1/33
L6917B
September 2002
s
2 PHASE OPERATION WITH
SYNCRHONOUS RECTIFIER CONTROL
s
ULTRA FAST LOAD TRANSIENT RESPONSE
s
INTEGRATED HIGH CURRENT GATE
DRIVERS: UP TO 2A GATE CURRENT
s
TTL-COMPATIBLE 5 BIT PROGRAMMABLE
OUTPUT COMPLIANT WITH VRM 9.0
s
0.8% INTERNAL REFERENCE ACCURACY
s
10% ACTIVE CURRENT SHARING
ACCURACY
s
DIGITAL 2048 STEP SOFT-START
s
OVERVOLTAGE PROTECTION
s
OVERCURRENT PROTECTION REALIZED
USING THE LOWER MOSFET'S R
dsON
OR A
SENSE RESISTOR
s
300 kHz INTERNAL OSCILLATOR
s
OSCILLATOR EXTERNALLY ADJUSTABLE
UP TO 600kHz
s
POWER GOOD OUTPUT AND INHIBIT
FUNCTION
s
REMOTE SENSE BUFFER
s
PACKAGE: SO-28
APPLICATIONS
s
POWER SUPPLY FOR SERVERS AND
WORKSTATIONS
s
POWER SUPPLY FOR HIGH CURRENT
MICROPROCESSORS
s
DISTRIBUTED DC-DC CONVERTERS
DESCRIPTION
The device is a power supply controller specifically
designed to provide a high performance DC/DC con-
version for high current microprocessors.
The device implements a dual-phase step-down con-
troller with a 180 phase-shift between each phase.
A precise 5-bit digital to analog converter (DAC) al-
lows adjusting the output voltage from 1.100V to
1.850V with 25mV binary steps.
The high precision internal reference assures the se-
lected output voltage to be within 0.8%. The high
peak current gate drive affords to have fast switching
to the external power mos providing low switching
losses.
The device assures a fast protection against load
over current and load over/under voltage. An internal
crowbar is provided turning on the low side mosfet if
an over-voltage is detected. In case of over-current,
the system works in Constant Current mode.
SO-28
ORDERING NUMBERS:L6917BD
L6917BDTR (Tape & Reel)
5 BIT PROGRAMMABLE DUAL-PHASE CONTROLLER
BLOCK DIAGRAM
CURRENT
READING
CURRENT
READING
IFB
TOTAL
CURRENT
AVG
CURRENT
CH 1 OVER
CURRENT
CH 2 OVER
CURRENT
DAC
DIGITAL
SOFT START
L
OGI
C
P
W
M
AD
AP
T
I
VE AN
T
I
CRO
S
S
-
C
O
NDUCT
I
O
N
L
OGI
C
P
W
M
AD
AP
T
I
VE AN
T
I
CRO
S
S
-
C
O
NDUCT
I
O
N
CH1 OVER
CURRENT
CH2 OVER
CURRENT
LOGIC
AND
PROTECTIONS
2 PHASE
OSCILLATOR
PWM1
CU
RR
E
N
T
CO
R
R
E
C
T
I
O
N
PWM2
CU
RR
E
N
T
CO
R
R
E
C
T
I
O
N
ERROR
AMPLIFIER
REMOTE
BUFFER
10k
10k
10k
LS
LS
HS
Vcc
HS
BOOT1
UGATE1
PHASE1
LGATE1
ISEN1
PGNDS1
PGND
PGNDS2
ISEN2
LGATE2
PHASE2
UGATE2
BOOT2
Vcc
COMP
FB
VSEN
FBG
FBR
VID0
VID1
VID2
VID3
VID4
PGOOD
ROSC / INH
SGND
VCCDR
10k
< >
+
-
+
+
-
VCCDR
VCC
L6917B
2/33
ABSOLUTE MAXIMUM RATINGS
THERMAL DATA
PIN CONNECTION
Symbol
Parameter
Value
Unit
Vcc, V
CCDR
to PGND
15
V
V
BOOT
-V
PHASE
Boot Voltage
15
V
V
UGATE1
-V
PHASE1
V
UGATE2
-V
PHASE2
15
V
LGATE1, PHASE1, LGATE2, PHASE2 to PGND
-0.3 to Vcc+0.3
V
All other pins to PGND
-0.3 to 7
V
V
phase
Sustainable Peak Voltage t < 20ns @ 600kHz
26
V
Symbol
Parameter
Value
Unit
R
th j-amb
Thermal Resistance Junction to Ambient
60
C/W
T
max
Maximum junction temperature
150
C
T
storage
Storage temperature range
-40 to 150
C
T
j
Junction Temperature Range
-25 to 125
C
P
MAX
Max power dissipation at T
amb
= 25C
2
W
LGATE1
VCCDR
PHASE1
VID3
VID2
VID1
FB
BOOT1
UGATE1
VID4
BOOT2
PGOOD
UGATE2
PHASE2
LGATE2
PGND
1
3
2
4
5
6
7
8
9
18
17
16
15
19
20
10
VSEN
VCC
GND
COMP
SO28
11
12
13
14
24
23
22
21
25
26
27
28
FBG
ISEN1
PGNDS1
FBR
OSC / INH / FAULT
ISEN2
PGNDS2
VID0
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L6917B
