Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - battery management Charge management Li-Ion, Li-Po MSOP 8 EP Surface-mount

LTC4070

4070fc

Typical applicaTion

DescripTion

Li-Ion/Polymer Shunt

Battery Charger System

The LTC

4070 allows simple charging of Li-Ion/Polymer

batteries from very low current, intermittent or continuous

charging sources. The 450nA to 50mA operating cur-

rent makes charging possible from previously unusable

sources. With the addition of an external pass device,

shunt current may be boosted to 500mA. Stacked cell high

voltage battery packs are inherently balanced with shunt

charging. With its low operating current, the LTC4070 is

well suited to charge thin film batteries in energy harvesting

applications where charging sources may be intermittent

or very low power. The unique architecture of the LTC4070

allows for an extremely simple battery charger solution;

requiring just one external resistor.

The LTC4070 offers a pin selectable float voltage with 1%

accuracy across the full range of operating temperature

and shunt current. The integrated thermal battery quali-

fier extends battery lifetime and improves reliability by

automatically reducing the battery float voltage at NTC

thermistor temperatures above 40°C. The LTC4070 also

provides both low and high battery status outputs. For

applications requiring pack protection, see LTC4071.

The device is offered in two thermally enhanced packages,

a compact low profile (0.75mm) 8-lead (2mm × 3mm)

DFN and an 8-lead MSOP package.

FeaTures

applicaTions

Low Operating Current (450nA)

1% Float Voltage Accuracy Over Full Temperature

and Shunt Current Range

50mA Maximum Internal Shunt Current

(500mA with External PFET)

Pin Selectable Float Voltage Options:

4.0V, 4.1V, 4.2V

Ultralow Power Pulsed NTC Float Conditioning for

Li-Ion/Polymer Protection

Suitable for Intermittent, Continuous and Very Low

Power Charging Sources

Low and High Battery Status Outputs

Simple Low Voltage Load Disconnect Application

Thermally Enhanced, Low Profile (0.75mm)

8-Lead (2mm × 3mm) DFN and MSOP Packages

Low Power Li-Ion/Polymer Battery Back-Up

Solar Power Systems with Back-Up

Memory Back-Up

Embedded Automotive

Thin Film Batteries

Energy Scavenging/Harvesting

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and

ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property

of their respective owners..

NTC Overtemperature Battery Float

Voltage Qualifying

Simple Shunt Charger with Load Disconnect

and NTC Conditioning

TEMPERATURE (°C)

(V)

4.3

4.2

4.0

4.1

3.9

3.8

3.7

4020

4070 TA01b

80 100

ADJ = V

ADJ = FLOAT

ADJ = GND

4070 TA01a

LTC4070

ADJ

GND

10k

Li-Ion

NTCBIAS

LBO

NTC

NTHS0805N02N1002F

Q1:FDR8508

Summary of content (16 pages)

