The CS5155 is a 5-bit synchronous
dual N-Channel buck controller. It
is designed to provide unprece-
dented transient response for
todays demanding high-density,
high-speed logic. The regulator
operates using a proprietary control
method, which allows a 100ns
response time to load transients.
The CS5155 is designed to operate
over a 4.25-14V range (V
CC
) using
12V to power the IC and 5V as the
main supply for conversion.
The CS5155 is specifically designed
to power Pentium
II processors
and other high performance core
logic. It includes the following fea-
tures: on board, 5-bit DAC, short
circuit protection, 1.0% output tol-
erance, V
CC
monitor, and pro-
grammable soft start capability. The
CS5155 is backwards compatible
with the 4 bit CS-5150, allowing the
mother board designer the capabili-
ty of using either the CS-5150 or the
CS5155 with no change in layout.
The CS5155 is available in 16 pin
surface mount and DIP packages.
Features
s
Dual N-Channel Design
s
Excess of 1MHz Operation
s
100ns Transient Response
s
5-Bit DAC
s
Backward Compatible with
4 Bit CS-5150/5151 and
Adjustable CS-5120/5121
s
30ns Gate Rise/Fall Times
s
1% DAC Accuracy
s
5V & 12V Operation
s
Remote Sense
s
Programmable Soft Start
s
Lossless Short Circuit
Protection
s
V
CC
Monitor
s
25ns FET Nonoverlap Time
s
Adaptive Voltage
Positioning
s
V
2
Control Topology
s
Current Sharing
s
Overvoltage Protection
Package Options
CPU 5-Bit Synchronous Buck Controller
CS5155
Description
Application Diagram
1
V
ID0
V
ID1
V
ID2
V
ID3
SS
V
ID4
C
OFF
V
FFB
V
FB
COMP
LGnd
V
CC1
V
GATE(L)
PGnd
V
GATE(H)
V
CC2
16 Lead SO Narrow & PDIP
1
Switching Power Supply for core logic - Pentium
II processor
0.33
mF
V
ID0
V
ID1
V
ID2
V
ID3
V
ID0
V
ID1
V
ID2
V
ID3
V
CC1
SS
CS5155
C
OFF
LGnd
V
FB
V
FFB
COMP
IRL3103
IRL3103
0.1
mF
12V
5V
2
mH
1.3V to 3.5V @ 13A
V
CC2
V
GATE(H)
V
GATE(L)
PGnd
1200
mF/16V x 3
AlEl
3.3k
0.1
mF
1200
mF/16V x 5
AlEl
100pF
330pF
V
ID4
V
ID4
V
2
is a trademark of Switch Power, Inc.
Pentium is a registered trademark of Intel Corporation.
CS5155
Rev. 1/22/99
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: (401)885-3600 Fax: (401)885-5786
Email: info@cherry-semi.com
Web Site: www.cherry-semi.com
A Company
2
Pin Name
Max Operating Voltage
Max Current
V
CC1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25mA DC/1.5A peak
V
CC2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20mA DC/1.5A peak
SS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-100A
COMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200A
V
FB
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.2A
C
OFF
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.2A
V
FFB
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.2A
V
ID0
- V
ID4
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-50A
V
GATE(H)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100mA DC/1.5A peak
V
GATE(L)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100mA DC/1.5A peak
LGnd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25mA
PGnd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100mA DC/1.5A peak
Operating Junction Temperature, T
J
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0 to 150C
Lead Temperature Soldering
Wave Solder (through hole styles only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 sec. max, 260C peak
Reflow (SMD styles only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60 sec. max above 183C, 230C peak
Storage Temperature Range, T
S
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65 to 150C
ESD Susceptibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2kV
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
CS5155
Electrical Characteristics: 0C < T
A
< +70C; 0C < T
J
< +85C; 8V < V
CC1
< 14V; 5V < V
CC2
< 20V;
DAC Code: V
ID4
= V
ID2
= V
ID1
= V
ID0
= 1; V
ID3
= 0; CV
GATE(L)
and CV
GATE(H)
= 1nF; C
OFF
= 330pF; C
SS
= 0.1F, unless otherwise specified.
