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PDF LTC4011 Data sheet ( Hoja de datos )
| Número de pieza | LTC4011 | |
| Descripción | High Efficiency Standalone Nickel Battery Charger | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Electrical Specifications Subject to Change
LTC4011
High Efficiency Standalone
Nickel Battery Charger
FEATURES
DESCRIPTIO
■ Complete NiMH/NiCd Charger for 1 to 16 Cells
■ No Microcontroller or Firmware Required
■ 550kHz Synchronous PWM Current Source Controller
■ No Audible Noise with Ceramic Capacitors
■ PowerPathTM Control Support
■ Programmable Charge Current: 5% Accuracy
■ Wide Input Voltage Range: 4.5V to 34V
■ Automatic Trickle Precharge
■ –∆V Fast Charge Termination
■ Optional ∆T/∆t Fast Charge Termination
■ Automatic NiMH Top-Off Charge
■ Programmable Timer
■ Automatic Recharge
■ Multiple Status Outputs
■ Micropower Shutdown
■ 20-Lead Thermally Enhanced TSSOP Package
U
APPLICATIO S
■ Integrated or Standalone Battery Charger
■ Portable Instruments or Consumer Products
■ Battery-Powered Diagnostics and Control
■ Back-Up Battery Management
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
PowerPath is a trademark of Linear Technology Corporation.
The LTC®4011 provides a complete, cost-effective nickel
battery fast charge solution in a small package using few
external components. A 550kHz PWM current source
controller and all necessary charge initiation, monitoring
and termination control circuitry are included.
The LTC4011 automatically senses the presence of a DC
adapter and battery insertion or removal. Heavily dis-
charged batteries are precharged with a trickle current.
The LTC4011 can simultaneously use both –∆V and ∆T/∆t
fast charge termination techniques and can detect various
battery faults. If necessary, a top-off charge is automati-
cally applied to NiMH batteries after fast charging is
completed. The IC will also resume charging if the battery
self-discharges after a full charge cycle.
All LTC4011 charging operations are qualified by actual
charge time and maximum average cell voltage. Charging
may also be gated by minimum and maximum tempera-
ture limits. NiMH or NiCd fast charge termination param-
eters are pin-selectable.
Integrated PowerPath control support ensures that the
system remains powered at all times without allowing load
transients to adversely affect charge termination.
TYPICAL APPLICATIO
FROM
ADAPTER
4.5V TO 34V
3k
20k
49.9k
2A NiMH Battery Charger
TO
SYSTEM
10µF LOAD
INFET
VCC
FAULT TGATE
CHRG
TOC
READY BGATE
PGND
LTC4011
DCIN SENSE
TIMER
10µH
0.05Ω
BAT
GND
CHEM
VRT
INTVDD
VCDIV
VCELL
VTEMP
10k
10k
10µF
0.1µF
0.033µF
0.068µF 30.9k
10.7k
2-CELL
NiMH PACK
WITH 10k NTC
(2AHr)
4011 TA01a
DataSheet4 U .com
Typical NiMH Charge Cycle at 1C
1.60 42
1.55 40
1.50
SINGLE CELL
1.45 VOLTAGE
38
36
1.40
1.35
1.30
1.25
0
BATTERY
TEMPERATURE
34
CHARGE
CURRRENT
2A
1A
TOP OFF
32
30
20 40 60 80
TIME (MINUTES)
28
100
4011 TA01b
4011p
1
1 page  
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TYPICAL PERFOR A CE CHARACTERISTICS
LTC4011
PowerPath Switching
12
8
DCIN OPEN
4
VCC
0 INFET
DCIN
100µs/DIV
4011 G09
DC674A WITH 1kΩ SYSTEM LOAD AND 20kΩ
DCIN SHUNT, CHARGER PAUSED
NiCd Charge at 1C
1.65
1.60
36
34
1.55
1.50
1.45
1.40
1.35
1.30
0
SINGLE CELL
VOLTAGE
32
30
BATTERY
TEMPERATURE
28
26
1A
CHARGE CURRENT
24
22
20 40 60 80
TIME (MINUTES)
4011 G01
4 Series NiCd 1300mAhr
1.75
4 SERIES NiCd 1300mAhr
1.70 SC CELLS CHARGED AT 2C
1.65
SINGLE CELL
VOLTAGE
1.60
55
50
45
40
1.55
BATTERY
35
TEMPERATURE
1.50 3A 30
1.45 2A 25
CHARGE CURRENT
1.40 1A 20
1.35
0
10 20 30
TIME (MINUTES)
15
40
4011 G02
NiMH Charge at 0.5C
1.60
4 SERIES NimH 2100mAHr
AA CELLS CHARGED AT 0.5C
1.55
SINGLE CELL
VOLTAGE
1.50
45
40
35
1.45 30
BATTERY
TEMPERATURE
1.40 1A 25
CHARGE CURRENT
1.45 0.5A 20
1.30
0
TOP OFF
15
20 40 60 80 100 120 140 160 180 200
TIME (MINUTES)
4011 G03
Charger Efficiency at DCIN = 20V,
IOUT = 2A
100
95
90
85
80
75
70
65
60
0 2 4 6 8 10 12 14 16 18 20
BATTERY VOLTAGE (V)
4011 G04
Charge Current Accuracy
0
FAST CHARGE
–2
–4
VCC = 12V
BAT = 4.8V
–6
–8 PRECHARGE
–10
–12
0
10 20 30 40
TEMPERATURE (°C)
50
4011 G05
Charger Soft-Start
10
5
TGATE
5
0
BGATE
FAST CHARGE CURRENT
PRECHARGE CURRENT
2
1
0
200µs/DIV
4011 G06
Fast Charge Current Line
Regulation
3
BAT = 4.8V
2
1
0 50°C
25°C
–1
0°C
–2
–3
6
10 14 18 22 26 30
