FEATURES
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LTC7852/LTC7852-1
Dual Output, 6-Phase,
Multiphase Current Mode Synchronous
Controller with Current Monitoring
DESCRIPTION
The
LTC
®
7852/LTC7852-1
is a six-phase, dual output
current mode synchronous step-down switching regu-
lator controller that works in conjunction with external
power train devices such as DrMOS, power blocks or
discrete N-channel MOSFETs and associated gate drivers.
Its flexible design enables 1-, 2-, 3-, 4-, 5-, and 6-phase
configurations. The LTC7852 offers a unique feature that
enhances the signal-to-noise ratio of the current sense
signal, allowing the use of inductors with very low DC
winding resistances for maximum efficiency. The controller
achieves a minimum on-time of just 40ns, permitting the
use of high switching frequency at high step-down ratios.
8-, 10- or 12 phases with two ICs can be paralleled for
very high current requirements up to 400A.
The remote sense differential amplifiers and a precise
reference provide accurate output voltages between 0.5V
and 2.0V. The input voltage is not limited by the controller.
Hiccup mode protection from output shorts or overcurrent
minimizes the thermal dissipation.
The LTC7852-1 is designed specifically for DrMOS with
an internal current sense signal.
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Sub-Milliohm DCR Sensing or DrMOS with Current
Sense Improves Efficiency
Operates with Power Blocks, DrMOS or External
Gate Drivers and MOSFETs
±0.5% Total Output Voltage Accuracy
Flexible Phase Configuration
Dual Output Current Monitoring
t
ON(MIN)
= 40ns, Capable of Very Low Duty Cycles at
High Frequency
Dual Differential Remote Sensing Amplifiers
Programmable Frequency Range of 250kHz to 1.2MHz
V
IN
Range Is Not Limited by IC
V
CC
Range: 4.5V to 5.5V
V
OUT
Range: 0.5V to 2.0V
48 Lead (5mm × 6mm) GQFN for LTC7852
36 Lead (4mm × 5mm) QFN for LTC7852-1
Computer Systems
Telecom and Datacom Systems
DC Power Distribution Systems
APPLICATIONS
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All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. patents, including 9525351, 9793800, 10848051.
TYPICAL APPLICATION
V
IN
5V TO 13V
+
V
CC
4.5V TO 5.5V
4.7µF
V
CC
V
DD
PGOOD2
PWM5-6
2.2µF
L4~5
0.25µH
V
OUT1
0.9V
120A
L1~4
0.25µH
PGOOD1
DrMOS
PWM1-4
+
DrMOS
330µF
×12
+
LTC7852
SNSP1-4
220nF
220nF
SNSAVG1-4
SNSAVG5-6
2.32k
SNSN1-4
VOSNS1+
VOSNS1–
3.01k
3.3nF
150pF
0.22µF
ITH1
SS1
ILIM1 FREQ GND PHCFG ILIM2
78521 TA01a
330µF
X6
V
OUT2
1.2V
60A
715
SNSP5-6
220nF
220nF 715
16k
2.32k
SNSN5-6
VOSNS2+
VOSNS2–
28k
20k PINS NOT SHOWN
IN THIS CIRCUIT:
IMON1
IMON2
V1P5
PLLIN
CLKOUT
RUN1
RUN2
3.01k
ITH2
SS2
0.22µF
150pF
3.3nF
20k
37.4k
Rev. B
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1
LTC7852/LTC7852-1
TABLE OF CONTENTS
Features ............................................................................................................................ 1
Applications ....................................................................................................................... 1
Typical Application ............................................................................................................... 1
Description......................................................................................................................... 1
Absolute Maximum Ratings ..................................................................................................... 3
Order Information ................................................................................................................. 3
Electrical Characteristics ........................................................................................................ 4
Typical Performance Characteristics .......................................................................................... 6
Pin Functions ...................................................................................................................... 8
Functional Block Diagrams ...................................................................................................... 9
Operation..........................................................................................................................11
Applications Information .......................................................................................................15
Typical Applications .............................................................................................................27
Package Description ............................................................................................................29
Revision History .................................................................................................................31
Typical Application ..............................................................................................................32
