Renesas ISL8036IRZ-T Dual 3a 1mhz/2.5mhz high efficiency synchronous buck regulator Datasheet

DATASHEET
ISL8036, ISL8036A
FN6853
Rev 3.00
August 17, 2012
Dual 3A 1MHz/2.5MHz High Efficiency Synchronous Buck Regulator
ISL8036, ISL8036A are integrated power controllers rated for
dual 3A output current or current sharing operation with a
1MHz (ISL8036)/2.5MHz (ISL8036A) step-down regulator,
which is ideal for any low power low-voltage applications. The
channels are 180° out-of-phase for input RMS current and EMI
reduction. It is optimized for generating low output voltages
down to 0.8V each. The supply voltage range is from 2.8V to
6V, allowing for the use of a single Li+ cell, three NiMH cells or
a regulated 5V input. The two channels are 180° out-of-phase,
and each one has a guaranteed minimum output current of
3A. They can be combined to form a single 6A output in the
current sharing mode. While in current sharing, the interleaved
PWM signals reduce input and output ripple.
Features
The ISL8036, ISL8036A includes a pair of low ON-resistance
P-channel and N-channel internal MOSFETs to maximize
efficiency and minimize external component count. 100%
duty-cycle operation allows less than 250mV dropout voltage
at 3A each.
• Reverse Overcurrent Protection
The ISL8036, ISL8036A offers an independent 1ms
Power-good (PG) timer at power-up. When shutdown, ISL8036,
ISL8036A discharges the output capacitor. Other features
include internal digital soft-start, enable for power sequence,
overcurrent protection, and thermal shutdown.
• Plug-in DC/DC Modules for Routers and Switchers
The ISL8036, ISL8036A is offered in a 24 Ld 4mmx4mm QFN
package with 1mm maximum height. The complete converter
occupies less than 1.5cm2 area.
• 3A High Efficiency Synchronous Buck Regulator with up to
95% Efficiency
• 2% Output Accuracy Over-Temperature/Load/Line
• Internal Digital Soft-Start - 1.5ms
• 6A Current Sharing Mode Operation
• External Synchronization up to 6MHz
• Internal Current Mode Compensation
• Peak Current Limiting and Hiccup Mode Short Circuit
Protection
Applications
• DC/DC POL Modules
• µC/µP, FPGA and DSP Power
• Test and Measurement Systems
• Li-ion Battery Power Devices
• Bar Code Reader
Related Literature
• AN1616, “ISL8036CRSHEVAL1Z Current Sharing 6A Low
Quiescent Current High Efficiency Synchronous Buck
Regulator”
• AN1617, “ISL8036DUALEVAL1Z Dual 3A Low Quiescent
Current High Efficiency Synchronous Buck Regulator”
• AN1615, “ISL8036ACRSHEVAL1Z Current Sharing 6A Low
Quiescent Current High Efficiency Synchronous Buck
Regulator”
• AN1618, “ISL8036ADUALEVAL1Z Dual 3A Low Quiescent
Current High Efficiency Synchronous Buck Regulator”
100
EFFICIENCY (%)
90
80
3.3VOUT- PWM
70
60
50
40
0
1
2
3
4
OUTPUT LOAD (A)
5
6
FIGURE 1. EFFICIENCY vs LOAD, 1MHz 5VIN PWM, TA = +25°C
FN6853 Rev 3.00
August 17, 2012
Page 1 of 26
ISL8036, ISL8036A
