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Linear Technology LTC4000 Datasheet

High voltage high current controller for battery charging and power management
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FeaTures
Complete High Performance Battery Charger When
n
Paired with a DC/DC Converter
Wide Input and Output Voltage Range: 3V to 60V
n
Input Ideal Diode for Low Loss Reverse Blocking
n
and Load Sharing
Output Ideal Diode for Low Loss PowerPath™ and
n
Load Sharing with the Battery
Instant-On Operation with Heavily Discharged
n
Battery
Programmable Input and Charge Current:
n
±1% Accuracy
±0.25% Accurate Programmable Float Voltage
n
Programmable C/X or Timer Based Charge
n
Termination
NTC Input for Temperature Qualified Charging
n
28-Lead 4mm × 5mm QFN or SSOP Packages
n
applicaTions
High Power Battery Charger Systems
n
High Performance Portable Instruments
n
Industrial Battery Equipped Devices
n
Notebook/Subnotebook Computers
n
Typical applicaTion
48V to 10.8V at 10A Buck Converter Charger for Three LiFePO
LT3845A
IN
15V TO 60V
SHDN
5m
RST
CLN
IN
1µF
1.10M
VM
100k
3.0V
ENC
CHRG
FLT
IIMON
10nF
IBMON
10nF
Si7135DP
OUT
V
C
100µF
14.7k
47nF
ITH
CC
IID
IGATE
CSP
BGATE
LTC4000
TMR
CL
CX
GND BIAS
24.9k
22.1k
0.1µF
For more information
High Voltage High Current
Controller for Battery Charging
and Power Management
DescripTion
The
LTC
4000
is a high voltage, high performance controller
®
that converts many externally compensated DC/DC power
supplies into full-featured battery chargers.
Features of the LTC4000's battery charger include: accurate
(±0.25%) programmable float voltage, selectable timer or
current termination, temperature qualified charging using
an NTC thermistor, automatic recharge, C/10 trickle charge
for deeply discharged cells, bad battery detection and
status indicator outputs. The battery charger also includes
precision current sensing that allows lower sense voltages
for high current applications.
The LTC4000 supports intelligent PowerPath control. An
external PFET provides low loss reverse current protec-
tion. Another external PFET provides low loss charging
or discharging of the battery. This second PFET also
facilitates an instant-on feature that provides immediate
downstream system power even when connected to a
heavily discharged or short faulted battery.
The LTC4000 is available in a low profile 28-lead 4mm ×
5mm QFN and SSOP packages.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
Cells
4
V
OUT
12V, 15A
1.15M
5m
CSN
Si7135DP
BAT
OFB
127k
FBG
V
133k
BAT
10.8V FLOAT
BFB
10A MAX CHARGE
1.13M
CURRENT
NTC
10k
3-CELL LiFePO
10k
BATTERY PACK
1µF
4000 TA01a
NTHS0603
N02N1002J
www.linear.com/LTC4000
LTC4000
Charge Current and V
vs V
During a Charge Cycle
BAT
12
I
CHARGE
10
8
V
OUT
6
4
2
I
CHARGE
0
6
7
8
9
V
(V)
BAT
4
Profile
OUT
11
V
OUT
10.5
10
9.5
9
8.5
8
10
11
12
4000 TA01b
4000fb
1

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Summary of Contents for Linear Technology LTC4000

  • Page 1 5mm QFN and SSOP packages. Industrial Battery Equipped Devices Notebook/Subnotebook Computers L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
  • Page 2 LTC4000 absoluTe MaxiMuM raTings (Note 1) IN, CLN, IID, CSP, CSN, BAT ....... –0.3V to 62V BIAS ..........–0.3V to Min (6V, V IN-CLN, CSP-CSN ..........–1V to 1V IBMON ........–0.3V to Min (V BIAS OFB, BFB, FBG ........... –0.3V to 62V ITH ...............
  • Page 3 LTC4000 elecTrical characTerisTics denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at T = 25°C. V = 3V to 60V unless otherwise noted (Notes 2, 3). SYMBOL PARAMETER CONDITIONS UNITS Input Supply Operating Range...
  • Page 4 LTC4000 elecTrical characTerisTics denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at T = 25°C. V = 3V to 60V unless otherwise noted (Notes 2, 3). SYMBOL PARAMETER CONDITIONS UNITS Charge Termination CX Pin Pull-Up Current = 0.1V...
  • Page 5 , in °C) and power dissipation (P , in Watts) according to the following formula: Note 2: The LTC4000 is tested under conditions such that T ≈ T . The LTC4000E is guaranteed to meet specifications from 0°C to 85°C junction + (P •...
  • Page 6 LTC4000 Typical perForMance characTerisTics Input Quiescent Current and Battery Float Voltage Feedback, Output Battery Quiescent Current Over Battery Only Quiescent Current Voltage Regulation Feedback and VM Temperature Over Temperature Falling Threshold Over Temperature 1.20 = 15V = 15.5V 1.19 = 60V 1.18...
