MIC5156 Micrel Semiconductor, MIC5156 Datasheet - Page 11

• Manufacturer Part Number: MIC5156
• Description: Super LDO Regulator Controller
• Manufacturer: Micrel Semiconductor

MIC5156/5157/5158
Uninterruptible Power Supply
The MIC5157 and two N-channel MOSFETs provide battery
switching for uninterruptible power as shown in figure (6).
Two MOSFETs are placed source-to-source to prevent cur-
rent flow through their body diodes when switched off. The
Super LDO regulator is continuously enabled to achieve fast
battery switch-in. Careful attention must be paid to the ac-line
monitoring circuitry to ensure that the output voltage does not
fall below design limits while the battery is being switched in.
Line
Battery
AC
Figure 6. UPS Power Supply Concept
Line
Figure 5. Battery Charger Concept
EN
Power Supply
EN
MIC5158
Off-line
GND
MIC5158
V
GND
DD
1N4148
V
EA
DD
G
D
S
EA
G
D
S
Q1
Q2
R1
R2
G
G
D
S
S
D
V
40V max.
MOSFET body diodes
shown for clarity
IN
R3
Uninterruptable
DC
R4
3-122
March 1999
Micrel