LTC3735 Datasheet, PDF (28/32 Pages) Linear Technology – 2-Phase, High Efficiency DC/DC Controller for Intel Mobile CPUs

LTC3735
TYPICAL APPLICATION
Figure 14 shows a typical application using the LTC3735
to power the mobile CPU core. The input can vary from
5V to 24V; the output voltage can be programmed from
0.7V to 1.708V with a maximum current of 32A. By only
modifying the external MOSFET and inductor selection,
higher load current capability (up to 40A) can be achieved.
The power supply in Figure 14 receives a VRON signal for
ON/OFF control. After soft-start, the output voltage is set
at 1.2V until the assertion of the MCH_PG signal. After
about a 50µs delay, the VID5-VID0 bits gain the control
over the output voltage and program it between 0.7V and
1.708V. When the STP_CPUB signal is low, a deep sleep
state is indicated and the output voltage is decreased by
about 1.04%. When the DPRSLPVR signal is high, a deeper
sleep state is indicated and the output voltage becomes
0.748V regardless of the states of the VID bits. Active
voltage positioning is accomplished with a resistor from
the I_TH to the V_OA+ pin. Lower resistance yields a steeper
AVP slope while higher resistance provides a flatter slope.
Finally, the PGOOD output is masked for 110µs during VID
change or state transition.
3.3V
2k
PGOOD
5V
100k
Si1034X
V_RON
V_OA⁺
232k
100pF
470pF
3.3k
1µF
X5R
5V
4.7µF
X5R
V_CCP_PG/MCH_PG
DPRSLPVR
36
MCH_PG
2
DPRSLPVR
33
TG1
32
SW1
STP_CPUB
8
STP_CPUB
27
BG1
4
PSIB
PSIB
26
PGND
3 _{FREQSET SENSE1+} 10
19
VID0
VID0
SENSE1^{– 11}
20
VID1
VID1
21
LTC3735
30
VID2
VID2
TG2
22
VID3
VID3
29
SW2
23
VID4
VID4
25
BG2
24
VID5
VID5
35
PGOOD
SENSE2^{+ 12}
1000pF
17
I_TH
SENSE2^{– 13}
16
18
RUN/SS RBOOT
1M ^470pF 9
14
SGND RDPRSLP
47pF
V_OUT
1
V_FB
28
PV_CC
34
BOOST1
15
RDPSLP
V_OA+ ⁵
7
OAOUT
31
BOOST2
V_OA– ⁶
BAT54
0.1µF
SW2
0.1µF
SW1
Q1
Q2
1nF
Q3
Q4
1nF
12.7k
56.2k
1.27M
13.3k
1µF L1
0.8µH _0.002Ω
S1⁺
D1
10Ω 10Ω
C1
10µF ×4
35V X5R
1µF L2
0.8µH
D2
0.002Ω
S2⁺
10Ω
10Ω
13.3k
2.2µF
+ _C5
×3
C5: PANSONIC SP CAPS EEFSX0D181R
OR SANYO POSCAP 2R5TPE220M9
D1, D2: B340A
L1, L2: CDEP 104-OR8MC-L
Q1, Q3: IRF7811W OR Si7860DP
Q2, Q4: IRF7811W ¥2 OR Si7856DP
V_IN
5V ~ 24V
V_OUT
0.7V ~ 1.708V
AT 32A
100Ω 100Ω
V_OA+
S1⁺
S2⁺
1M 1%
PSIB
549k
3.3V
3.3V CLK_EN# 3.3V
1M
2N7002
249k
MMBT3904
80.6k
2k
4.12k
43.2k
1µF
1.9k
IMVP4_PG
MMBT3904
PGOOD
BAT54C
V_RON
3735 F14
Figure 14. 5V to 24V Input, 0.7V to 1.708V Output, 32A IMVP-IV Compatible Power Supply
3735fa
28