Typical Applications
L1
1.5µH
INPUT 2.8V TO 6V
VIN1, 2
LX1
C2
2x22µF
VDD
C1
2x22µF
EN1
EN2
OUTPUT1
1.8V/6A
PGND
ISL8036,
ISL8036A
R2
124k
C3
12pF
FB1
R3
100k
PG1
SGND
L2
1.5µH
SYNC
LX2
PG2
C4
2x22µF
SS
PGND
C5
22nF
FB2
COMP
C6
150pF
R6
50k
SGND
FIGURE 2. TYPICAL APPLICATION DIAGRAM - SINGLE 6A
L1
1.5µH
INPUT 2.7V TO 6V
VIN
C1
2x22µF
LX1
C2
2x22µF
VDD
SS
EN1
OUTPUT1
1.8V/3A
PGND
ISL8036,
ISL8036A
R2
124k
C3
12pF
FB1
R3
100k
PG1
SGND
L2
1.5µH
SYN C
OUTPUT2
1.8V/3A
LX2
C4
2x22µF
EN2
PGND
PG2
R5
124k
C5
12pF
FB2
R6
100k
COMP
SGND
FIGURE 3. TYPICAL APPLICATION DIAGRAM - DUAL 3A OUTPUTS
FN6853 Rev 3.00
August 17, 2012
Page 2 of 26
ISL8036, ISL8036A
TABLE 1. COMPONENT VALUE SELECTION FOR DUAL OPERATION
VOUT
0.8V
1.2V
1.5V
1.8V
2.5V
3.3V
C1
2x22µF
2x22µF
2x22µF
2x22µF
2x22µF
2x22µF
C2 (or C4)
2X22µF
2X22µF
2X22µF
2X22µF
2X22µF
2X22µF
L1 (or L2)*
1.0~2.2µH
1.0~2.2µH
1.0~2.2µH
1.0~3.3µH
1.0~3.3µH
1.0~4.7µH
R2 (or R5)
0
50k
87.5k
124k
212.5k
312.5k
R3 (or R6)
100k
100k
100k
100k
100k
100k
*For ISL8036A, the values used for L1 (or L2) are half the values specified above for each VOUT.
TABLE 2. COMPONENT VALUE SELECTION FOR CURRENT SHARING OPERATION
VOUT
0.8V
1.2V
1.5V
1.8V
2.5V
3.3V
C1
2x22µF
2x22µF
2x22µF
2x22µF
2x22µF
2x22µF
C2 (or C4)
2X22µF
2X22µF
2X22µF
2X22µF
2X22µF
2X22µF
L1 (or L2)*
1.0~2.2µH
1.0~2.2µH
1.0~2.2µH
1.0~3.3µH
1.0~3.3µH
1.0~4.7µH
R2
0
50k
87.5k
124k
212.5k
312.5k
R3
100k
100k
100k
100k
100k
100k
R6
30k
33k
31k
30k
29k
28k
C6
250pF
180pF
150pF
150pF
150pF
150pF
*For ISL8036A, the values used for L1 (or L2) are half the values specified above for each VOUT.
NOTE: C5 value (22nF) is given by Equation 1 corresponding to the desired soft-start time.
TABLE 3. SUMMARY OF DIFFERENCES
PART NUMBER
ISL8036
ISL8036A
FN6853 Rev 3.00
August 17, 2012
SWITCHING FREQUENCY
Internally fixed switching frequency FSW = 1MHz
Internally fixed switching frequency FSW = 2.5MHz
Page 3 of 26
ISL8036, ISL8036A
Block Diagram
COMP
27p F
EN1
SO FTSTAR
START
T
SHUTDO W N
BANDGAP
0.8V
0.3p F
390k
SHUTDOW N
V IN 1
+
SS
PW M
L O G IC
CO NTRO LLER
P R O T E C T IO N
D R IV E R
+
COMP
EAMP
LX1
3p F
PG ND
SLOPE
COMP
+
+
FB1
CSA1
1.6 k
0.5V
0.864V
SCP
+
+
+
V IN 1
O S C IL L A T O R
0.736V
1M
PG1
SYNC
1m s
DELAY
SGND
SHUTDO W N
THERM AL
SHUTDO W N
27 p F
39 0k
SS
SO FTSTAR
START
T
SHUTDO W N
0.3p F
SHUTDO W N
V IN 2
BANDGAP
0.8V
+
EN2
OCP
THRESHO LD
L O G IC
+
COMP
EAM P
3p F
PW M
L O G IC
CO NTRO LLER
P R O T E C T IO N
D R IV E R
LX2
PG ND
SLO PE
COMP
+
+
FB2
CSA2
1.6k
0.5V
0.864V
SCP
+
+
+
V IN 2
0.736V
1M
PG2
1m s
DELAY
SGND
FN6853 Rev 3.00
August 17, 2012
Page 4 of 26
ISL8036, ISL8036A
Pin Configuration
LX2
PGND2
PGND2
PGND1
PGND1
LX1
ISL8036, ISL8036A
(24 LD QFN)
TOP VIEW
24
23
22
21
20
19
LX2
1
18 LX1
VIN2
2
17 VIN1
VIN2
3
EN2
4
PG2
5
14 SS
FB2
6
13 EN1
16 VIN1
25
PAD
8
9
10
11
NC
FB1
SGND
PG1
12
SYNC
7
COMP
15 VDD
Pin Descriptions
PIN
NUMBER
SYMBOL
