Datasheet TK65010TL Datasheet (TOKO)

TK65010

01S

ADVANCED

INFORMATION

FEATURES

■ Very Low Quiescent Current ( 5 µA)

■ Dual Comparator Outputs

■ Single Monitor Input

■ Miniature Package (SOT-23-5)

DESCRIPTION

The TK65010 battery voltage monitor is designed for
portable battery powered systems where board space and
cost are important design considerations. The proprietary
monitoring architecture of the TK65010 allows two separate
warning thresholds to be set utilizing a single resistor
divider and single input pin.

The first warning indicator, a Low Battery Output (LBO), is
intended to warn the battery powered system of a low
battery condition. In such a condition, the LBO may be
used to alert the system to illuminate a low battery indicator
and to take appropriate action preparing for battery failure.

BATTERY VOLTAGE MONITOR

APPLICATIONS

■ Battery Powered Systems

■ Cellular Telephones

■ Pagers

■ Personal Communications Equipment

TK65010

V

IN

GND

V

MON

LBO

DBO

The second warning indicator, a Dead Battery Output
(DBO), is intended to be used by the system for shutdown
purposes. The availability of the DBO allows the system to
shut down in order to minimize deep discharge of the
battery.

BLOCK DIAGRAM

The two warning indicators can be implemented utilizing
the TK65010 and only two external components.

V

The TK65010 is available in a miniature 5-pin SOT-23-5

CC

710 mV

LBO

surface mount package.

ORDERING INFORMATION

V

MON

700 mV

TK65010

Tape/Reel Code

TAPE/REEL CODE

TL: Tape Left

GND

690 mV

January 1999 TOKO, Inc. Page 1

DBO

TK65010

ABSOLUTE MAXIMUM RATINGS

All Pins Except GND .................................................. 6 V

Power Dissipation (Note 1) .......................................TBD

Storage Temperature Range ................... -55 to +150 °C

TK65010 ELECTRICAL CHARACTERISTICS

VIN = 5 V, TA = Tj = Full Operating Temperature Range, unless otherwise specified.

LOBMYSRETEMARAPSNOITIDNOCTSETNIMPYTXAMSTINU

Operating Temperature Range ...................-20 to +80 °C

Junction Temperature ...........................................150 °C

V

NI

V

OBL,HT

V

AO,fer

V

OBD,HT

V
V

I

BF

I

Q

V

OBL

V

OBD

Note 1: Power dissipation is 400 mW when mounted as recommended (200 mW In Free Air). Derate at 1.6 mW/°C for operation above 25 °C.
Note 2: When using test circuit below.

TSYH,OBL,HT

TSYH,OBD,HT

egnaRylppuStupnI9.06V

dlohserhTrotarapmoCOBL 017Vm

ecnerefeRpmA-PO 007Vm

dlohserhTrotarapmoCOBD 096Vm

siseretsyHrotarapmoCOBL DBTVm

siseretsyHrotarapmoCOBD DBTVm

tnerruCkcabdeeFkaePV

V=

NOM

OBL,HT

085-An

tnerruCtnecseiuQ 5Aµ

dlohserhTyrettaBwoL)2etoN(1.1V

dlohserhTyrettaBdaeD)2etoN(9.0V

TEST CIRCUIT

V

GND

V

IN

MON

BATTERY IN

R

301 K

R

1 M

1

2

Page 2 January 1999 TOKO, Inc.

LBO

LOW BATTERY

DBO

DEAD BATTERY

THEORY OF OPERATION

TK65010

The circuit in Figure 1 illustrates a typical application
utilizing the TK65010. The TK65010 differs from most
voltage monitors due to the fact that two separate
comparator thresholds can be set utilizing a single resistive
divider and a single input pin. One comparator output is
used as an early “low battery” warning. The second
comparator can be used as a later “dead battery” warning.

BATTERY IN

R

301 K

R
1 M

IN

1

2

GND

V

MON

I

FB

LBO

DBO

LOW BATTERY

DEAD BATTERY

V

FIGURE 1

In a typical voltage monitor, which uses an external resistive
divider for setting the voltage monitor threshold, the input
bias current to the monitor pin is essentially zero. In this
type of scenario, the voltage on the monitor input would be
a resistively divided version of the battery voltage. The
TK65010 introduces a small feedback current (IFB) which
introduces a “plateau” into the transfer characteristics
between the battery voltage and the voltage monitoring
pin. The width of this plateau is dependent upon the current
range of the feedback current (IFB) and the values of the
external resistor network. Figure 2 illustrates the typical
relationship between the battery voltage (VIN), the feedback
current (IFB) and the voltage on the monitoring pin (V

