
VIN (Input Voltage) Monitor
The input voltage monitor block monitors the input voltage
for two thresholds, power-on-reset (POR) and over-voltage
protection (OVP). If the input is lower than the POR or higher
than the OVP threshold, this block outputs a logic signal to
disable the charger and the linear regulator.
Current Setting & Monitor
This block sets the charge current in the constant-current
mode, and monitors the actual charge current during the
whole charge cycle.
EOC (End of Charge)
The EOC block monitors the charge current and the
battery voltage for the EOC conditions. Once the EOC
conditions are reached, this block outputs a logic signal to
indicate the end of the charge.
VIN-BAT Comparator
The VIN-BAT comparator monitors the voltage difference
between the input voltage and the battery voltage. The input
voltage has to be higher than the battery voltage for the
charger to be enabled. If the input voltage falls below the
battery voltage, this block outputs a signal to disable the
charger to prevent the leakage current from the battery to the
input.
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13
FUNCTIONAL DESCRIPTION
FUNCTIONAL INTERNAL BLOCK DESCRIPTION
Die-Temperature feedback
The die temperature feedback block monitors the die
temperature. Once the die temperature reaches the
threshold temperature, this charge control block can reduce
the charge current to prevent further die temperature rise.
LOGIC
Logic Control and Status Indication
The logic control block determines the on and off of the
charger and indicates the charger status. It takes the signals
from the input voltage monitor, VIN-BAT comparator, EOC,
and the external enable signal, and determines the on and off
states as well as the charge status indication outputs of the
charger (CHG and PPR).
OUTPUTS
Power MOSFET
The power MOSFET passes the charging current from the
input to the output.
Linear Regulator
The linear regulator outputs a regulated 4.85V from the
input voltage with 10mA current capability. If the Input
Voltage Monitor detects that the input voltage is lower than
the POR or higher than the OVP threshold, the linear
regulator is disabled. No other signal can control the linear
regulator.
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FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
After the charge cycle is completed, the 34675
continues to regulate and monitor the output to 4.2V. If
a load is connected in parallel with the battery, the
34675 will ensure that the charger continues to supply
the charge current, even if the charge cycle is
completed. If the load current exceeds the preprogrammed CC mode current, the battery will supply
the additional current to the load, thereby reducing the
battery voltage. Once the battery voltage drops below
the recharge voltage, the 34675 returns to the fast
charge mode and indicates a logic low at the CHG pin.
CHARGE CYCLE
The 34675 uses the standard charge profile with trickle,
constant-current (CC), and constant-voltage (CV) charge
modes, as shown in Figure 27. Both the CC and the CV
charge modes are also called fast-charge mode. When the
input voltage rises above an internal power-on-reset
threshold, the PPR pin outputs a low voltage to indicate the
power-supply presence. The charger starts with the tricklecharge mode until the battery voltage is above 2.7V. The
CHG pin outputs logic low voltage at the beginning of the
trickle-charge mode. If the battery voltage is unable to rise
due to a battery failure, charging will remain in the tricklecharge mode. When the battery voltage reaches the 2.7V
threshold, the 34675 softly changes to the CC mode. The soft
transition minimizes the input-voltage drop and reduces the
requirement of the input decoupling capacitance. When the
battery voltage reaches 4.2V, the 34675 enters the CV mode
and regulates the output voltage at 4.2V. The charge current
decreases gradually in the CV mode. When the current drops
to the EOC current threshold, the 34675 outputs logic high
level at the CHG pin to indicate that the charging is
completed.
Trickle
Constant Current
1. VIN > VOVP
2. VIN-VBAT < VOS
3. EN pin is high
where VOS is the offset voltage for the comparator that
monitors the input and the battery voltages
Figure 29 shows the complete charge cycle state diagram.
ILOAD
>ICHG
Constant Voltage
4.2V
ICHG
2.7V
When one of the following three conditions happens, the
34675 stops charging and enters disable mode.
Battery
Voltage
100mV
Charge
Current
ITRKL
IEOC
TIME
CHG
TIME
Figure 27. Charge Profile
CHARGE CURRENT SETTING
An external resistor between the ISET pin and ground sets
the CC mode current with the following equation:
4000
I CHG = -------------R ISET
where RISET is the resistor between the ISET pin and ground
in Ω. ICHG is in Amps. In addition, the current out of the ISET
pin is proportional to the charge current. The system may
measure the ISET pin voltage to monitor the actual charge
current during the whole charging cycle, using the following
equation:
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15
FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
INPUT POWER PRESENCE INDICATOR
V ISET
I BAT = -------------- ⋅ I CHG
1.0V
CHARGE CURRENT LIMITATION
The charge current is limited by multiple factors.
