Cherry Semiconductor CS5151GD16, CS5151GN16, CS5151GDR16 Datasheet

The CS5151 is a 4-bit nonsyn­chronous N-Channel buck con­troller. It is designed to provide
unprecedented transient response
for today’s demanding high-densi­ty, high-speed logic. The regulator
operates using a proprietary control
method, which allows a 100ns
response time to load transients.
The CS5151 is designed to operate
over a 4.25-16V range (VCC) using
12V to power the IC and 5V as the
main supply for conversion.

The CS5151 is specifically designed
to power Pentium®processors with

MMX™ Technology and other high
performance core logic. It includes
the following features: on board,
4-bit DAC, short circuit protection,

1.0% output tolerance, VCCmonitor,
and programmable soft start capa­bility. The CS5151 is upwards com­patible with the 5-bit CS5156, allow­ing the mother board designer the
capability of using either the
CS5151 or the CS5156 with no
change in layout. The CS5151 is
available in 16 pin surface mount
and DIP packages.

Features

■ N-Channel Design

■ Excess of 1MHz Operation

■ 100ns Transient Response

■ 4-Bit DAC

■ Upward Compatible with

5-Bit CS5155/5156 and
Adjustable CS5120/5121

■ 30ns Gate Rise/Fall Times

■ 1% DAC Accuracy

■ 5V & 12V Operation

■ Remote Sense

■ Programmable Soft Start

■ Lossless Short Circuit

Protection

■ V

CC

Monitor

■ Adaptive Voltage

Positioning

■ V

2

™

Control Topology

■ Current Sharing

■ Overvoltage Protection

Package Options

CPU 4-Bit Nonsynchronous Buck Controller

CS5151

Description

Application Diagram

V

ID0

V

ID1

V

ID2

V

ID3

SS

NC

C

OFF

V

FFB

V

FB

COMP

LGnd

V

CC1

NC

PGnd
V

GATE

V

CC2

16 Lead SO Narrow & PDIP

1

Switching Power Supply for core logic - Pentium® processor with MMX™ Technology

0.33µF

V

ID0

V

ID1

V

ID2

V

ID3

V

ID0

V

ID1

V

ID2

V

ID3

V

CC1

SS

C

OFF

LGnd

V

FB

V

FFB

COMP

IRL3103

0.1µF

12V 5V

2µH

2.1V to 3.5V @ 13A

V

CC2

V

GATE

PGnd

1200µF/16V x 3
AlEl

3.3k

0.1µF

1200µF/16V x 5
AlEl

100pF

330pF

CS5151

MBR735

3

1,2

V2is a trademark of Switch Power, Inc.

Pentium is a registered trademark and MMX is a trademark of Intel Corporation.

CS5151

Cherry Semiconductor Corporation

2000 South County Trail, East Greenwich, RI 02818

Tel: [phone] Fax: [phone]

Email: [e-mail]

Web Site: www.cherry-semi.com

A Company

®

Rev. 1/5/99

1

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Electrical Characteristics:

0°C < TA< +70°C; 0°C < TJ< +85°C; 8V < V

CC1

< 14V; 5V < V

CC2

< 14V; DAC Code: V

ID2

= V

ID1

=

V

ID0

= 1; V

ID3

= 0; CV

GATE

= 1nF; C

OFF

= 330pF; CSS= 0.1µF, unless otherwise specified.

2

Pin Name Max Operating Voltage Max Current

V

CC1

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25mA DC/1.5A peak

V

CC2

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20mA DC/1.5A peak

SS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-100µA

COMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200µA

V

FB

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.2µA

C

OFF

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.2µA

V

FFB

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.2µA

V

ID0

- V

ID3

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-50µA

V

GATE

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16V/-0.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100mA DC/1.5A peak

LGnd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25mA

PGnd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100mA DC/1.5A peak

Operating Junction Temperature, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .°0 to 150°C

Lead Temperature Soldering

Wave Solder (through hole styles only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 sec. max, 260°C peak

Reflow (SMD styles only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60 sec. max above 183°C, 230°C peak

Storage Temperature Range, T

S

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-65° to 150°C

ESD Susceptibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2kV

CS5151

Absolute Maximum Ratings

■ Error Amplifier

VFBBias Current VFB= 0V 0.3 1.0 µA
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; VFB= 3V; VSS> 2V 0.4 2.5 8.0 mA