MON

Under these conditions, current will be flowing into the
V

pin and will be limited to approximately 580 nA. As

MON

the battery voltage drops, the voltage on the V
drop proportionately. When the voltage on the V
passes through approximately 710 mV, the output of the
first comparator (LBO) will transition from a high to a low
state. Shortly after the LBO output has been asserted, as
the input voltage continues to drop, the magnitude of the
current into the V

pin will begin to proportionately

MON

decrease as the input voltage decreases. An op-amp
feedback loop internal to the TK65010 will attempt to
maintain the voltage on the V

pin at a constant value of

MON

approximately 700 mV (thus, the plateau). As the battery
voltage continues to drop, there comes a point where the
feedback current decreases to approximately zero. A this
point, the voltage on the V

pin will resume a proportional

MON

drop with the input voltage. As the voltage on the V
passes through approximately 690 mV, the second
comparator output (DBO) will be asserted.

For details on how to properly select the resistor divider,
refer to the “Design Considerations” section.

V

LBO

V

IN

V

MON

).

580 nA

700 mV

V

DBO

MON

pin will

pin

MON

pin

MON

In selecting a resistor divider network, there are typically
two degrees of freedom when selecting values. The first

I

FB

0 nA

criteria in selecting the divider is the ratio of the two
resistors. Selecting the ratio defines the lower threshold of
the voltage monitor (DBO). The second degree of freedom
when selecting the resistor divider is the absolute resistance

LBO

values. This second degree of freedom can be utilized to
set a secondary monitoring threshold (LBO) greater than
the first.

DBO

Typically, when the battery voltage is relatively high, the
voltage on the V
divided version of the battery voltage minus the offset. The

pin of the TK65010 will be a resistively

MON

FIGURE 2

magnitude of the offset voltage will be dependent upon the
resistor values comprising the external divider and the
magnitude of the feedback current flowing into the IFB pin.

January 1999 TOKO, Inc. Page 3

TK65010

PIN DESCRIPTION

SUPPLY VOLTAGE PIN (VIN)

This pin is the positive power supply for the TK65010.
Current draw from the positive supply is typically 5 µA.

GNOUND PIN (GND)

The pin provides the ground connection for the IC.

VOLTAGE MONITORING PIN (V

This pin is the voltage monitoring pin of the TK65010.
When the voltage on this pin is less than approximately
710 mV, the LBO signal will be asserted. When the voltage
on this pin is less than approximately 690 mV, the DBO pin
will be asserted. This pin is also connected to the negative
input of a high-gain op-amp. The op-amp will attempt to
maintain the voltage on this pin at 700 mV. However, the
current-sink capability of this pin is limited to the range of
0 to 580 nA.

LOW BATTERY OUTPUT PIN (LBO)

This active-low pin will be asserted when the voltage on the
V

pin is less than approximately 710 mV; otherwise the

MON

LBO pin will not be asserted.

DEAD BATTERY OUTPUT PIN (DBO)

This active-low output will be asserted when the voltage in
the V
the DBO pin will not be asserted.

pin is less than approximately 690 mV; otherwise

MON

MON

)

Page 4 January 1999 TOKO, Inc.

DESIGN CONSIDERATIONS

TK65010

In order to design a voltage monitor utilizing the TK65010,
the two external resistors comprising the resistor divider
must be properly selected. Selecting the ratio of the
resistors will establish the lower monitoring threshold
(DBO). Selecting the value of the R1 will establish the
upper monitoring threshold (LBO) relative to the lower
(DBO) threshold. The value of R2 will be dictated by the
ratio R1/R2 and the value of R1. For the following
explanations, please refer to the circuit diagram of
Figure 3.

SETTING THE DBO THRESHOLD

As mentioned above, the ratio of R1/R2 established the
”dead battery” threshold. The dead battery comparator
trips when the voltage on the V
approximately 690 mV and the current into the V

pin passes through

MON

MON

pin is
approximately zero. Given the required dead battery
threshold, the ratio R1/R2 can be selected utilizing the
following equation:

DBO Threshold = 690 mV x (1 + R1/R2)

or

R1/R2 = (DBO Threshold - 690 mV) / 690 mV

RESISTOR TOLERANCE CONSIDERATIONS

The tolerance of the LBO and DBO thresholds will have a
significant dependence upon the tolerance of the resistive
components used in the resistor divider. When utilizing the
previously described equations for setting the LBO and
DBO thresholds, it is possible that optimal values of the
resistive elements R1 and R2 may be relatively large. Since
large resistive components are not always available with
tight tolerances, an alternate method can be used for
applications where tighter tolerances are required.