Related Parts .....................................................................................................................32
Rev. B
2
For more information
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LTC7852/LTC7852-1
ABSOLUTE MAXIMUM RATINGS
(Note 1)
RUN1,2, PGOOD1,2, V
CC
Voltage ................. –0.3V to 6V
SNSN, SNS
AVG
(LTC7852 Only),
SNSP ............................................–0.3V to (V
CC
+ 0.3V)
All Other Pin Voltages ...................–0.3V to (V
CC
+ 0.3V)
Operating Junction Temperature Range ... –40° to 125°C
Storage Temperature Range .................. –65°C to 150°C
PIN CONFIGURATION
LTC7852
TOP VIEW
CLKOUT
PWM6
PWM5
PWM4
PWM3
PWM2
PWM1
PLLIN
GND
V
DD
LTC7852-1
SNS
AVG4
1
SNSP4 2
SNSN4 3
SNS
AVG5
4
SNSP5 5
SNSN5 6
SNS
AVG6
7
SNSP6 8
SNSN6 9
PGOOD2 10
SS2 11
ITH2 12
V
OSNS2–
13
V
OSNS2+
14
15 16 17 18 19 20 21 22 23 24
ILIM2
IMON2
IMON1
PHCFG
ILIM1
RUN2
V1P5
FREQ
RUN1
V
CC
49
49
49
GND
49
49
38 SNS
AVG3
37 SNSP3
36 SNSN3
35 SNS
AVG2
34 SNSP2
33 SNSN2
32 SNS
AVG1
31 SNSP1
30 SNSN1
29 PGOOD1
28 SS1
27 ITH1
26 V
OSNS1–
25 V
OSNS1+
PLLIN
SNSN
SNSP4
SNSP5
SNSP6
PGOOD2
SS2
ITH2
V
OSNS2
–
36 35 34 33 32 31 30 29
1
2
3
4
5
6
7
8
9
11 12 13 14 15 16 17 18
PHCFG
ILIM1
FREQ
RUN1
ILIM2
RUN2
GND
V
CC
37
GND
28 V
DD
27 SNSP3
26 SNSP2
25 SNSN
24 SNSP1
23 PGOOD1
22 SS1
21 ITH1
20 V
OSNS1–
19 V
OSNS1+
V
OSNS2+
10
UFD PACKAGE
36-LEAD (4mm
×
5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W
RHE PACKAGE
48-LEAD (5mm × 6mm) PLASTIC GQFN
T
JMAX
= 125°C,
θ
JA
= 30°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC7852ERHE#PBF
LTC7852IRHE#PBF
LTC7852EUFD-1#PBF
LTC7852IUFD-1#PBF
TAPE AND REEL
LTC7852ERHE#TRPBF
LTC7852IRHE#TRPBF
LTC7852EUFD-1#TRPBF
LTC7852IUFD-1#TRPBF
PART MARKING
7852
7852
78521
78521
PACKAGE DESCRIPTION
48-LEAD (5mm x 6mm) Plastic GQFN
48-LEAD (5mm x 6mm) Plastic GQFN
36-LEAD (4mm x 5mm) Plastic QFN
36-LEAD (4mm x 5mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
Contact the factory for parts specified with wider operating temperature ranges.
Tape and reel specifications.
Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
Rev. B
CLKOUT
PWM6
PWM5
PWM4
PWM3
PWM2
PWM1
48 47 46 45 44 43 42 41 40 39
GND
TOP VIEW
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3
LTC7852/LTC7852-1
The
l
denotes the specifications which apply over the specified operating
temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
CC
= V
RUN
= 5V unless otherwise specified.
SYMBOL
V
CC
Minimum
V
OUT
V
OSNS+
I
OSNS+
V
REFLNREG
V
LOADREG
g
m1,2
f
0dB
V
OVL
I
Q
UVLO
UVLO
HYS
I
SNSAVG
I
SNSP
I
SS
V
SNSN
A
VT_SNS
V
RUN
V
RUN_HYS
I
RUN
V
SENSE(MAX)
PARAMETER
Bias Supply Input
Output Voltage Range
Regulated Feedback Voltage
Feedback Current
Reference Voltage Line Reg.
Output Voltage Load
Regulation
Transconductance Amplifier
g
m
Differential Amplifier Unity-
Gain Crossover Frequency
Feedback Overvoltage Lockout
Input DC Supply Current
Normal Mode
Shutdown
Undervoltage Lockout
UVLO Hysteresis
Sense Pin Bias Currents
Sense Pin Bias Currents
Soft-Start Charge Current
Sense Pin Bias Voltage
Total Sense Signal Gain to
Current Comparator
RUN Pin ON Threshold
RUN Pin ON Hysteresis
RUN Pin Pull-Up Current
RUN < ON Threshold
RUN > ON Threshold
Maximum Current Sense
Threshold
CONDITIONS
LTC7852 Only (Note 2)
ITH = 1.2V (Note 4)
–40°C to 125°C
0°C to 85°C
V
CC
= 4.5V to 5.5V
ΔI
TH
= 0.7V to 1.2V
ΔI
TH
= 1.2V to 1.6V
I
TH
=1.7V, Sink/Source 10µA
(Note 5)
Measured at V
OSNS+
V
RUN
= 0V
V
VCC
Falling
V
SNSAVG
= 1.0V LTC7852 Only
LTC7852 SNSP = 1.0V
LTC7852-1 SNSP = 1.5V
V
SS
= 0V
–3mA < I
SNSN
< 3mA
LTC7852-1 Only
LTC7852 Only
V
RUN
Rising
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ELECTRICAL CHARACTERISTICS
MIN
TYP
MAX
4.5
2.0
UNITS
V
V
mV
mV
nA
%
%
%
mmho
MHz
496
498
500
500
l
l
0.01
0.01
2.75
4
5
7.5
15
1.2
4.0
200
504
502
–100
0.1
0.1
0.1
10
%
mA
mA
V
mV
nA
nA
µA
V
V/V
3.6
4.3
±30
±50
–4.5
–5
1.5
5
–5.5
l
1.1
1.22
140
–1.3
–7.7
1.34
V
mV
µA
µA
V
ØMIS
Standard
Deviation of
t
ON(MIN)
Phase to Phase Current
Sensed Voltage Mismatching
Minimum On-Time
RUN < 1.1V
RUN > 1.34V
LTC7852
I
TH
= 2.2V, V
SNSN
=1.0V
V
SNSAVG
= V
SNSN
I
LIM
= 0V
I
LIM
= 1/4V
CC
I
LIM
= Float
I
LIM
= 3/4V
CC
I
LIM
= V
CC
LTC7852-1
I
TH
= 2.2V
I
LIM
= 0V
I
LIM
= 1/4Vcc
I
LIM
= Float
I
LIM
= 3/4V
CC
I
LIM
= V
CC
I
LIM
= Float, PHCFG = Float
I
TH
= 2.2V
(Note 6)
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9
14
19
24
28.5
45
70
95
120
142.5
10
15
20
25
30
50
75
100
125
150
0.5
40
11
16
21
26
31.5
55
80
105
130
157.5
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
ns
Rev. B
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For more information
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LTC7852/LTC7852-1
The
l
denotes the specifications which apply over the specified operating
temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
CC
= V
RUN
= 5V unless otherwise specified.
