LM3915N-1 National Semiconductor, LM3915N-1 Datasheet - Page 13

• Manufacturer Part Number: LM3915N-1
• Description: IC, DOT/BAR DISPLAY DRIVER, DIP-18
• Manufacturer: National Semiconductor

Specifications of LM3915N-1

• Led Driver Application: VU Meter, Power Meters
• No. Of Outputs: 10
• Output Current: 30mA
• Input Voltage: 3V To 25V
• Dimming Control Type: Analog
• Operating Temperature Range: 0°C To +70°C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Application Hints
the LED current will be at least 5 mA. R1 will typically be
between 1 kΩ and 2 kΩ. To trim the reference voltage, vary
R2.
The circuit in Figure 8 shows how to add a LED intensity
control which can vary LED current from 9 mA to 28 mA. The
reference adjustment has some effect on LED intensity but
the reverse is not true.
Multiple LM3915s
Figure 9 shows how to obtain a common reference trim and
intensity control for two LM3915s. The two ICs may be
connected in cascade for a 60 dB display or may be handling
(Continued)
FIGURE 7. Design Equations for Fixed LED Intensity
13
separate channels for stereo. This technique can be ex-
tended for larger numbers of LM3915s by varying the values
of R1, R2 and R3 in inverse proportion to the number of
devices tied in. The ICs’ internal references track within
100 mV so that worst case error from chip to chip is only
0.1 dB for V
REF
= 10V.
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