PAGE 1
LTC4070 Li-Ion/Polymer Shunt Battery Charger System Features n n n n n n n n n Low Operating Current (450nA) 1% Float Voltage Accuracy Over Full Temperature and Shunt Current Range 50mA Maximum Internal Shunt Current (500mA with External PFET) Pin Selectable Float Voltage Options: 4.0V, 4.1V, 4.
PAGE 2
LTC4070 Absolute Maximum Ratings (Notes 1, 2) ICC........................................................................ ±60mA ADJ, NTC, NTCBIAS, DRV, LBO, HBO Voltages............................................–0.3V to VCC + 0.3V Operating Junction Temperature Range... –40°C to 125°C Maximum Junction Temperature .......................... 125°C Storage Temperature Range................... –65°C to 150°C Peak Reflow Temperature......................................
PAGE 3
LTC4070 Electrical Characteristics The l denotes the specifications which apply over the full operating junction temperature range. VNTC = VCC, TA = 25°C unless otherwise specified. Current into a pin is positive and current out of a pin is negative. All voltages are referenced to GND unless otherwise noted.
PAGE 4
LTC4070 Typical Performance Characteristics Battery Discharge ICC vs VCC ADJ = GND 900 9 4.25 8 700 7 600 500 400 FALLING 300 5 4 1 2 3 0 4 VCC (V) 90 800 80 700 70 600 60 VHBTH (mV) 900 ICCQ (nA) 100 500 400 200 20 100 10 100 20 30 40 ICC (mA) 50 3.90 –50 250 200 100 50 –25 0 25 50 75 TEMPERATURE (°C) 100 0 –50 125 –25 ADJ = VCC 300 ADJ = FLOAT 280 3.230 3.225 3.220 3.210 260 ADJ = GND 240 ADJ = GND 3.215 3.
PAGE 5
LTC4070 Typical Performance Characteristics VOH LBO/HBO vs ISOURCE VOL LBO/HBO vs ISINK 2.5 2.5 1.5 HBO VCC = VF – 25m 1.0 0.5 0 0 0.5 2.0 1.0 1.5 ISOURCE (mA) PSD (µVRMS/√Hz) 2.5 1.0 0 3.0 0 2 4070 G10 Hot Plug Transient, CC = 330µF, RIN = 81Ω CC = 10µF, ICC = 1mA, 1Hz Res Bandwidth, Noise = 1.0452mVRMS from 10Hz to 100kHz 30 1.5 0.5 Power Spectral Density 35 VCC = 3.7V 2.0 LBO VCC = 3.1V VOL (V) VCC – VOH (V) 2.0 TA = 25°C, unless otherwise noted.
PAGE 6
LTC4070 Pin Functions HBO (Pin 4): High Battery Monitor Output (Active High). HBO is a CMOS output that indicates that the battery is almost fully charged and current is being shunted away from BAT. This pin is driven high when VCC rises to within VHBTH of the effective float voltage. The absolute value of this threshold depends on ADJ and NTC, both of which affect the float voltage. HBO is driven low when VCC falls by more than (VHBTH + VHBHY) below the float voltage.
PAGE 7
LTC4070 Operation The LTC4070 provides a simple, reliable, and high performance battery protection and charging solution by preventing the battery voltage from exceeding a programmed level. Its shunt architecture requires just one resistor between the input supply and the battery to handle a wide range of battery applications. When the input supply is removed and the battery voltage is below the high battery output threshold, the LTC4070 consumes just 450nA from the battery.
PAGE 8
LTC4070 Operation For example, if the NTC thermistor requires the float voltage to be dropped by 100mV (ADJ = VCC and 0.29•VNTCBIAS < VNTC < 0.36•VNTCBIAS) then the HBO rising threshold is detected when VCC rises past VFLOAT – DVFLOAT(NTC) – VHBTH = 4.2V – 100mV – 40mV = 4.06V. The HBO falling threshold in this case is detected when VCC falls below VFLOAT – DVFLOAT(NTC) – VHBTH – VHBHY = 4.2V – 100mV – 40mV – 100mV = 3.96V. Low Battery Status Output: LBO When the battery voltage drops below 3.
PAGE 9