  • Page 7 LTC4000 Typical perForMance characTerisTics Charge Termination Time with 0.1µF NTC Thresholds Over PowerPath Forward Voltage Timer Capacitor Over Temperature Temperature Regulation Over Temperature NTC(COLD) = 15V = 3V NTC(OPEN) = 60V NTC(HOT) –60 –40 –20 0 40 60 80 –60 –40...
  • Page 8 LTC4000 pin FuncTions (QFN/SSOP) VM (Pin 1/Pin 25): Voltage Monitor Input. High impedance ENC (Pin 5/Pin 1): Enable Charging Pin. High impedance input to an accurate comparator with a 1.193V threshold digital input pin. Pull this pin above 1.5V to enable charg- (typical).
  • Page 9 This allows the instant-on feature, providing an immedi- voltage output. Use this pin to bias the resistor divider to ate valid voltage level at the output when the LTC4000 is set up the voltage at the NTC pin. charging a heavily discharged battery. Once the voltage NTC (Pin 14/Pin 10): Thermistor Input.
  • Page 10 Battery Ideal Diode Cathode. Connect a sense resistor (3V to 60V). To ensure that the input PMOS is turned off between this pin and the CSP pin. The LTC4000 senses when the IN pin voltage is not within its operating range, the voltage across this sense resistor and regulates it to connect a 10M resistor from this pin to the CSP pin.
  • Page 11 1.136V BIAS BIAS BFB1 BFB2 TOO COLD 1.109V – NTC FAULT LOGIC – BIAS TOO HOT – 5µA – 10mV – BIAS BATTERY PACK 2µA OSCILLATOR CHRG 4000 BD Figure 1. LTC4000 Functional Block Diagram 4000fb For more information www.linear.com/LTC4000...
  • Page 12 GND pins, and a corresponding resistor from the BIAS (using a resistor divider from CSP to FBG via OFB) is not pin to the NTC pin. The LTC4000 also provides a charging exceeded. The LTC4000 also provides monitoring pins status indicator through the FLT and the CHRG pins.
  • Page 13 In addition to the input current regulation loop, the to the system load as needed. If the system load can be LTC4000 regulates charge current, battery voltage and completely supplied from the input, the battery PMOS turns output voltage.
  • Page 14 4000 FO3 Battery Instant-On and Ideal Diode Figure 3. Charge Current Regulation Loop The LTC4000 controls the external PMOS connected to the Battery Voltage Regulation BGATE pin with a controller similar to the input ideal diode controller driving the IGATE pin. When not charging, the...
  • Page 15 BIAS CONVERTER When charging is paused, the external charging PMOS turns off and charge current drops to zero. If the LTC4000 is charging in the constant voltage mode and the charge – termination timer is enabled, the timer pauses until the thermistor indicates a return to a valid temperature.
  • Page 16 LTC4000 applicaTions inForMaTion Input Ideal Diode PMOS Selection pin to the CSP pin. Therefore, for a 10M R resistor IGATE and assuming a 10V V , the additional forward voltage GSON The input external PMOS is selected based on the expected regulation is ∆V...
  • Page 17 LTC4000 applicaTions inForMaTion The voltage on the IIMON pin can be filtered further by putting reduce the AC content of the current through the sense a capacitor on the pin (C ). The voltage on the IIMON resistor (R ). Where the highest accuracy is important,...
  • Page 18 For example, a typical capacitance of 1nF requires a capaci- tor greater than 100nF connected to the CX pin to ensure The LTC4000 also features bad battery detection. This proper C/X termination behavior. detection is disabled if the TMR pin is grounded or tied to BIAS.
  • Page 19 LTC4000 applicaTions inForMaTion Battery Instant-On and Ideal Diode External PMOS On the other hand, when the battery voltage is above the Consideration low battery threshold but still below the instant-on thresh- old, the power dissipation can be calculated as follows:...
  • Page 20 LTC4000 applicaTions inForMaTion Similar to the input external PMOS, the charging external In the typical application, V is set higher than V FLOAT PMOS must be able to withstand a gate to source voltage to ensure that the battery is charged fully to its intended...
  • Page 21 NTC thermistor at 25°C ground. Therefore, intuitively this resistor will move the hot (R25). In this simple setup, the LTC4000 will pause charg- threshold to a hotter temperature and the cold threshold ing when the resistance of the NTC thermistor drops to to a colder temperature.
  • Page 22 The BIAS Pin in series with R3 between the BIAS pin and the NTC pin. For ease of use the LTC4000 provides a low dropout volt- This PTC resistor also needs to be thermally coupled with age regulator output on the BIAS pin. Designed to provide the battery.
  • Page 23 Once these are typical sinking capability of the LTC4000 at the ITH pin is 1mA at 0.4V with a maximum voltage range of 0V to 6V.