COMP SOURCE Current V

COMP

= 1.2V; VFB= 2.7V; VSS= 5V 30 50 70 µA

COMP CLAMP Current V

COMP

= 0V; VFB= 2.7V 0.4 1.0 1.6 mA
COMP High Voltage VFB= 2.7V; VSS= 5V 4.0 4.3 5.0 V
COMP Low Voltage VFB=3V 160 600 mV
PSRR 8V < V

CC1

< 14V @ 1kHz; Note 1 60 85 dB

■ 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

■ DAC

Input Threshold V

ID0

, V

ID1

, V

ID2

, V

ID3

1.00 1.25 2.40 V

Input Pull Up Resistance V

ID0

, V

ID1

, V

ID2

, V

ID3

25 50 100 kΩ
Pull Up Voltage 4.85 5.00 5.15 V
Accuracy Measure VFB= V

COMP

, 25°C ≤ TJ≤ 85°C 1.0 %

V

ID3VID2

V

ID1

V

ID0

1 1 1 1 1.2315 1.2440 1.2564 V
1 1 1 0 2.1186 2.1400 2.1614 V
1 1 0 1 2.2176 2.2400 2.2624 V
1 1 0 0 2.3166 2.3400 2.3634 V
1 0 1 1 2.4156 2.4400 2.4644 V
1 0 1 0 2.5146 2.5400 2.5654 V
1 0 0 1 2.6136 2.6400 2.6664 V
1 0 0 0 2.7126 2.7400 2.7674 V
0 1 1 1 2.8116 2.8400 2.8684 V
0 1 1 0 2.9106 2.9400 2.9694 V
0 1 0 1 3.0096 3.0400 3.0704 V

CS5151

3

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Electrical Characteristics:

0°C < TA< +70°C; 0°C < TJ< +85°C; 8V < V

CC1

< 14V; 5V < V

CC2

< 14V; DAC Code: V

ID2

= V

ID1

=

V

ID0

= 1; V

ID3

= 0; CV

GATE

= 1nF; C

OFF

= 330pF; CSS= 0.1µF, unless otherwise specified.

■ DAC: continued

V

ID3

V

ID2

V

ID1

V

ID0

0 1 0 0 3.1086 3.1400 3.1714 V
0 0 1 1 3.2076 3.2400 3.2724 V
0 0 1 0 3.3066 3.3400 3.3734 V
0 0 0 1 3.4056 3.4400 3.4744 V
0 0 0 0 3.5046 3.5400 3.5754 V

■ V

GATE

Out SOURCE Sat at 100mA Measure V

CC2

– V

GATE

1.2 2.0 V

Out SINK Sat at 100mA Measure V

GATE

– VPGnd; 1.0 1.5 V

Out Rise Time 1V < V

GATE

< 9V; V

CC1

= V

CC2

= 12V 30 50 ns

Out Fall Time 9V > V

GATE

> 1V; V

CC1

= V

CC2

= 12V 30 50 ns
Shoot-Through Current Note 1 50 mA
V

GATE

Resistance Resistor to LGnd 20 50 100 kΩ

V

GATE

Schottky LGnd to V

GATE

@ 10mA 600 800 mV

■ 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 VFB= 0V; VSS= 0 0.50 0.95 1.10 V
V

FFB

SS Fault Disable V

GATE

= Low 0.9 1.0 1.1 V

High Threshold 2.5 3.0 V

■ PWM Comparator

Transient Response V

FFB

= 0 to 5V to V

GATE

= 9V to 1V; 100 125 ns

V

CC1

= V

CC2

= 12V

V

FFB

Bias Current V

FFB

= 0V 0.3 µA

■ Supply Current

I

CC1

No Switching 8.5 13.5 mA

I

CC2

No Switching 1.6 3.0 mA

Operating I

CC1

VFB= COMP = V

FFB

813mA

Operating I

CC2

VFB= COMP = V

FFB

25 mA

■ C

OFF

Normal Charge Time V

FFB

= 1.5V; VSS= 5V 1.0 1.6 2.2 µs

Extension Charge Time VSS= V

FFB

= 0 5.0 8.0 11.0 µs

Discharge Current C

OFF

to 5V; V

FB

>1V 5.0 mA

■ Time Out Timer

Time Out Time VFB= V

COMP

; V

FFB

= 2V; 10 30 50 µs

Record V

GATE

Pulse High Duration

Fault Mode Duty Cycle V

FFB

= 0V 35 50 65 %

Note 1: Guaranteed by design, not 100% tested in production.

