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ADP3801 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer ADP3801
Beschreibung High Frequency Switch Mode Dual Li-Ion Battery Chargers
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 20 Seiten
ADP3801 Datasheet, Funktion
a
FEATURES
Stand-Alone Li-Ion Battery Chargers
High End-of-Charge Voltage Accuracy
؎0.4% @ +25؇C
؎0.75% @ –10؇C to +70؇C
Intelligent End-of-Charge Output Signal
Pin Programmable Cell Number Select
On Chip 3.3 V LDO Regulator
Programmable Charge Current with High Side Sense
Softstart Charge Current
Undervoltage Lockout
Drives External PMOS
؎10% Adjustable End-of-Charge Voltage
Charges NiCad, NiMH (with External Controller)
PWM Oscillator Frequency:
ADP3801: 200 kHz
ADP3802: 500 kHz
APPLICATIONS
Fast Chargers
Universal Chargers
Cellular Phones
Portable Computers
Portable Instrumentation
Desktop Chargers
Personal Digital Assistants
GENERAL DESCRIPTION
The ADP3801 and ADP3802 are complete battery charging
ICs. The devices combine a high accuracy final battery voltage
control with a constant charge current control and an on-board
Low Drop-Out Regulator (LDO). The accuracy of the final
battery voltage control is guaranteed to ± 0.75% to safely charge
Li-Ion batteries. An internal multiplexer allows the alternate
charging of two separate battery stacks. The final voltage is pin
programmable to one of three Li-Ion options: 4.2 V (one Li-Ion
cell), 8.4 V (two Li-Ion cells), or 12.6 V (three Li-Ion cells).
Paired with an external microcontroller for charge termination,
the ADP3801/ADP3802 works as a fast charger for NiCad/
NiMH batteries or as a universal charger for all three battery
chemistries. In addition, a pin is provided for changing the final
battery voltage by up to ± 10% to adjust for variations in battery
chemistry from different Li-Ion manufacturers without loss of
accuracy in the final battery voltage.
High Frequency Switch Mode
Dual Li-Ion Battery Chargers
ADP3801/ADP3802
FUNCTIONAL BLOCK DIAGRAM
VCC
DRV EOC CS+ CS– A/B
VL
SD
RESET
LDO +
GATE
REFERENCE DRIVE
CURRENT
LOOP
AMP + EOC
COMPARATOR
A/B
SELECT
MUX
SHUTDOWN
UVLO
+
RESET
PWM
SD\UVLO
ADP3801/ADP3802
FINAL BATTERY
VOLTAGE
PROGRAM
(4.2, 8.4, 12.6)
VOLTAGE
LOOP
AMP
BATTERY
VOLTAGE
ADJUST
؎10%
BATA
BATB
ISET
PROG
GND
COMP
ADJ
68H
40m
VIN
3.3V
VCC DRV
VL
EOC
CS+ CS–
A/B
BATA
SD
RESET
ADP3801/ADP3802
BATB
ISET
PROG
GND
COMP
ADJ
BATA
BATB
Figure 1. 4 Amp Dual Battery Charger
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 1998






ADP3801 Datasheet, Funktion
ADP3801/ADP3802
0.4
TA = +25؇C
0.3
0.2
0.1
0 1 2 3 4 5 6 7 8 9 10
LOAD CURRENT – mA
Figure 11. LDO Dropout Voltage vs.
Load Current
0
VCC = 10V
–20
TA = +25؇C
CLDO = 1F
–40
–60
–80
–100
1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 1.0E+06
FREQUENCY – Hz
Figure 12. LDO PSRR vs. Frequency
215
ADP3801
VCC = 10V
205
195
185
175
–40 –20
0 20 40 60
TEMPERATURE – ؇C
80 100
Figure 13. Oscillator Frequency vs.
Temperature
100
VCC = 10V
TA = +25؇C
80
60
40
20
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
VCOMP – Volts
Figure 14. Duty Cycle vs. COMP Pin
Voltage
12
10
8
6
4
2
0
1
CH1 2.00V
VCC = 10V
CL = 1nF
TA = +25؇C
250ns/DIV
M 250ns CH1
TIME – ns
9.40V
Figure 15. DRV Rise and Fall Times
0.4
VCC = 10V
0.3
0.2
0
–40 –20
0 20 40 60
TEMPERATURE – ؇C
80 100
Figure 16. DRV High Saturation Volt-
age vs. Temperature
3.9
VCC = 10V
3.8
3.7
3.6
3.5
–40 –20
0 20 40 60
TEMPERATURE – ؇C
80 100
Figure 17. DRV Output Low Voltage
with VCC = 10 V vs. Temperature
5.5
5.0 TA = +85؇C
TA = +25؇C
4.5
4.0
3.5
4
TA = –40؇C
NOT SWITCHING
SD = ON
8 12 16
SUPPLY VOLTAGE – Volts
20
Figure 18. Power Supply Current vs.
Supply Voltage @ Three Temperatures
15
VCC = 10V
13
TA = +25؇C
50% DUTY CYCLE
11
ADP3802
9
7
ADP3801
5
0 0.5 1.0 1.5 2.0 2.5
CAPACITIVE LOAD – nF
Figure 19. Power Supply Current vs.
Capacitive Load on DRV
–6– REV. 0