Absolute Maximum Ratings
s Error Amplifier
V
FB
Bias Current
V
FB
= 0V
0.3
1.0
A
Open Loop Gain
1.25V < V
COMP
< 4V; Note 1
50
60
dB
Unity Gain Bandwidth
Note 1
500
3000
kH
COMP SINK Current
V
COMP
= 1.5V; V
FB
= 3V; V
SS
> 2V
0.4
2.5
8.0
mA
COMP SOURCE Current
V
COMP
= 1.2V; V
FB
= 2.7V; V
SS
= 5V
30
50
70
A
COMP CLAMP Current
V
COMP
= 0V; V
FB
= 2.7V
0.4
1.0
1.6
mA
COMP High Voltage
V
FB
= 2.7V; V
SS
= 5V
4.0
4.3
5.0
V
COMP Low Voltage
V
FB
=3V 160
300
mV
PSRR
8V < V
CC1
< 14V @ 1kHz; Note 1
60
85
dB
s V
CC1
Monitor
Start Threshold
Output switching
3.75
3.90
4.05
V
Stop Threshold
Output not switching
3.70
3.85
4.00
V
Hysteresis
Start-Stop
50
mV
s DAC
Input Threshold
V
ID0
, V
ID1
, V
ID2
, V
ID3
, V
ID4
1.00
1.25
2.40
V
Input Pull Up Resistance
V
ID0
, V
ID1
, V
ID2
, V
ID3
, V
ID4
25
50
100
k
Pull Up Voltage
4.85
5.00
5.15
V
Accuracy
Measure V
FB
= V
COMP
, 25C T
J
85C
1.0
%
V
ID4
V
ID3
V
ID2
V
ID1
V
ID0
0
1
1
1
1
1.3266
1.3400
1.3534
V
0
1
1
1
0
1.3761
1.3900
1.4039
V
0
1
1
0
1
1.4256
1.4400
1.4544
V
0
1 1
0
0
1.4751
1.4900
1.5049
V
CS5155
3
Electrical Characteristics: 0C < T
A
< +70C; 0C < T
J
< +85C; 8V < V
CC1
< 14V; 5V < V
CC2
< 20V;
DAC Code: V
ID4
= V
ID2
= V
ID1
= V
ID0
= 1; V
ID3
= 0; CV
GATE(L)
and CV
GATE(H)
= 1nF; C
OFF
= 330pF; C
SS
= 0.1F, unless otherwise specified.
s DAC: continued
V
ID4
V
ID3
V
ID2
V
ID1
V
ID0
0
1
0
1
1
1.5246
1.5400
1.5554
V
0
1
0
1
0
1.5741
1.5900
1.6059
V
0
1
0
0
1
1.6236
1.6400
1.6564
V
0
1 0
0
0
1.6731
1.6900
1.7069
V
0
0 1
1
1
1.7226
1.7400
1.7574
V
0
0
1 1
0
1.7721
1.7900
1.8079
V
0
0
1
0
1
1.8216
1.8400
1.8584
V
0
0
1
0
0
1.8711
1.8900
1.9089
V
0
0
0
1
1
1.9206
1.9400
1.9594
V
0
0
0
1
0
1.9701
1.9900
2.0099 V
0
0
0
0
1
2.0196
2.0400
2.0604
V
0
0 0
0
0
2.0691
2.0900
2.1109
V
1
1
1
1
1
1.2315
1.2440
1.2564
V
1
1
1
1
0
2.1186
2.1400
2.1614
V
1
1
1
0
1
2.2176
2.2400
2.2624
V
1
1
1
0
0
2.3166
2.3400
2.3634
V
1
1
0
1
1
2.4156
2.4400
2.4644
V
1
1
0
1
0
2.5146
2.5400
2.5654
V
1
1
0
0
1
2.6136
2.6400
2.6664
V
1
1
0
0
0
2.7126
2.7400
2.7674
V
1
0
1
1
1
2.8116
2.8400
2.8684
V
1
0
1
1
0
2.9106
2.9400
2.9694
V
1
0
1
0
1