1, 24
LX2
22, 23
PGND2
4
EN2
Regulator Channel 2 enable pin. Enable the output, VOUT2, when driven to high. Shutdown the VOUT2 and discharge
output capacitor when driven to low. Do not leave this pin floating.
5
PG2
1ms timer output. At power-up or EN HI, this output is a 1ms delayed Power-Good signal for the VOUT2 voltage.
6
FB2
The feedback network of the Channel 2 regulator. To be connected to FB1 (current sharing)
7
COMP
8
NC
No connect pin; please tie to GND.
9
FB1
The feedback network of the Channel 1 regulator. FB1 is the negative input to the transconductance error amplifier.
The output voltage is set by an external resistor divider connected to FB1. With a properly selected divider, the output
voltage can be set to any voltage between the power rail (reduced by converter losses) and the 0.8V reference. There
is an internal compensation to meet a typical application. In addition, the regulator power-good and undervoltage
protection circuitry use FB1 to monitor the Channel 1 regulator output voltage.
10
SGND
11
PG1
1ms timer output. At power-up or EN HI, this output is a 1ms delayed Power-Good signal for the VOUT1 voltage.
12
SYNC
Connect to logic high or input voltage VIN . Connect to an external function generator for external Synchronization.
Negative edge trigger. Do not leave this pin floating. Do not tie this pin low (or to SGND).
13
EN1
Regulator Channel 1 enable pin. Enable the output, VOUT1, when driven to high. Shutdown the VOUT1 and discharge
output capacitor when driven to low. Do not leave this pin floating.
FN6853 Rev 3.00
August 17, 2012
DESCRIPTION
Switching node connection for Channel 2. Connect to one terminal of inductor for VOUT2.
Negative supply for the power stage of Channel 2.
An additional external network across COMP and SGND is required to improve the loop compensation of the amplifier
channel parallel operation. The soft-start pin should be tied to the external capacitor. COMP pin is NC in dual mode
operation, using internal compensation. If SS pin is tied to CSS (without connection to VIN), external compensation is
automtaically used. Connect an external R,C network on COMP pin for parallel mode operation.
System ground.
Page 5 of 26
ISL8036, ISL8036A
Pin Descriptions (Continued)
PIN
NUMBER
SYMBOL
DESCRIPTION
14
SS
SS is used to adjust the soft-start time. When SS pin is tied to VIN, SS time is 1.5ms. SS pin is tied to VIN only in dual
mode operation. SS pin is tied to CSS only in parallel mode operation, using only external compensation. Connect a
capacitor from SS to SGND to adjust the soft-start time (current sharing). CSS should not be larger than 33nF. This
capacitor, along with an internal 5µA current source sets the soft-start interval of the converter, tSS.
(EQ. 1)
C SS  F  = 6.25  t SS  s 
15
VDD
Input supply voltage for the logic. VDD to be at the same potential as VIN +0.3/-0.5V.