4

CS5151

Package Pin Description

PACKAGE PIN # PIN SYMBOL FUNCTION

16L SO Narrow & PDIP

1,2,3,4 V

ID0

– V

ID3

Voltage ID DAC input pins. These pins are internally pulled up to 5V
providing logic ones if left open. The DAC range is 2.14V to 3.54V with
100mV increments. V

ID0

- V

ID3

select the desired DAC output voltage.

Leaving all 4 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 60µA current source provides soft start function for the con­troller. This pin disables fault detect function during Soft Start. When a
fault is detected, the soft start capacitor is slowly discharged by internal
2µA 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.

6, 12 NC No connection.

7C

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.

8V

FFB

Fast feedback connection to the PWM comparator. This pin is connected
to the regulator output. The inner feedback loop terminates on time.

9V

CC2

Boosted power for the gate driver.

10 V

GATE

MOSFET driver pin capable of 1.5A peak switching current.

11 PGnd High current ground for the IC. The MOSFET driver is referenced to this

pin. Input capacitor ground and the anode of the Schottky diode should
be tied to this pin.

13 V

CC1

Input power for the IC.

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 pro-

vided 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.

5

CS5151

Block Diagram

V

Applications Information

V

2

™

Control Method

The V

2

™

method of control uses a ramp signal that is gen­erated by the ESR of the output capacitors. This ramp is
proportional to the AC current through the main inductor
and is offset by the value of the DC output voltage. This
control scheme inherently compensates for variation in
either line or load conditions, since the ramp signal is gen­erated from the output voltage itself. This control scheme
differs from traditional techniques such as voltage mode,
which generates an artificial ramp, and current mode,
which generates a ramp from inductor current.

Figure 1: V

2

™

Control Diagram

The V

2

™

control method is illustrated in Figure 1. The out­put voltage is used to generate both the error signal and the
ramp signal. Since the ramp signal is simply the output
voltage, it is affected by any change in the output regard­less of the origin of that change. The ramp signal also con­tains the DC portion of the output voltage, which allows
the control circuit to drive the main switch to 0% or 100%
duty cycle as required.

A change in line voltage changes the current ramp in the
inductor, affecting the ramp signal, which causes the V

2

™

control scheme to compensate the duty cycle. Since the
change in inductor current modifies the ramp signal, as in
current mode control, the V

2

™

control scheme has the

same advantages in line transient response.
A change in load current will have an affect on the output

voltage, altering the ramp signal. A load step immediately
changes the state of the comparator output, which controls
the main switch. Load transient response is determined
only by the comparator response time and the transition
speed of the main switch. The reaction time to an output
load step has no relation to the crossover frequency of the
error signal loop, as in traditional control methods.

The error signal loop can have a low crossover frequency,
since transient response is handled by the ramp signal loop.
The main purpose of this ‘slow’ feedback loop is to provide
DC accuracy. Noise immunity is significantly improved,
since the error amplifier bandwidth can be rolled off at a low
frequency. Enhanced noise immunity improves remote sens-

Theory of Operation

CC1

SS

V

ID0

V

ID1

V

ID2

V

ID3

V

COMP

V

FFB

LGnd

V

V

Monitor

CC1

Comparator

-

60µA

2µA

-

+

-

+

V

FFB

Comparator

5V

2.5V

Low

+

3.90V

3.85V

4 BIT

DAC

FB

Slow Feedback

Fast Feedback

+

-

Error
Amplifier

PWM
Comparator

1V

0.7V

-

+

+

-

Maximum

On-Time

Timeout

Normal

Off-Time

Timeout

Extended

Off-Time

Timeout

SS Low
Comparator

SS High
Comparator

R

S

FAULT

Latch

Off-Time

Timeout

FAULT

Q

FAULT

Q

R

Q

S

Q

PWM
Latch

GATE = ON

GATE = OFF

C

OFF

One Shot

R

S

Q

CC2

V

GATE

PGnd

C

OFF

PWM
COMP

COMP

PWM
Comparator

+

C

–

Ramp
Signal

Error

Signal

Error

Amplifier

V

V

GATE

FFB

E

Output
Voltage
Feedback

V

FB

–

+

Reference

Voltage

Time Out

Timer

(30µs)

Edge Triggered