1
DESCRIPTION
Demonstration Circuit DC1584A is a Simple Low-Iq Battery Charger/Protector With NTC Thermistor featuring the
LTC®4070EDDB.
PERFORMANCE SUMMARY
Specifications are at T
A
= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VBUS
Input voltage R
LIMIT
= 169
Ω
10 12 16 V
V(BAT)
Battery Float Voltage ‘VFLOAT’ jumper on 4.1V, Constant Voltage
Mode. T
NTC
= 25°C
4.059 4.141 V
I(BAT)
Battery Charge Current Constant Current Mode, Vin = 12V, VCC =
3.8V
49.7 mA
QUICK START PROCEDURE
Refer to Figure 1 for the proper measurement
equipment setup and jumper settings and follow the
procedure below.
NOTE.
When measuring the input or output voltage ripple, care
must be taken to avoid a long ground lead on the oscilloscope
probe. Measure the input or output voltage ripple by touching the
probe tip directly across the VBUS or Vcc and GND terminals. See
Figure 2 for proper scope probe technique.
1. Set PS1 = 12V, PS2 = 3.6V, “VFLOAT” (JP2) to
4.1V. Observe I(VBUS) (AM1). The voltage on
the battery is below the LTC4070EDDB’s float
voltage. So all the current is flowing into the bat-
tery, and that current is (12V – 3.6V) /169(R1) =
49.7mA.
2. If “LBO” LED lit, decrease PS2 until off. Observe
BAT (VM2). The LBO output goes high when the
battery voltage is below 3.2V, but it has 200-
300mV of hysteresis. So it may not go low until
3.5V, with Vcc ↑.
3. Increase PS2 until LBO is lit. Observe BAT
(VM2).
4. Increase PS2 until HBO lit. Observe BAT (VM2).
The HBO LED will light when the battery voltage
is within ~50mV of the float voltage.
5. Disconnect PS2, AM2, and 3.6Ω resistor. Ob-
serve BAT (VM2). The only limit to the Vcc volt-
age now is the LTC4070, so the voltage will rise
to the float voltage.
6. Reset the Jumpers to their default position.
QUICK START GUIDE FO
R
DC1584
A
LTC4070EDDB: Simple Low-Iq
Battery Charger/Protecto
r
With NTC Thermistor Input
LTC4070EDDB
2
Figure 1. Proper Measurement Equipment Setup for DC1584A
VIN
GND
Figure 2. Measuring Input or Output Ripple
+
PS1 +
4.35V - 5.5V supply
1A -
-
+
VM1 + PS2
0V - 5V supply
- 1
A
3.6
Ω
-
+
VM2
-
AM2
+ -
AM1
Note: All connections from equipment should be Kelvin connected directly to the board
pins which they are connected on this diagram and any input or output leads should be
twisted pair.
LTC4070EDDB
3
Q1
FDN352AP
1
3 2
EXT
R2
200
C2
0.22uF
25V
0805
VFLOAT
C1
1uF
0603
25V
10 %
D1
LBO
12
Charging
OPT
VIN
OFF
Charged
D2
HBO
1 2
A
DC1584A
Wednes day , Nov ember 04, 2009
11
G. Barbehenn
G. Barbehenn
X
LTC4070EDDB: SIMPLE LOW - Iq BATTERY
CHARGER / PROTECTOR WITH NTC THERMISTOR INPUT
SIZE
DATE:
DWG NO. REV
SHEET OF
TITLE:
CONTRACT NO.
APPROVALS
DRAWN:
CHECKED:
APPROVED:
ENGINEER:
DESIGNER:
TECHNOLOGY
Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blv d.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER , IT REMAINS THE CU STOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
JP4
HBO LED
4.0V
R5
0
JP7
SHUNT
JP2
ON 25 mils clearance
R10
1.0
5 %
E6
HBO
E2
GND
R8
1K
5 %
LBO LED
ON OFF
Charged
U1
LTC4070EDDB
3
1
4
62
9
7
8
5
ADJ
NTCB IA S
HBO
LBONTC GND
DRV
VCC
GND
R4
0
E4
GND
R1
169
2512
1 %
JP1
OPT
R6
10k
R3
10k
JP6
JP3
OPT
ON
75mA
OPT
J1
DF3-3P-2DSA
1
2
3
BAT
GND
ENTC
25 mi ls clear ance
4.2V
OPT
E7
GND
25 mi ls clearance
R11
1.0
5 %
100uF
6.3V
1206
C3
20 %
E3
NTC
OFF
R9
1.0
5 %
E5
LBO
25 mi ls clear ance
JP5
Unless noted:
Resistors: Ohms, 0402, 1%, 1/16W
Capacitors: uF, 0402, 10%, 50V
OPT
NJC
PRODUCTION RELEASEA 10/15/09
REVISION HISTORY
DESCRIPTION DATEA PPROV EDECO REV
NTC
E8
BAT
Charging
E1
10V - 15V
VBUS
R7
1K
5 %
INT
4.1V
Figure 3. Schematic
LTC4070EDDB
4
Figure 4. Bill of Materials