20, 21
PGND1
18, 19
LX1
16, 17
2, 3
VIN1,
VIN2
Input supply voltage. Connect 22µF ceramic capacitor to power ground per channel.
25
PAD
The exposed pad must be connected to the SGND pin for proper electrical performance. Add as much vias as possible
for optimal thermal performance.
Negative supply for the power stage of Channel 1.
Switching node connection for Channel 1. Connect to one terminal of inductor for VOUT1.
Ordering Information
PART NUMBER
(Notes 2, 3)
PART
MARKING
TEMP. RANGE
(°C)
PACKAGE
(Pb-free)
PKG.
DWG. #
ISL8036IRZ
80 36IRZ
-40 to +85
24 Ld 4x4 QFN
L24.4x4D
ISL8036IRZ-T (Note 1)
80 36IRZ
-40 to +85
24 Ld 4x4 QFN
L24.4x4D
ISL8036AIRZ
80 36AIRZ
-40 to +85
24 Ld 4x4 QFN
L24.4x4D
ISL8036AIRZ-T (Note 1)
80 36AIRZ
-40 to +85
24 Ld 4x4 QFN
L24.4x4D
ISL8036CRSHEVAL1Z
Evaluation Board
ISL8036DUALEVAL1Z
Evaluation Board
ISL8036ACRSHEVAL1Z
Evaluation Board
ISL8036ADUALEVAL1Z
Evaluation Board
NOTES:
1. Please refer to TB347 for details on reel specifications.
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte tin plate plus
anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil Pb-free products are MSL
classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
3. For Moisture Sensitivity Level (MSL), please see device information page for ISL8036, ISL8036A. For more information on MSL, please see Technical
Brief TB363.
FN6853 Rev 3.00
August 17, 2012
Page 6 of 26
ISL8036, ISL8036A
Table of Contents
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Thermal Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Electrical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
ISL8036 Typical Operating Performance for Dual PWM Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
ISL8036A Typical Operating Performance for Dual PWM Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
ISL8036 Typical Operating Performance for Current Sharing PWM Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
ISL8036A Typical Operating Performance for Current Sharing PWM Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Theory of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
PWM Control Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Synchronization Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Current Sharing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overcurrent Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
UVLO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Soft-start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Discharge Mode (Soft-Stop) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power MOSFETs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
100% Duty Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermal Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22
22
22
22
22
23
23
23
23
23
23
23
Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Output Inductor and Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Voltage Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PCB Layout Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23
23
23
24
Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Package Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
FN6853 Rev 3.00
August 17, 2012
Page 7 of 26
ISL8036, ISL8036A
Absolute Maximum Ratings
Thermal Information
(Reference to SGND)
VIN1, VIN2, VDD . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.5V (DC) or 7V (20ms)
LX1, LX2 . . . . . . . . . . . . . -3V/(10ns)/-1.5V (100ns)/-0.3V (DC) to 6.5V (DC) or
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V (20ms)/8.5V(10ns)
EN1, EN2, PG1, PG2, SYNC, SS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +6.5V
FB1, FB2, COMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 2.7V
NC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 0.3V
ESD Ratings
Human Body Model (Tested per JESD22-A114) . . . . . . . . . . . . . . . . . 4kV
Charged Device Model (Tested per JESD22-C101E). . . . . . . . . . . . . . 2kV
Machine Model (Tested per JESD22-A115). . . . . . . . . . . . . . . . . . . . 300V
Latch Up (Tested per JESD-78A; Class 2, Level A) . . . . . . . . . . . . . . 100mA
Thermal Resistance (Typical)
JA (°C/W) JC (°C/W)
24 Ld 4x4 QFN (Notes 4, 5). . . . . . . . . . .
36
2
Junction Temperature Range . . . . . . . . . . . . . . . . . . . . . . .-55°C to +150°C
Storage Temperature Range. . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C
Ambient Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
Recommended Operating Conditions
VIN Supply Voltage Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.85V to 6V
Load Current Range per Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . 0A to 3A
Ambient Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product
reliability and result in failures not covered by warranty.