3.0096
3.0400
3.0704
V
1
0
1
0
0
3.1086
3.1400
3.1714
V
1
0
0
1
1
3.2076
3.2400
3.2724
V
1
0
0
1
0
3.3066
3.3400
3.3734
V
1
0
0
0
1
3.4056
3.4400
3.4744
V
1
0
0
0
0
3.5046
3.5400
3.5754
V
s V
GATE(H)
and V
GATE(L)
Out SOURCE Sat at 100mA
Measure V
CC1
V
GATE(L),
;V
CC2
V
GATE(H)
1.2
2.0
V
Out SINK Sat at 100mA
Measure V
GATE(H)
VPGnd;
1.0
1.5
V
V
GATE(L)
VPGnd
Out Rise Time
1V < V
GATE(H)
< 9V; 1V < V
GATE(L)
< 9V
30
50
ns
V
CC1
= V
CC2
= 12V
Out Fall Time
9V > V
GATE(H)
> 1V; 9V > V
GATE(L)
> 1V
30
50
ns
V
CC1
= V
CC2
= 12V
Shoot-Through Current
Note 1
50
mA
Delay V
GATE(H)
to V
GATE(L)
V
GATE(H)
falling to 2V; V
CC1
= V
CC2
= 8V
25
50
ns
V
GATE(L)
rising to 2V
Delay V
GATE(L)
to V
GATE(H)
V
GATE(L)
falling to 2V; V
CC1
= V
CC2
= 8V
25
50
ns
V
GATE(H)
rising to 2V
V
GATE(H)
, V
GATE(L)
Resistance
Resistor to LGnd
20
50
100
k
V
GATE(H)
, V
GATE(L)
Schottky
LGnd to V
GATE(H)
@ 10mA
600
800
mV
LGnd to V
GATE(L)
@ 10mA
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
4
CS5155
Package Pin Description
PACKAGE PIN #
PIN SYMBOL
FUNCTION
16L SO Narrow & PDIP
1,2,3,4,6
V
ID0
V
ID4
Voltage ID DAC input pins. These pins are internally pulled up to 5V
providing logic ones if left open. V
ID4
selects the DAC range. When V
ID4
is High (logic one), the DAC range is 2.14V to 3.54V with 100mV incre-
ments. When V
ID4
is Low (logic zero), the DAC range is 1.34V to 2.09V
with 50mV increments. V
ID0
- V
ID4
select the desired DAC output volt-
age. Leaving all 5 DAC input pins open results in a DAC output voltage
of 1.244V, allowing for adjustable output voltage, using a traditional
resistor divider.
5
SS
Soft Start Pin. A capacitor from this pin to LGnd in conjunction with
internal 60A current source provides soft start function for the con-
troller. This pin disables fault detect function during Soft Start. When a
fault is detected, the soft start capacitor is slowly discharged by internal
2A current source setting the time out before trying to restart the IC.
Charge/discharge current ratio of 30 sets the duty cycle for the IC when
the regulator output is shorted.