When the voltage difference between the input and the
battery (VIN-VBAT) is low, (VIN - VBAT) / RDS(ON), where
RDS(ON) is the on resistance of the power MOSFET, may be
less than the programmed CC mode current ICHG. In this
case, the charge current is limited by (VIN - VBAT) / RDS(ON).
When the voltage difference between the input and the
battery is too high, the large power dissipation may lead to
the charge current thermal foldback operation, due to the die
temperature regulation. The charge current is reduced to
prevent further temperature rise (See Charge Current
Thermal Foldback section for more information).
When VIN is applied and the voltage is above the poweron-reset voltage threshold (VPOR), the PPR pin outputs a low
voltage to indicate the input-power presence. The PPR
output is only controlled by the input voltage. All other
functions, such as the EN pin, the over-voltage protection,
and the VIN-BAT comparator, do not affect the PPR output.
The PPR pin is capable of sinking at least 9.0mA of current
when outputting a low voltage to drive an external LED.
CHARGE STATUS INDICATORS
The 34675 has one charge-status indicator, CHG. CHG
outputs a low voltage when the charger is enabled and the
charging is in progress. When the charge cycle completes,
CHG outputs high-impedance. If the charger is disabled or
the input voltage is out of the power-good range, the CHG pin
outputs a high-impedance as well. The CHG pin has at least
9.0mA current-sinking capability to drive an external LED, the
same as the PPR pin.
DC INPUT VOLTAGE
CHARGE CURRENT THERMAL FOLDBACK
The 34675 accepts up to a 28V DC input. When all of the
following conditions are satisfied, the input is in a power-good
range for the charger to start charging. The conditions
include:
An internal thermal feedback loop begins to reduce the
charge current, when the die temperature reaches 120°C, to
prevent further temperature rise. This feature protects the
34675 from over-temperature failure, and allows the user to
push the limits of the power-handling capability of a given
circuit board, without the risk of damaging the 34675. The
charge current can be programmed according to the typical
(not the worst case) ambient temperature, with the assurance
that the charger will automatically reduce the current in worst
case conditions.
1. VIN > VPOR
2. VIN -VBAT > VOS
3. VIN < VOVP
where VOS is the offset voltage for the comparator that
monitors the input and the battery voltages. The VOS is for
preventing the reverse leakage current from the battery when
the external power supply is off. VOVP is the over-voltage
protection threshold. When the DC input voltage is above the
over-voltage protection threshold, the charger is disabled
internally. The 28V input voltage rating eliminates the need of
any additional input over-voltage protection circuitry.
CHARGE-ENABLE INPUT
The charge-enable input, EN, has a weak internal pulldown current. Driving it to a low voltage, leaving it float, or
shorting it to ground, will enable the charger if the input
voltage is in the power-good range. Whenever the EN pin is
driven to a high voltage, the charger is disabled. When the
charger is disabled, the BAT pin does not output voltage and
current, the leakage current into the BAT pin is less than
1.0μA, the output of the CHG pin is high, and the voltage at
the ISET pin is zero. If the input voltage is in the power-good
range when the charger is disabled, the output of the PPR is
still low to indicate the input voltage status and the DET pin
outputs voltage as well.
LINEAR REGULATOR
The linear regulator provides a 4.85V output with 10mA
current capability. The output is turned on when the input
voltage is above the POR threshold but lower than the OVP
threshold. The output is independent of any other signals in
the charger, such as the enable (EN) input.
When the input reaches the rising POR threshold, the DET
output starts to output a voltage, but is in the dropout mode.
The output voltage is determined by the dropout voltage. As
the input voltage rises above the regulation voltage, the
output is regulated at 4.85V. When the input voltage further
rises above the OVP rising threshold, the linear regulator is
turned off, and the output voltage drops to zero with an
internal 200kΩ pull-down resistor. The output voltage
resumes to 4.85V when the input voltage falls below the OVP
falling threshold. The output voltage versus the input voltage
is shown in Figure 28, where the VPORR and VPORF are the
POR rising and falling threshold. The VOVPR and VOVPF are
the OVP rising and falling threshold. An output decoupling
capacitor of 0.1μF to 1.0μF is required between the DET pin
and ground for the stability of the linear regulator.