NOTES:
4. JA is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See Tech
Brief TB379.
5. For JC, “case temperature” location is at the center of the exposed metal pad on the package underside.
Electrical Specifications Unless otherwise noted, the typical specifications are measured at the following conditions:
TA = -40°C to +85°C, VIN = 3.6V, EN1 = EN2 = VDD, L = 1.5µH, C1 = C2 = C4 = 2x22µF, IOUT1 = IOUT2 = 0A to 3A, unless otherwise noted. Typical values
are at TA = +25°C. Boldface limits apply over the operating temperature range, -40°C to +85°C.
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
(Note 6)
TYP
MAX
(Note 6)
2.5
2.85
50
100
UNITS
INPUT SUPPLY
VIN Undervoltage Lockout Threshold
VUVLO
Rising
Hysteresis
Quiescent Supply Current
IVDD
Shutdown Supply Current
ISD
SYNC = VDD, EN1 = EN2 = VDD,
FS = 1MHz, no load at the output
15
FS = 2.5MHz, no load at the output
VDD = 6V, EN1 = EN2 = SGND
V
mV
40
mA
30
70
mA
8
20
µA
0.8
0.810
OUTPUT REGULATION
FB1, FB2 Regulation Voltage
VFB
FB1, FB2 Bias Current
IFB
0.790
VFB = 0.75V
Load Regulation
SYNC = VDD, output load from 0A to 6A
Line Regulation
VIN = VO + 0.5V to 6V (minimal 2.85V)
Soft-start Ramp Time Cycle
Soft-start Charging Current
SS = VDD
ISS
µA
2
mV/A
0.1
%/V
1.5
4
V
0.1
5
ms
6
µA
COMPENSATION
Error Amplifier Trans-Conductance
SS = VDD
20
SS with Capacitor
Trans-resistance
Trans-resistance Matching
µA/V
100
RT
0.180
RT_match
-0.03
0.2
µA/V
0.220
Ω
+0.03
Ω
OVERCURRENT PROTECTION
Dynamic Current Limit ON-time
tOCON
Dynamic Current Limit OFF-time
tOCOFF
Positive Peak Overcurrent Limit
Ipoc1
Ipoc2
4.1
4.8
5.5
A
Negative Peak Overcurrent Limit
Inoc1
-3.5
-2.5
-1.5
A
Inoc2
-3.5
-2.5
-1.5
A
FN6853 Rev 3.00
August 17, 2012
17
Clock pulses
8
4.1
4.8
SS cycle
5.5
A
Page 8 of 26
ISL8036, ISL8036A
Electrical Specifications Unless otherwise noted, the typical specifications are measured at the following conditions:
TA = -40°C to +85°C, VIN = 3.6V, EN1 = EN2 = VDD, L = 1.5µH, C1 = C2 = C4 = 2x22µF, IOUT1 = IOUT2 = 0A to 3A, unless otherwise noted. Typical values
are at TA = +25°C. Boldface limits apply over the operating temperature range, -40°C to +85°C. (Continued)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
(Note 6)
TYP
MAX
(Note 6)
UNITS
LX1, LX2
P-Channel MOSFET ON-Resistance
N-Channel MOSFET ON-Resistance
VIN = 6V, IO = 200mA
50
75
mΩ
VIN = 2.7V, IO = 200mA