s Soft Start (SS)
Charge Time
1.6
3.3
5.0
ms
Pulse Period
25
100
200
ms
Duty Cycle
(Charge Time/Pulse Period)
100
1.0
3.3
6.0
%
COMP Clamp Voltage
V
FB
= 0V; V
SS
= 0
0.50
0.95
1.10
V
V
FFB
SS Fault Disable
V
GATE(H)
= Low; V
GATE(L)
= Low
0.9
1.0
1.1
V
High Threshold
2.5
3.0
V
s PWM Comparator
Transient Response
V
FFB
= 0 to 5V to V
GATE(H)
= 9V to 1V;
100
125
ns
V
CC1
= V
CC2
= 12V
V
FFB
Bias Current
V
FFB
= 0V
0.3
A
s Supply Current
I
CC1
No Switching
8.5
13.5
mA
I
CC2
No Switching
1.6
3.0
mA
Operating I
CC1
V
FB
= COMP = V
FFB
8
13
mA
Operating I
CC2
V
FB
= COMP = V
FFB
2
5
mA
s C
OFF
Normal Charge Time
V
FFB
= 1.5V; V
SS
= 5V
1.0
1.6
2.2
s
Extension Charge Time
V
SS
= V
FFB
= 0
5.0
8.0
11.0
s
Discharge Current
C
OFF
to 5V; V
FB
>1V
5.0
mA
s Time Out Timer
Time Out Time
V
FB
= V
COMP
; V
FFB
= 2V;
10
30
50
s
Record V
GATE(H)
Pulse High Duration
Fault Mode Duty Cycle
V
FFB
= 0V
35
50
65
%
Note 1: Guaranteed by design, not 100% tested in production.
Electrical Characteristics: 0C < T
A
< +70C; 0C < T
J
< +85C; 8V < V
CC1
< 14V; 5V < V
CC2
< 20V;
DAC Code: V
ID4
= V
ID2
= V
ID1
= V
ID0
= 1; V
ID3
= 0; CV
GATE(L)
and CV
GATE(H)
= 1nF; C
OFF
= 330pF; C
SS
= 0.1F, unless otherwise specified.
5
CS5155
Block Diagram
Q
V
ID1
V
CC1
SS
COMP
V
FB
V
ID0
LGnd
V
FFB
V
CC2
V
GATE(H)
PGnd
V
GATE(L)
V
ID2
V
ID3
-
+
5 BIT
DAC
C
OFF
Slow Feedback
Maximum
On-Time
Timeout
V
CC1
R
Q
S
COFF
One Shot
PWM
COMP
SS High
Comparator
FAULT
Latch
2.5V
Error
Amplifier
Fast Feedback
-
+
V
CC1
Monitor
Comparator
V
ID4
-
+
-
+
-
+
-
+
VFFB Low
Comparator
PWM
Comparator
SS Low
Comparator
R
Q
S
Q
R
Q
S
2
mA
5V
60
mA
Normal
Off-Time
Timeout
Extended
Off-Time
Timeout
Time Out
Timer
(30
ms)
Edge Triggered
Off-Time
Timeout
3.90V
3.85V
FAULT
FAULT
GATE(H) = ON
GATE(H) = OFF
PGnd
PWM
Latch
1V
0.7V
Package Pin Description: continued
PACKAGE PIN #
PIN SYMBOL
FUNCTION
16L SO Narrow & PDIP
7
C
OFF
A capacitor from this pin to ground sets the time duration for the on
board one shot, which is used for the constant off time architecture.
8
V
FFB
Fast feedback connection to the PWM comparator. This pin is connect-
ed to the regulator output. The inner feedback loop terminates on time.
9
V
CC2
Boosted power for the high side gate driver.
10
V
GATE(H)
High FET driver pin capable of 1.5A peak switching current. Internal
circuit prevents V
GATE(H)
and V
GATE(L)
from being in high state simul-
taneously.
11
PGnd
High current ground for the IC. The MOSFET drivers are referenced to
this pin. Input capacitor ground and the source of lower FET should be
tied to this pin.
12
V
GATE(L)
Low FET driver pin capable of 1.5A peak switching current.
13
V
CC1
Input power for the IC and low side gate driver.
14
LGnd
Signal ground for the IC. All control circuits are referenced to this pin.
15
COMP
Error amplifier compensation pin. A capacitor to ground should be
provided externally to compensate the amplifier.
16
V
FB
Error amplifier DC feedback input. This is the master voltage feedback
which sets the output voltage. This pin can be connected directly to the
output or a remote sense trace.
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