LTC4070 Applications Information 24V WALL ADAPTER RIN 110Ω 4W NTC FLOAT IF NOT NEEDED LTC4070 NTCBIAS VCC DRV Q1 ADJ + Li-Ion GND BATTERY Q1: FDN352AP 4070 F02 Figure 2. Single-Cell Charger with Boosted Drive WALL ADAPTER RIN VCC1 NTC VCC The LTC4070 can also be used to regulate series-connected battery stacks as illustrated in Figures 3 and 4. Here two LTC4070 devices are used to charge two batteries in series; with or without boosted drive.
PAGE 10
LTC4070 Applications Information The voltage at the NTC pin depends on the ratio of the NTC thermistor value, RNTC, and a bias resistor, RNOM. Choose RNOM equal to the value of the thermistor at 25°C. RNOM is 10k for a Vishay NTHS0402N02N1002F thermistor with a B25/85 value of 3490. RNOM must be connected from NTCBIAS to NTC.
PAGE 11
LTC4070 typical Applications DANGER! HIGH VOLTAGE! AC 110 R3 249k R1 249k R4 249k R2 249k MB4S – + VCC NTC FLOAT IF NOT NEEDED ADJ LTC4070 NTCBIAS + Li-Ion GND BATTERY 4070 F05 DANGEROUS AND LETHAL POTENTIALS ARE PRESENT IN AC LINE-CONNECTED CIRCUITS! BEFORE PROCEEDING ANY FURTHER, THE READER IS WARNED THAT CAUTION MUST BE USED IN THE CONSTRUCTION, TESTING AND USE OF AC LINE-CONNECTED CIRCUITS. EXTREME CAUTION MUST BE USED IN WORKING WITH AND MAKING CONNECTIONS TO THESE CIRCUITS.
PAGE 12
LTC4070 typical Applications The LTC4070 status pins have sufficient drive strength to use with an LED, for a visual indication of charging status. Consider the application in Figure 7, where red LED D1 is connected to the LBO pin and turns off when the battery voltage is below VLBTH . Note that LED D1 discharges the battery until VCC falls below VLBTH . Green LED D2, connected to the HBO pin turns on while the battery is charging.
PAGE 13
LTC4070 Package Description DDB Package 8-Lead Plastic DFN (3mm ¥ 2mm) (Reference LTC DWG # 05-08-1702 Rev B) 0.61 ±0.05 (2 SIDES) 3.00 ±0.10 (2 SIDES) 0.70 ±0.05 2.55 ±0.05 1.15 ±0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.20 ±0.05 (2 SIDES) PIN 1 BAR TOP MARK (SEE NOTE 6) 0.200 REF RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS R = 0.115 TYP 5 R = 0.05 TYP 0.40 ± 0.10 8 2.00 ±0.10 (2 SIDES) 0.56 ± 0.05 (2 SIDES) 0.75 ±0.05 0 – 0.05 4 0.25 ± 0.05 1 PIN 1 R = 0.20 OR 0.
PAGE 14
LTC4070 MS8E Package Package Description 8-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1662 MS8E Package Rev E) 8-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1662 Rev E) BOTTOM VIEW OF EXPOSED PAD OPTION 2.06 ± 0.102 (.081 ± .004) 1 0.889 ± 0.127 (.035 ± .005) 2.794 ± 0.102 (.110 ± .004) 0.29 REF 1.83 ± 0.102 (.072 ± .004) 0.05 REF 5.23 (.206) MIN DETAIL “B” CORNER TAIL IS PART OF DETAIL “B” THE LEADFRAME FEATURE. FOR REFERENCE ONLY NO MEASUREMENT PURPOSE 2.
PAGE 15
LTC4070 Revision History REV DATE DESCRIPTION PAGE NUMBER A 4/10 Change Q1’s Part Number on Figure 6 12 B 9/10 Updated Description section 1 Temperature Range updated in Order Information section 2 Updated Note 2 3 Text updated in “NTC Qualified Float Voltage, ∆VFLOAT(NTC)” section 7 Text updated in “NTC Protection” section Updated Related Parts section C 4/11 Updated Vishay thermistor part number.
PAGE 16
LTC4070 Typical Application 12V RIN 41.2Ω 2W Q2: FDR8508 LTC4070 FLOAT SYSTEM STATUS D1 LTST C190KGKT VCC ADJ HBO RLED 2.67k LBO DRV NTCBIAS NTC GND Q1: FDN352AP RNOM 10k T RNTC: NTHS0402N02N1002F 10k + Li-Ion 4070 TA02 Figure 9. 12V Wall Adapter Charging with 205mA with Automatic Load Disconnect on Low Battery Related Parts PART NUMBER DESCRIPTION COMMENTS Shunt Regulators LT1389 Nanopower Precision Shunt Voltage Reference 800nA Operating Current, 0.