70
100
mΩ
VIN = 6V, IO = 200mA
50
75
mΩ
VIN = 2.7V, IO = 200mA
70
100
mΩ
MHz
LX_ Maximum Duty Cycle
PWM Switching Frequency
Synchronization Frequency Range
100
FS
FSYNC
Channel 1 to Channel 2 Phase Shift
Soft Discharge Resistance
0.88
1.1
1.32
ISL8036A
2.15
2.5
2.85
MHz
ISL8036 (Note 7)
2.64
6
MHz
Rising edge to rising edge timing
LX Minimum On Time
180
SYNC = High (PWM mode)
RDIS
LX Leakage Current
%
ISL8036
EN = LOW
80
Pulled up to 6V
°
140
ns
100
120
Ω
0.1
1
µA
PG1, PG2
Output Low Voltage
Sinking 1mA, VFB = 0.7V
PG Pin Leakage Current
PG = VIN = 6V
0.3
V
0.01
0.1
µA
Internal PGOOD Low Rising Threshold
Percentage of nominal regulation voltage
89.5
92
94.5
%
Internal PGOOD Low Falling Threshold
Percentage of nominal regulation voltage
85
88
91
%
Delay Time (Rising Edge)
Time from VOUT_ reached regulation
1
Internal PGOOD Delay Time
(Falling Edge)
7
ms
10
µs
0.4
V
0.1
1
µA
0.1
1
µA
EN1, EN2, SYNC
Logic Input Low
Logic Input High
1.5
SYNC Logic Input Leakage Current
ISYNC
Pulled up to 6V
Enable Logic Input Leakage Current
IEN
Pulled up to 6V
V
Thermal Shutdown
150
°C
Thermal Shutdown Hysteresis
25
°C
NOTES:
6. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization and
are not production tested.
7. The operational frequency per switching channel will be half of the SYNC frequency.
FN6853 Rev 3.00
August 17, 2012
Page 9 of 26
ISL8036, ISL8036A
ISL8036 Typical Operating Performance for Dual PWM Operation
100
100
90
90
1.8VOUT
80
2.5VOUT
1.2VOUT
70
EFFICIENCY (%)
EFFICIENCY (%)
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, FSW = 1MHz.
1.5VOUT
60
1.8VOUT
80
1.5VOUT
1.2VOUT
3.3VOUT
70
60
50
50
40
0.0
0.5
1.0
1.5
IOUT (A)
2.0
2.5
40
0.0
3.0
FIGURE 4. EFFICIENCY, VIN = 3.3V, TA = +25°C
1.0
1.805
OUTPUT VOLTAGE (V)
1.810
3.3VIN
0.6
5VIN
0.4
0.2
0
0.0
0.5
1.0
1.5
IOUT (A)
2.0
2.5
0.5
1.0
1.5
IOUT (A)
2.0
2.5
3.0
FIGURE 5. EFFICIENCY, VIN = 5V, TA = +25°C
1.2
0.8
PD (W)
2.5VOUT
3.0
FIGURE 6. POWER DISSIPATION, VOUT = 1.8V, TA = +25°C
1.800
1.795
5VIN
1.790
2.7VIN
1.785
1.780
0
0.5
3.3VIN
1.0
1.5
2.0
OUTPUT LOAD (A)
2.5
3.0
FIGURE 7. VOUT REGULATION vs LOAD, 1.8V, TA = +25°C
1.810
LX1 2V/DIV
OUTPUT VOLTAGE (V)
1.805
1.800
1.795
VOUT RIPPLE 20mV/DIV
1.790
1.785
3A LOAD
1.780
2.5
3.0
2A LOAD
3.5
4.0
0A LOAD
4.5
IL1 0.5A/DIV
5.0
5.5
INPUT VOLTAGE (V)
FIGURE 8. OUTPUT VOLTAGE REGULATION vs VIN, 1.8V, TA = +25°C
FN6853 Rev 3.00
