MC34704 FREESCALE [Freescale Semiconductor, Inc], MC34704 Datasheet - Page 26

• Manufacturer Part Number: MC34704
• Description: Multiple Channel DC-DC Power Management IC
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

OVERALL EFFICIENCY ANALYSIS
every single regulator directly from the battery to obtain full
output capability:
• MOSFET Conduction Losses
26
34704
FUNCTIONAL DESCRIPTION
FUNCTIONAL INTERNAL BLOCK DESCRIPTION
In battery applications, it is highly recommended to power
Efficiency analysis includes the following losses:
VBAT
VBAT
VBAT
VBAT
VBAT
VBAT
VBAT
VBAT
Pout (W)
Ploss On Chip (W)
Ploss Total (W)
Pin (W)
n (%)
Figure 5. Overall Efficiency Analysis
34704A overall system efficiency 84%
Vin (V)
Vout (V)
Iout_typ (A)
Iout_max (A)
DCR(m )
Cout ( F)
ESR (m
Fsw (kHz)
Lout ( H)
Iin_typ (A)
Iin_max (A)
ILout_peak (A)
ICout_RMS (A)
Pout (W)
Ploss On Chip (W)
Ploss Total (W)
Pin (W)
n (%)
REG1
REG2
REG3
REG4
REG5
REG6
REG7
REG8
Overall System
V1 (5.0V)
V2 (2.8 / 3.3V)
V3 (1.2V / 1.5V / 1.8V)
V4 (1.8V / 2.5V)
V5 (3.3V)
V6 (15V)
V7 (-7.0V)
V8 (15V)
84.00%
3.340
0.369
0.41
3.75
91.90%
REG1
0.100
0.500
0.154
0.540
0.724
0.212
0.500
0.042
0.044
0.544
1500
3.60
5.00
9.00
1.50
230
22
93.12%
REG2
0.200
0.500
0.201
0.502
0.510
0.005
0.660
0.047
0.049
0.709
1500
3.60
3.30
9.00
1.50
230
22
81.48%
REG3
0.150
0.550
0.063
0.209
0.649
0.074
0.180
0.038
0.041
0.221
1500
3.60
1.20
9.00
1.50
230
22
• MOSFET Switching Losses (Except for REG7 due to
• MOSFET Gate Charging Losses
• MOSFET Deadtime Losses
• External Diode Losses (Only for REG7)
• Inductor Winding DC Losses
• Inductor Core Losses (Assumed to be 20% of DC Losses
• Output AC Losses
Li-Ion Efficiency Analysis
powered directly with 3.6V nominal, battery voltage.
frequency of 1.5MHz and 1.0MHz for F
respectively, in this configuration. As a result, the following
numbers are valid for worst case operation conditions.
regulator with V2 at 3.3V, V3 at 1.2V, and V4 at 1.8V. This is
taken at the specified typical loads on Page15:
85.91%
REG4
0.100
0.300
0.059
0.178
0.444
0.076
0.180
0.028
0.030
0.210
1500
3.60
1.80
9.00
1.50
310
external MOSFET and board layout dependence)
as a rule of thumb)
In this configuration, all of the regulators are supplied or
Efficiency was calculated using the maximum allowed
The following table shows the detailed analysis for each
22
93.33%
0.0006
Pout (W)
Ploss On Chip (W)
Ploss Total (W)
Pin (W)
n (%)
REG5
0.150
0.500
0.150
0.501
0.512
0.495
0.034
0.035
0.530
1500
3.60
3.30
9.00
1.50
230
22
34704B overall system efficiency 89%
60.00%
REG6
0.050
0.060
0.254
0.304
0.444
0.071
0.750
0.135
0.145
0.895
1000
3.60
9.00
4.70
230
15
22
Analog Integrated Circuit Device Data
69.00%
REG7
0.050
0.060
0.107
0.128
0.443
0.129
0.350
0.000
0.027
0.377
1000
3.60
9.00
4.70
230
22
-7
Overall System
Freescale Semiconductor
64.00%
REG8
0.015
0.030
0.077
0.154
0.297
0.043
0.225
0.045
0.047
0.272
1000
89.6%
3.60
9.00
4.70
0.192
0.202
1.942
SW1
230
1.74
15
22
and F
SW2
,