Suffix M indicates that the part is available in Surface
Mount package. Suffix X indicates that the part is available in
2.5k units on Tape and Reel.
* Current is sampled over a fixed interval. The average
current during this interval is indicated by the duty cycle of
the PWM output during next interval.
The Package code M08A is internal to National Semicon-
ductor and indicates an 8-lead surface mount package,
SO-8.
Pin Description (High-Side, LM3814)
Pin Description (High-Side, LM3814)
Pin
1
2
3
4
5
6
7
8
SENSE−
FLTR+
FLTR−
SD
PWM
GND
GND
Name
SENSE+, V
DD
Low side of internal current sense.
Filter input — provides anti-aliasing for delta sigma modulator.
Filter input.
Shutdown pin. Connected to V
DD
through a pull up resistor for normal operation. When
low, the IC goes into a low current mode (typically 3 µA).
PWM output indicates the current magnitude and direction.
Ground
Ground
Function
High side of internal current sense, also supply voltage.
Pin Description (Low-Side, LM3815)
Pin Description (Low-Side, LM3815)
Pin
1
2
3
4
5
6
7
8
SENSE−
FLTR+
FLTR−
SD
PWM
GND
V
DD
Name
SENSE+, GND
Low side of internal current sense.
Filter input – provides anti-aliasing for delta sigma modulator.
Filter input.
Shutdown pin. Connected to V
DD
through a pull up resistor for normal operation. When
low, the IC goes into a low current mode (typically 3 µA).
PWM output indicates the current magnitude and direction.
Ground
V
DD
(supply)
Function
High side of internal current sense, also ground.
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2
LM3814/LM3815
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Absolute Maximum Supply Voltage
Power Dissipation
ESD Susceptibility (Note 3)
Sense Current (peak, for 200 msec) (Note 4)
Sink Current for PWM pin
Voltage on Pin 5
5.5V
(Note 2)
1.5 kV
10A
1 mA
5.25V
Maximum Junction Temperature
Storage Temperature
Lead Temperature (Soldering, 10 sec)
150˚C
−65˚C to +150˚C
260˚C
Operating Ratings
(Note 1)
Input Voltage
Sense Current (continuous) (Note 4)
Junction Temperature Range
2.0V to 5.25V
7A
−40˚C to +125˚C
Electrical Characteristics
LM3814-1.0, LM3815-1.0
V
DD
= 5.0V for the following specifications. Supply bypass capacitor is 1µF and filter capacitor is 0.1µF.
Symbol
I
ACC
Parameter
Average Current Accuracy
(Note 7)
Effective Output Noise (rms)
Conditions
at 0.9A current
Typ
(Note 5)
0.9
0.868 /
0.850
0.932 /
0.950
e
n
12
Limit
(Note 6)
Units
A
A (min)
A (max)
mA
LM3814-7.0, LM3815-7.0
V
DD
= 5.0V for the following specifications. Supply bypass capacitor is 1µF and filter capacitor is 0.1µF.
Symbol
I
ACC
Parameter
Average Current Accuracy
(Note 7)
Effective Output Noise (rms)
Conditions
at 2.5A current (Note 8)
Typ
(Note 5)
2.5
2.350 /
2.288
2.650 /
2.712
e
n
120
Limit
(Note 6)
Units
A
A (min)
A (max)
mA
Common Device Parameters
Unless otherwise specified, V
DD
= 5.0V for the following specifications. Supply bypass capacitor is 1µF and filter capacitor is
0.1µF.
Symbol
I
Q1
I
Q2
D
RES
t
S
Parameter
Quiescent Current
Quiescent Current
PWM Resolution
Sampling Time
Conditions
Normal Mode, SD = high
Shutdown Mode, SD = low
Typ
(Note 5)
100
160
2.5
10
0.8
6
4
10
f
P
Frequency of PWM Waveform
160
100
250
V
TH
V
TL
V
OH
Threshold High Level for SD
Threshold Low Level for SD
Logic High Level for PWM
Load current = 1mA, 2V
≤
V
DD
≤
5.25V
3
Limit
(Note 6)
Units
µA
µA (max)
µA
µA (max)
%
ms
ms (min)
ms (max)
Hz
Hz (min)
Hz (max)
V
V (min)
V
V (max)
V
V (min)
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1.2
1.8
1.3
0.7
V
DD
− 0.05
V
DD
− 0.2
LM3814/LM3815
Electrical Characteristics
Unless otherwise specified, V
DD
0.1µF.
Symbol
V
OL
P
I
Parameter
Logic Low Level for PWM
Insertion Loss
(Continued)
Common Device Parameters
(Continued)
= 5.0V for the following specifications. Supply bypass capacitor is 1µF and filter capacitor is
Typ
(Note 5)
0.04
0.2
0.004
Limit
(Note 6)
Conditions
Sink current = 1mA, 2V
≤
V
DD
≤
5.25V
I
SENSE
= 1A (Note 9)
Units
V
V (max)
Ω
Note 1:
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see Electrical Characteristics. The
guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed
test conditions.
Note 2:
At elevated temperatures, devices must be derated based on package thermal resistance. The device in the surface-mount package must be derated at
θ
JA
= 150˚C/W (typically), junction-to-ambient.
Note 3:
The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin.
Note 4:
The absolute maximum peak and continuous currents specified are not tested. These specifications are dependent on the
θ
JA
, which is 150˚C/W for the
S08 package.
Note 5:
Typical numbers are at 25˚C and represent the most likely parametric norm. Specifications in standard type face are for T
J
= 25˚C and those with
boldface
type
apply over
full operating temperature ranges.
Note 6:
Limits are 100% production tested at 25˚C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control
(SQC) methods. The limits are used to calculate National’s Averaging Outgoing Quality Level (AOQL).
Note 7:
There is a variation in accuracy over time due to thermal effects. Please refer to the PWM Output and Current Accuracy section for more information.
Note 8:
The PWM accuracy for LM3814-7.0 and LM3815-7.0 depends on the amount of copper area under pins 1 and 2, and the layout. Please refer to the "PWM
Output and Current Accuracy" section for more information.
Note 9:
The tolerance of the internal lead frame resistor is corrected internally. The temperature coefficient of this resistor is 2600 ppm/˚C.
Typical Performance Characteristics
Supply bypass capacitor is 0.1µF and filter capacitor is
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