ELECTRICAL CHARACTERISTICS
V
CC
= 12V 10%, T
J
= 0 to 70C unless otherwise specified
Symbol
Parameter
Test Condition
Min
Typ
Max
Unit
Vcc SUPPLY CURRENT
I
CC
Vcc supply current
HGATEx and LGATEx open
V
CCDR
=V
BOOT
=12V
7.5
10
12.5
mA
I
CCDR
V
CCDR
supply current
LGATEx open; V
CCDR
=12V
2
3
4
mA
I
BOOTx
Boot supply current
HGATEx open; PHASEx to PGND
V
CC
=V
BOOT
=12V
0.5
1
1.5
mA
POWER-ON
Turn-On V
CC
threshold
V
CC
Rising; V
CCDR
=5V
7.8
9
10.2
V
Turn-Off V
CC
threshold
V
CC
Falling; V
CCDR
=5V
6.5
7.5
8.5
V
Turn-On V
CCDR
Threshold
V
CCDR
Rising
V
CC
=12V
4.2
4.4
4.6
V
Turn-Off V
CCDR
Threshold
V
CCDR
Falling
V
CC
=12V
4.0
4.2
4.4
V
OSCILLATOR/INHIBIT/FAULT
f
OSC
Initial Accuracy
OSC = OPEN
OSC = OPEN; Tj=0
C to 125
C
278
270
300
322
330
kHz
kHz
f
OSC,Rosc
Total Accuracy
R
T
to GND=74k
450
500
550
kHz
INH
Inhibit threshold
I
SINK
=5mA
0.8
0.85
0.9
V
d
MAX
Maximum duty cycle
OSC = OPEN
70
75
%
Vosc
Ramp Amplitude
1.8
2
2.2
V
FAULT
Voltage at pin OSC
OVP or UVP Active
4.75
5.0
5.25
V
REFERENCE AND DAC
Output Voltage
Accuracy
VID0, VID1, VID2, VID3, VID4
see Table1;
FBR = V
OUT
; FBG = GND
-0.8
-
0.8
%
I
DAC
VID pull-up Current
VIDx = GND
4
5
6
A
VID pull-up Voltage
VIDx = OPEN
3.1
-
3.4
V
ERROR AMPLIFIER
DC Gain
80
dB
SR
Slew-Rate
COMP=10pF
15
V/
s
DIFFERENTIAL AMPLIFIER (REMOTE BUFFER)
DC Gain
1
V/V
CMRR
Common Mode Rejection Ratio
40
dB
L6917B
4/33
Input Offset
FBR=1.100V to1.850V;
FBG=GND
-12
12
mV
SR
Slew Rate
VSEN=10pF
15
V/
s
DIFFERENTIAL CURRENT SENSING
I
ISEN1
,
I
ISEN2
Bias Current
Iload=0
45
50
55
A
I
PGNDSx
Bias Current
45
50
55
A
I
ISEN1
,
I
ISEN2
Bias Current at
Over Current Threshold
80
85
90
A
I
FB
Active Droop Current
Iload<0%
Iload=100%
47.5
0
50
1
52.5
A
A
GATE DRIVERS
t
RISE
HGATE
High Side
Rise Time
V
BOOTx
-V
PHASEx
=10V;
C
HGATEx
to PHASEx=3.3nF
15
30
ns
I
HGATEx
High Side
Source Current
V
BOOTx
-V
PHASEx
=10V 2
A
R
HGATEx
High Side
Sink Resistance
V
BOOTx
-V
PHASEx
=12V;
1.5
2
2.5
t
RISE
LGATE
Low Side
Rise Time
V
CCDR
=10V;
C
LGATEx
to PGNDx=5.6nF
30
55
ns
I
LGATEx
Low Side
Source Current
V
CCDR
=10V
1.8
A
R
LGATEx
Low Side
Sink Resistance
V
CCDR
=12V
0.7
1.1
1.5
P GOOD and OVP/UVP PROTECTIONS
PGOOD
Upper Threshold
(V
SEN
/DACOUT)
V
SEN
Rising
108
112
116
%
PGOOD
Lower Threshold
(V
SEN
/DACOUT)
V
SEN
Falling
84
88
92
%
OVP
Over Voltage Threshold
(V
SEN
)
V
SEN
Rising
2.0
2.25
V
UVP
Under Voltage Trip
(V
SEN
/DACOUT)
V
SEN
Falling
56
60
64
%
V
PGOOD
PGOOD Voltage Low
I
PGOOD
= -4mA
0.3
0.4
0.5
V
ELECTRICAL CHARACTERISTICS (continued)
V
CC
= 12V 10%, T
J
= 0 to 70C unless otherwise specified
Symbol
Parameter
Test Condition
Min
Typ
Max
Unit
5/33
L6917B
Table 1. VID Settings
VID4
VID3
VID2
VID1
VID0
Output Voltage (V)
1
1
1
1
1
OUTPUT OFF
1
1
1
1
0
1.100
1
1
1
0
1
1.125
1
1
1
0
0
1.150
1
1
0
1
1
1.175
1
1
0
1
0
1.200
1
1
0
0
1
1.225
1
1
0
0
0
1.250
1
0
1
1
1
1.275
1
0
1
1
0
1.300
1
0
1
0
1
1.325
1
0
1
0
0
1.350
1
0
0
1
1
1.375
1
0
0
1
0
1.400
1
0
0
0
1
1.425
1
0
0
0
0
1.450
0
1
1
1
1
1.475
0
1
1
1
0
1.500
0
1
1
0
1
1.525
0
1
1
0
0
1.550
0
1
0
1
1
1.575
0
1
0
1
0
1.600
0
1
0
0
1
1.625
0
1
0
0
0
1.650
0
0
1
1
1
1.675
0
0
1
1
0
1.700
0
0
1
0
1
1.725
0
0
1
0
0
1.750
0
0
0
1
1
1.775
0
0
0
1
0
1.800
0
0
0
0
1
1.825
0
0
0
0
0
1.850
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