  • Page 24 LTC4000 applicaTions inForMaTion SWITCHING CONVERTER 0.015µF 1500pF SCOPE GROUND 1000µF CLIP (OBSERVE POLARITY) LTC4000 BGATE GENERATOR f = 50Hz 4000 F12 Figure 12. Empirical Loop Compensation Setup Generator frequency is set at 50Hz. Lower frequencies of the second probe connected to exactly the same place may cause a blinking scope display and higher frequen- as channel A ground.
  • Page 25 (voltage or current). The large value of C should be increased immediately before LTC4000 parameters that vary with temperature include larger values of C are tried. This will normally bring about the transconductance and the output resistance of the the over damped starting condition for further iteration.
  • Page 26 24.9kΩ such that the voltage at the CL pin is 1.25V. Similar to the IIMON pin, the regulation voltage In this design example, the LTC4000 is paired with the on the IBMON pin is clamped at 1V with an accurate LT3845A buck converter to create a 10A, 3-cell LiFePO internal reference.
  • Page 27 LTC4000 applicaTions inForMaTion • The charge termination time is set at 2.9 hours accord- • The range of valid temperature for charging is set at ing to the following formula: –1.5°C to 41.5°C by picking a 10k Vishay Curve 2 NTC...
  • Page 28 LTC4000 applicaTions inForMaTion With C = 1µF, R = 10k at V = 20V, V = 7V, V The transient response now indicates an overall under regulated at 9.8V and a 0.2A output load condition at damped system. As noted in the empirical loop compensa-...
  • Page 29 BIAS based on the results obtained for all the loops. In this as close to the LTC4000 as possible. This allows as short particular example, the value of C is finally set to 47nF a route as possible from C...
  • Page 30 LTC4000 applicaTions inForMaTion APPENDIX—THE LOOP TRANSFER FUNCTIONS The Input Current Regulation Loop When a series resistor (R ) and capacitor (C ) is used The feedback signal for the input current regulation loop as the compensation network as shown in Figure 11, the...
  • Page 31 LTC4000 applicaTions inForMaTion The Output Voltage Regulation Loop The Battery Float Voltage Regulation Loop The feedback signal for the output voltage regulation loop The battery float voltage regulation loop is very similar to is the voltage on the OFB pin, which is connected to the the output float voltage regulation loop.
  • Page 32 LTC4000 applicaTions inForMaTion In Figure 22 the battery is approximated to be a signal The Battery Charge Current Regulation Loop when ground in series with the internal battery resistance R > V OUT(INST_ON) Therefore, the simplified loop transmission is as follows: In this operating region, the external charging PFET’s gate...
  • Page 33   •  •  sidered a small signal ground. However, in the LTC4000 s + 1   fIDC fIDC the external PFET regulation is purposely made slow to ...
  • Page 34 LTC4000 Typical applicaTions 15V TO 60V 2.2µF BSC123NO8NS3 10A MAX WÜRTH ELEKTRONIC 47µF 74435561100 10µH Si7135DP 12V, 15A 33µF B160 ×3 BSC123NO8NS3 1.5nF 0.1µF SYNC BOOST BAS521 SGND 1.15M 1µF 1N4148 LT3845A 182k 49.9k 16.2k BURST_EN SENSE – SENSE BIAS...
  • Page 35 LTC4000 Typical applicaTions PA1494.362NL 3.3µH 3.3mΩ 2.5mΩ 6V TO 18V 10Ω 15A MAX 150µF 22µF ×4 INTV 10Ω BAS140W 22V, 5A – SENSE SENSE 22µF INTV BOOST ×5 0.1µF PLLINMODE 150µF INTV 100k BSC027N04 1.87M PGOOD 4.7µF LTC3786 BIAS 232k 0.1µF...
  • Page 36 LTC4000 Typical applicaTions 4000fb For more information www.linear.com/LTC4000...
  • Page 37 LTC4000 package DescripTion Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. UFD Package 28-Lead Plastic QFN (4mm × 5mm) (Reference LTC DWG # 05-08-1712 Rev B) 0.70 ±0.05 4.50 ±0.05 3.10 ±0.05 2.50 REF 2.65 ±0.05 3.65 ±0.05 PACKAGE OUTLINE 0.25 ±0.05...
  • Page 38 LTC4000 package DescripTion Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. GN Package 28-Lead Plastic SSOP (Narrow .150 Inch) (Reference LTC DWG # 05-08-1641 Rev B) .386 – .393* .045 ±.005 .033 (9.804 – 9.982) (0.838) 19 18 17 1615 .254 MIN...
  • Page 39 36, 40 4000fb Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- For more information www.linear.com/LTC4000 tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
  • Page 40 Thermally Enhanced 4mm × 4mm QFN and 20-Pin TSSOP 4000fb Linear Technology Corporation LT 0613 REV B • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/LTC4000 (408) 432-1900 FAX: (408) 434-0507 www.linear.com/LTC4000  LINEAR TECHNOLOGY CORPORATION 2011 ● ●...