34675
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Analog Integrated Circuit Device Data
Freescale Semiconductor
FUNCTIONAL DEVICE OPERATION
CHARGE STATE DIAGRAM
VIN
VOVPR
VPORR
VOVPF
4.85V
VDET
VPORF
Figure 28. DET Pin Output Voltage vs Input Voltage
CHARGE STATE DIAGRAM
PWR OFF
VIN<VPOR
Charger: OFF
VIN>VPOR
EN=high
or VIN>VOVP
or VIN<VBAT+VOS
SHUTDOWN
Charger: OFF
EN=low
and VIN<VOVP
and VIN>VBAT+VOS
VBAT < 2.7V
TRICKLE
CHARGE
VBAT > 2.7V
Charger: ON
VBAT < 2.7V
FAST CHARGE
Charger: ON
VBAT=4.2V
and IBAT < IEOC
VBAT<4.10V
CHARGE
COMPLETE
Charger: ON
Figure 29. Charge Cycle State Diagram
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17
TYPICAL APPLICATIONS
APPLICATION INFORMATION
TYPICAL APPLICATIONS
APPLICATION INFORMATION
INPUT CAPACITOR
the power MOSFET. The worst case of the RDS(ON) is
475mΩ. The input voltage should be at least higher than
VBAT + ICHG x 475mΩ, to guarantee the programmed CC
mode current.
The input capacitor is used to reduce the input voltage
transient, which may cause instability when the input voltage
is near VBAT+VOS. A 1.0μF, X5R, 16V rated ceramic
capacitor is recommended for most applications.
USE DET AS POWER PRESENCE INTERRUPT
OUTPUT CAPACITOR
Some cell phone designs require an active-high power
presence indication signal, to turn on an originally-off phone,
when an ac/dc adapter is plugged in. The DET output can be
used for such a purpose, instead of the PPR pin.
For stable operation, an X5R ceramic capacitor with a
minimum 2.2μF nominal value is recommended at the
charger output. Depending on the load transient current, a
larger capacitance may be required.
The linear regulator is designed to be stable with a ceramic
capacitor of 0.1μF through 1.0μF. An X5R ceramic capacitor
of 0.22μF is recommended for the application.
THERMAL CONSIDERATIONS
The 34675 is available in a tiny 2x3 thermally-enhanced
UDFN package. A careful thermal design must be
considered. The exposed pad needs to be well soldered to a
large copper ground plane on the component layer. If the
component layer is space limited and does not allow for a
large copper plane, the thermal pad must be connected to
other ground layers through a via array. This allows the
34675 to charge the battery with the maximum current, while
minimizing the die temperature.
CC MODE CURRENT SETTING
The CC mode current can be programmed by the external
resistor, RISET. A 1% accuracy resistor is recommended to
guarantee 6% current accuracy.
DROPOUT VOLTAGE
If the DC input voltage is too low, it may not maintain the
programmed charge current due to the voltage dropout over
TYPICAL APPLICATIONS
CHARGER IN THE HANDHELD SYSTEM
the CHG pin to the MCU. The MCU can also monitor the
charge current by measuring the voltage at the ISET pin. The
linear regulator powers subsystems, such as a USB
transceiver, that require a voltage higher than 4.5V.
Figure 30 is the typical application circuit.
When the charger is used in handheld systems with MCU
control, the 34675 uses PPR to report the DC input status to
the MCU. After the MCU pulls the EN pin to a low logic level
to start charging, the 34675 reports the charge status through
DC
Input
BAT
VIN
1.0µF
2.2µF
VIO
Li+
GND
100K
MC34675
ISET
100K
CHG
MCU
PPR
8.06K
EN
OFF
ON
DET
USB
Xcvr
0.22µF
Figure 30. Li+ Battery Charger in Handheld System
34675
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Analog Integrated Circuit Device Data
Freescale Semiconductor
PACKAGING
PACKAGE DIMENSIONS
PACKAGING
PACKAGE DIMENSIONS
For the most current package revision, visit www.freescale.com and perform a keyword search using the “98A” listed below.
EP SUFFIX
8-PIN
98ASA10774D
REVISION 0
34675
Analog Integrated Circuit Device Data
Freescale Semiconductor
19
PACKAGING
PACKAGING DIMENSIONS (CONTINUED)
PACKAGING DIMENSIONS (CONTINUED)
EP SUFFIX
8-PIN
98ASA10774D
REVISION 0
34675
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Analog Integrated Circuit Device Data
Freescale Semiconductor
PACKAGING
PACKAGING DIMENSIONS (CONTINUED
PACKAGING DIMENSIONS (CONTINUED
EP SUFFIX
8-PIN
98ASA10774D
REVISION 0
34675
Analog Integrated Circuit Device Data
Freescale Semiconductor
21
PACKAGING
34675
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Analog Integrated Circuit Device Data
Freescale Semiconductor
REVISION HISTORY
REVISION HISTORY
REVISION
DATE
DESCRIPTION OF CHANGES
1.0
4/2008
•
Initial Release
2.0
4/2008
•
Added Tape & Reel positioning drawing
3.0
4/2008
•
Deleted Tape & Reel positioning drawing
34675
Analog Integrated Circuit Device Data
Freescale Semiconductor
23
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MC34675
Rev. 3.0
4/2008
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