LM828M5/NOPB National Semiconductor, LM828M5/NOPB Datasheet - Page 8

• Manufacturer Part Number: LM828M5/NOPB
• Description: IC SW CAP/INV ADJ 25MA SOT23-5
• Manufacturer: National Semiconductor
• Type: Switched Capacitor (Charge Pump), Invertingr

Specifications of LM828M5/NOPB

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: -1.8 ~ -5.5 V
• Current - Output: 25mA
• Frequency - Switching: 12kHz
• Voltage - Input: 1.8 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-5, SC-74A, SOT-25
• Power - Output: 240mW
• Dc: 06+
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LM828M5/NOPBTR

www.national.com
COMBINED DOUBLER AND INVERTER
In Figure 5, the LM828 is used to provide a positive voltage
doubler and a negative voltage converter. Note that the total
current drawn from the two outputs should not exceed 40 mA.
REGULATING V
It is possible to regulate the negative output of the LM828 by
use of a low dropout regulator (such as the LP2980). The
whole converter is depicted in Figure 6. This converter can
give a regulated output from −1.8V to −5.5V by choosing the
proper resistor ratio:
OUT
V
out
where, V
= V
ref
ref
(1 + R
FIGURE 5. Increasing Output Voltage by Cascading Devices
= 1.23V
1
FIGURE 6. Combined Voltage Doubler and Inverter
/R
2
)
8
Note that the following conditions must be satisfied simulta-
neously for worst case design:
V
V
in_max
in_min
+ I
+ I
out_max
>V
< V
out_min
out_min
out_max
× R
× R
+V
out_max
out_min
+V
drop_max
drop_min
10013711
(LM828)
(LM828)
(LP2980)
10013710
(LP2980)