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ADP3801 pdf, datenblatt
ADP3801/ADP3802
SD results in shutdown. All internal circuitry is shut off except
for the LDO and the reference, and the supply current is typi-
cally 110 µA. When SD returns high, the part resumes full op-
eration. The compensation capacitor at the COMP node is
discharged during shutdown, so the part will resume operation
in soft-start mode.
Undervoltage Lockout—UVLO
The internal Undervoltage Lockout (UVLO) circuit monitors
the input voltage and keeps the part in shut-down mode until
VCC rises above 3.9 V. During UVLO, the LDO and reference
are still active, but the analog front end, the oscillator, and the
gate drive are off. UVLO helps to prevent the circuitry from
entering an unknown state that could incorrectly charge a battery.
To prevent oscillation around VCC = 3.9 V, the UVLO cir-
cuitry has built-in hysteresis. Once the part is on, the UVLO
circuitry does not shut it off until the LDO enters dropout.
Because the dropout voltage depends on the LDO’s load, the
UVLO trip point-off also depends on the load. Refer to Figure 8
for a graph of the UVLO trip point-off versus LDO load.
RESET
When the power is first applied to the ADP3801/ADP3802, the
RESET pin is held at ground by an external 1 Mresistor. It
remains low until the LDO output voltage rises to above 80% of
its final value. When this threshold is reached, the RESET pin is
pulled high. The internal RESET comparator includes about
150 mV of hysteresis to avoid oscillation around the threshold.
Supply Considerations
The guaranteed operating supply voltage range of the ADP3801/
ADP3802 is from 4 V to 20 V, and it typically consumes 5.0 mA
of quiescent current when not switching. However, the part
needs at least 2 V of headroom between VCC and the voltage
on the CS+ and CS– pins. This is for the common-mode range
on the current sense amplifier. In applications where the input
supply does not offer enough headroom, the circuits in Figures
32 and 33 can be used as explained in the section on low over-
head charging.
Overtemperature Shutdown
The ADP3801/ADP3802 has an on-chip temperature detector
to shut the part down when the die temperature reaches typi-
cally +160°C. Such a condition could occur with a short-circuit
on the LDO or a short on the DRV pin. In either case, the op-
eration of the charger will stop and the DRV pin will be pulled
high. With approximately +10°C hysteresis, the overtemperature
shutdown releases at typically +150°C. These temperatures are
higher than the absolute maximum ratings for the die, and are
included as a safety feature only.
Li-Ion Battery Charger
The ADP3801 and ADP3802 are ideally suited for a single or
dual Li-Ion batterypack charger. They combine 200 kHz or
500 kHz switching with a PMOS pass transistor drive to realize
a Buck topology CCCV charger. The following discussion goes
through the complete design of a charger using the ADP3801.
This information also applies to the ADP3802.
Charger Specifications
Battery: 3 Series Cell Li-Ion Pack.
Input Voltage: VIN = 15 V dc to 20 V dc.
Final Battery Voltage: VBAT = 12.6 V.
Charge Current: ICHARGE = 4.0 A (for VO = 0 V to 12.6 V)
Circuit Topology
The complete Buck charger circuit is shown in Figure 24. The
dc-source voltage can be supplied from an ac/dc adaptor or an
external dc/dc supply.
(+15V TO +20V)
VIN
0.1F
Si4463
33H
210F
25V
MBRD835 1k
RCS
40mMBRD835
140F
25V
4.3k
4.3k
BATA
12.6VMAX
RESET
SD
VL = +3.3V
1.0F
EOC
1M
100k
24k
20k
C7
2.2nF
DRV
RESET
VCC
VL
SD
CS–
CS+
ISET
ADP3801/
ADP3802
TOP VIEW
(Not to Scale)
GND
A/B
BATA
BATB
PROG
ADJ
EOC
COMP
56
4.7F
C9
2.2nF
100k
200k
100k
Figure 24. Li-Ion Battery Charger
–12–
REV. 0

12 Page





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