SYMBOL
Power Good
V
PGOOD(ON)
I
PGOOD(OFF)
t
PGOOD
V
PGD
V
PG1(HYST)
f
OSC
PGOOD Pull Down Resistance
PGOOD Leakage Current
V
PGOOD
High to Low Delay
PGOOD Trip Level
V
FB
with Respect to Set Output Voltage
V
FB
Ramping Up
V
FB
Ramping Down
5
–5
V
PGOOD
= 5V
45
7.5
–7.5
15
R
FREQ
= 30.1kΩ
R
FREQ
= 47.5kΩ
R
FREQ
= 54.9kΩ
R
FREQ
= 75.0kΩ
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ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
MIN
TYP
MAX
200
2
UNITS
Ω
µA
µs
10
–10
%
%
mV
PGOOD Trip Level Hysteresis
Oscillator Frequency
215
550
675
0.875
0.25
–18.5
Oscillator and Phase-Locked Loop
250
600
750
1.05
20
200
V
PLLIN
Rising
V
PLLIN
Falling
I
LOAD
= 500µA
I
LOAD
= –500µA
2
1.2
0.2
5
3.3
I
LOAD
= –500µA
I
LOAD
= 500µA
PWM = 0V
PWM = 3.3V
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285
650
825
1.225
1.2
–21.5
kHz
kHz
kHz
MHz
MHz
µA
kΩ
V
V
V
V
V
Sync. Freq. Range
I
FREQ
R
PLLIN
V
PLLIN
V
CLKOUT
V
DD
Output
V
DD
PWM Outputs
PWM
PWM Output High Voltage
PWM Output Low Voltage
PWM Output Current in Hi-Z
State
IMON Outputs (LTC7852 Only)
V1P5
IMON
1.5V Regulator Output Voltage V
SNS
= 0, –3mA < I
V1P5
< 3mA
IMON Output Voltage
V
SNS
= V
SNSMAX
, I
LIM
= Float
Internal V
DD
Voltage
FREQ Pin Output Current
PLLIN Input Resistance
PLLIN Input Threshold
Low Output Voltage
High Output Voltage
V
FREQ
= 0.8V
3.1
3.3
3.5
0.5
–1
1
V
V
µA
µA
V
mV
1.4
V1P5 +142.5
1.5
V1P5 +150
1.6
V1P5 +157.5
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
The LTC7852/LTC7852-1 is tested under pulsed load conditions
such that T
J
≈ T
A
. The LTC7852E/LTC7852-1E is guaranteed to meet
performance specifications from 0°C to 85°C operating junction
temperature. Specifications over the –40°C to 125°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC7852I/LTC7852-1I
is guaranteed to meet performance specifications over the full –40°C
to 125°C operating junction temperature range. The maximum ambient
temperature consistent with these specifications is determined by specific
operating conditions in conjunction with board layout, the package thermal
impedance and other environmental factors.
T
J
is calculated from the ambient temperature, T
A
, and power dissipation,
P
D
, according to the following formula:
LTC7852RHE: T
J
= T
A
+ (P
D
• 30°C/W)
LTC7852UFD-1: T
J
= T
A
+ (P
D
• 43°C/W)
Note 3:
Output voltage range of LTC7852-1 is determined by the DrMOS.
Note 4:
The LTC7852/LTC7852-1 is tested in a feedback loop that servos
V
ITH
to a specified voltage and measures the resultant V
FB
.
Note 5:
Guaranteed by design.
Note 6:
The minimum on-time condition is specified for an inductor
peak-to-peak ripple current >40% of I
MAX
(See Minimum On-Time
Considerations in the Applications Information section).
Rev. B
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