MC34280 Datasheet, PDF (2/20 Pages) ON Semiconductor – Power Supply & Management IC for Handheld Electronic Products

MC34280
Figure 1. Typical Application Block Diagram
CVDD
c = 20u
Battery
Lock
Switch
VBAT
GND
Riref
Cpor
Ren
r = 480 k
GND
VREF ^{c = 80n GND r = 1000 k}
GND
GND
CMAINb
c = 100p
RMAINb
r = 1000 k
IREF AGND VREF
PDELAY VDD ENABLE VBAT VMAINFB
8
7 6 5 VDD 4
3
2
1
VBAT
Optional
CMAINbp
c = 100u
10 V SMT
tantalum
GND
VBAT
R123
LMAIN
r=5
L = 33u
(Rs < 60 mOhm)
RLBa
r = 300 k
RLBb
r = 900 k
LOWBATSEN
DGND ⁹
10
GND GND
PORB
11
LOWBATB
LIBATON ¹²
LIBATCL ¹³
14
Power
ON
Reset
Voltage
Reference
Lithium
Battery
Backup
Current
Bias
Low
Battery
Detect
Control and
Gate Drive
Startup
d
sd
M2
Current
Limit
M1
s
Main Regulator with
Synchronous Rectifier
d
VMAIN
VMAIN
32
1N5817
31 _VMAINSW
VMAINGND
30
29 N/C ^GND
28 ^LIBATOUT
CMAIN
c = 100u
10 V SMT
tantalum
GND
M3
s
LIBATIN
27
PORB
LOWBAT
LIBATON
LIBATCL
VAUXADJ
VAUXCON
VAUXEN
VAUXADJ
15
VAUXCON
Level
Control
Current
Limit
Control and
Base Drive
Q1
16
Auxiliary Regulator
VAUXEMR
26
VAUXSW
25
GND
GND
17 18
VAUXEN
VAUXFBP
19
20
VAUXFBN VBAT
VAUXREF
(1.1 V to 2.2 V)
21
VAUXBDV
22 23 24
N/C
VAUXBASE
VAUXCHG
VBAT
Optional
LAUX
L = 22u
(Rs < 60 mOhm)
CAUXbp
c = 100u
10 V SMT
tantalum
GND
1N5818
VAUX
30 V SMT
tantalum
Caux
c = 30u
GND
Rauxb
r = 2.2 M
Rauxa
r = 200 k
Optional
CAUXb
c = 2n
CAUXa
c = 33n
GND
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