VCC (V)
4011 G07
Fast Charge Current Output
Regulation
3
VCC = 20V
2
1
0 50°C
25°C
–1
0°C
–2
–3
0
4
8 12 16
BAT (V)
4011 G08
DataSheet4 U .com
4011p
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OPERATIO
Top-Off Charge State
If NiMH fast charge termination occurs because the ∆T/∆t
limit is exceeded after an initial period of tMAX/12 has ex-
pired, the LTC4011 enters the top-off charge state. Top-off
charge is implemented by sourcing one-tenth the pro-
grammed charge current for tMAX/3 minutes to ensure that
100% charge has been delivered to the battery. The CHRG
and TOC status outputs are active during the top-off state.
If NiCd cells have been selected with the CHEM pin, the
LTC4011 never enters the top-off state.
Automatic Recharge State
Once charging is complete, the automatic recharge state
is entered to address the self-discharge characteristics of
nickel chemistry cells. The charge status outputs are
inactive during automatic recharge, but VCDIV remains
switched to GND to monitor the average cell voltage. If the
VCELL voltage drops below 1.325V without falling below
350mV, the charge timer is reset and a new fast charge
cycle is initiated.
The internal termination algorithms of the LTC4011 are
adjusted when a fast charge cycle is initiated from auto-
matic recharge, because the battery should be almost fully
charged. Voltage-based termination is enabled immedi-
ately and the NiMH ∆T/∆t limit is fixed at a battery
temperature rise of 1°C/minute.
Fault State
As discussed previously, the LTC4011 enters the fault
state based on detection of invalid battery voltages during
various charging phases. The IC also monitors the regu-
lation of the PWM control loop and will enter the fault state
if this is not within acceptable limits. Once in the fault state,
the battery must be removed or DC input power must be
cycled in order to initiate further charging. In the fault
state, the FAULT output is active, the READY output is
inactive, charging stops and the charge indicator outputs
are inactive. The VCDIV output remains connected to GND
to allow detection of battery removal.
Note that the LTC4011 also uses the FAULT output to
indicate that charging is suspended due to invalid battery
or internal die temperatures. However, the IC does not
enter the fault state in these cases and normal operation
DataSheet4 U .com
LTC4011
will resume when all temperatures return to acceptable
levels. Refer to the Status Outputs section for more detail.
Insertion and Removal of Batteries
The LTC4011 automatically senses the insertion or re-
moval of a battery by monitoring the VCELL pin voltage.
Should this voltage fall below 350mV, the IC considers the
battery to be absent. Removing and then inserting a
battery causes the LTC4011 to initiate a completely new
charge cycle beginning with charge qualification.
External Pause Control
After charging is initiated, the VTEMP pin may be used to
pause operation at any time. When the voltage between
VTEMP and GND drops below 200mV, the charge timer
pauses, fast charge termination algorithms are inhibited
and the PWM outputs are disabled. The status and VCDIV
outputs all remain active. Normal function is fully restored
from the previous state when pause ends.
Status Outputs
The LTC4011 open-drain status outputs provide valuable
information about the IC’s operating state and can be
used for a variety of purposes in applications. Table 1
summarizes the state of the four status outputs and the
VCDIV pin as a function of LTC4011 operation. The status
outputs can directly drive current-limited LEDs termi-
nated to the DC input. The VCDIV column in Table 1is
strictly informational. VCDIV should only be used for the
VCELL resistor divider, as previously discussed.
Table 1. LTC4011 Status Pins
READY FAULT CHRG TOC VCDIV
Off Off Off Off Off
CHARGER STATE
Off
On Off Off Off On
Ready to Charge
(VTEMP Held Low)
or Automatic Recharge
On Off On Off On Precharge or Fast Charge
(May be Paused)
On Off On On On NiMH Top-Off Charge
(May be Paused)
On On On or Off On or Off On
Temperature Limits
Exceeded
Off On Off Off On Fault State (Latched)
4011p
11
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| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet LTC4011.PDF ] | |
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