The purpose of the resistor divider connected between the
Battery Input and the V

pin is twofold. The first purpose

MON

is to appropriately select the divider ratio such that the
DBO threshold is set to the desired level. The second
purpose is to select the absolute resistor values such that
the LBO threshold is set to an appropriate level relative to
the DBO threshold. Effectively, an attenuated voltage
source with a relatively large output impedance is driving
the V

pin. This scenario is illustrated in Figure 4.

MON

V

IN

R

1

V

MON

SETTING THE LBO THRESHOLD

R

2

The threshold of the LBO comparator will be at a value
greater than the DBO threshold. The value of resistor
value R1 dictates the difference between the LBO and
DBO thresholds as follows:

LBO Threshold = DBO Threshold x 1.029 + R1 x 580 nA
or

R1 = (LBO Threshold - DBO Threshold x 1.029) / 580 nA

V

BATTERY IN

IN

R

1

R

2

GND

V

MON

I

FB

LBO

DBO

LOW BATTERY

DEAD BATTERY

V

IN

R1 + R

x R

2

2

R1 x R
R1 + R

+

FIGURE 4

2
2

V

MON

FIGURE 3

January 1999 TOKO, Inc. Page 5

TK65010

DESIGN CONSIDERATIONS (CONT.)

The resistor divider consisting of R1/R2 can be scaled
downward by a factor scale factor (K) to utilize smaller
resistor values K x R1 and K x R2 (K < 1). By adding an
additional series resistor, which can be dependent upon
the scale factor (K) and the resistor values comprising the
divider, the V
source and drive impedance as illustrated in Figure 4. The
three-resistor attenuator is illustrated below in Figure 5.

pin will effectively see the same voltage

MON

V

IN

V

IN

R1 + R

K x R

x R

2

K x R

1

2

2

FIGURE 5

+

R1 x R

R1 + R

(1- K) x

2
2

R1 x R

R1 + R

V

2

2

MON

V

MON

Page 6 January 1999 TOKO, Inc.

Li-ion
CELL

APPLICATIONS INFORMATION

V

IN

V

GND

MON

R

715 K

R

215 K

1

2

FIGURE 6: BASIC BATTERY MONITOR

LBO

DBO

TK65010

LOW BATTERY

DEAD BATTERY

Low Battery Threshold = 3.5 V
Dead Battery Threshold = 3.0 V

BATTERY
VOLTAGE

BATTERY
VOLTAGE

R

1

1.23 M

R

2

90.9 K

+5 V

V

V

IN

GND

MON

LBO

DBO

FIGURE 7: HIGH VOLTAGE MONITOR

R

1 M

R

2

73.2 K

+5 V

1

13 K

GND

V

V

IN

MON

LBO

DBO

LOW BATTERY

DEAD BATTERY

Low Battery Threshold = 11.0 V
Dead Battery Threshold = 10.0 V

LOW BATTERY

DEAD BATTERY

Low Battery Threshold = 11.1 V
Dead Battery Threshold = 10.1 V

FIGURE 8: HIGH VOLTAGE MONITOR WITH 3-RESISTOR ATTENUATOR

January 1999 TOKO, Inc. Page 7

TK65010

)

PACKAGE OUTLINE

SOT-23-5

5

1

Marking Information

0.7

Marking

4

(0.6)

1.6

(0.6)

2

3

0.95

e

0.95

e

2.9

+0.15

- 0.05

0.4

1.3 max

+0.1

1.0

2.4

e1

e

e

0.95

0.95

1.90

e'

Recommended Mount Pad

0.1

M

1.1

(0.8)

Marking
TK65010 xxx

+0.15

0.1

Dimensions are shown in millimeters
Tolerance: x.x =

0.2 mm (unless otherwise specified

0 - 0.1

- 0.05

0.15

0.3

2.8
0 - 15 max

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The information furnished by TOKO, Inc. is believed to be accurate and reliable. However, TOKO reserves the right to make changes or improvements in the design, specification or manufacture of its
products without further notice. TOKO does not assume any liability arising from the application or use of any product or circuit described herein, nor for any infringements of patents or other rights of
third parties which may result from the use of its products. No license is granted by implication or otherwise under any patent or patent rights of TOKO, Inc.

Page 8 January 1999 TOKO, Inc.

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Printed in the USA© 1999 Toko, Inc.