August 17, 2012
FIGURE 9. STEADY STATE OPERATION AT NO LOAD CHANNEL 1
Page 10 of 26
ISL8036, ISL8036A
ISL8036 Typical Operating Performance for Dual PWM Operation
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, FSW = 1MHz. (Continued)
LX2 2V/DIV
LX1 2V/DIV
VOUT RIPPLE 20mV/DIV
VOUT2 RIPPLE 20mV/DIV
IL1 2A/DIV
IL2 0.5A/DIV
FIGURE 10. STEADY STATE OPERATION AT NO LOAD CHANNEL 2
FIGURE 11. STEADY STATE OPERATION WITH FULL LOAD CHANNEL 1
LX2 2V/DIV
VOUT RIPPLE 50mV/DIV
IL1 2A/DIV
VOUT RIPPLE 20mV/DIV
IL2 2A/DIV
FIGURE 12. STEADY STATE OPERATION WITH FULL LOAD CHANNEL 2
FIGURE 13. LOAD TRANSIENT CHANNEL 1
EN1 2V/DIV
VOUT2 RIPPLE 20mV/DIV
VOUT 1V/DIV
IL1 0.5A/DIV
IL2 2A/DIV
PG1 5V/DIV
FIGURE 14. LOAD TRANSIENT CHANNEL 2
FN6853 Rev 3.00
August 17, 2012
FIGURE 15. SOFT-START WITH NO LOAD CHANNEL 1
Page 11 of 26
ISL8036, ISL8036A
ISL8036 Typical Operating Performance for Dual PWM Operation
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, FSW = 1MHz. (Continued)
EN2 2V/DIV
EN1 2V/DIV
VOUT1 1V/DIV
VOUT2 0.5V/DIV
IL1 2A/DIV
IL2 0.5A/DIV
PG2 5V/DIV
FIGURE 16. SOFT-START WITH NO LOAD CHANNEL 2
PG1 5V/DIV
FIGURE 17. SOFT-START AT FULL LOAD CHANNEL 1
EN1 5V/DIV
EN2 2V/DIV
VOUT2 0.5V/DIV
IL2 2A/DIV
VOUT1 0.5V/DIV
IL1 0.5A/DIV
PG2 5V/DIV
PG1 5V/DIV
FIGURE 18. SOFT-START AT FULL LOAD CHANNEL 2
FIGURE 19. SOFT-DISCHARGE SHUTDOWN CHANNEL 1
LX1 2V/DIV
EN2 2V/DIV
SYNCH 5V/DIV
VOUT2 0.5V/DIV
IL2 0.5A/DIV
VOUT1 RIPPLE 20mV/DIV
PG2 5V/DIV
FIGURE 20. SOFT-DISCHARGE SHUTDOWN CHANNEL 2
FN6853 Rev 3.00
August 17, 2012
IL1 1A/DIV
FIGURE 21. STEADY STATE OPERATION CHANNEL 1 AT NO LOAD
WITH FSW = 2.4MHz
Page 12 of 26
ISL8036, ISL8036A
ISL8036 Typical Operating Performance for Dual PWM Operation
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, FSW = 1MHz. (Continued)
SYNCH 5V/DIV
LX2 2V/DIV
LX1 2V/DIV
SYNCH 5V/DIV
VOUT1 RIPPLE 20mV/DIV
VOUT2 RIPPLE 20mV/DIV
IL1 2A/DIV
IL2 1A/DIV
FIGURE 22. STEADY STATE OPERATION CHANNEL 2 AT NO LOAD
WITH FSW = 2.4MHz
FIGURE 23. STEADY STATE OPERATION CHANNEL 1 AT FULL LOAD
WITH FSW = 2.4MHz
LX2 2V/DIV
LX1 2V/DIV
SYNCH 5V/DIV
SYNCH 5V/DIV
VOUT2 RIPPLE 20mV/DIV
VOUT1 RIPPLE 20mV/DIV
IL2 2A/DIV
IL1 2A/DIV
FIGURE 24. STEADY STATE OPERATION CHANNEL 2 AT FULL LOAD
WITH FSW = 2.4MHz
FIGURE 25. STEADY STATE OPERATION CHANNEL 1 AT NO LOAD
WITH FSW = 6MHz
LX2 2V/DIV
PHASE1 5V/DIV
SYNCH 5V/DIV
VOUT1 1V/DIV
VOUT2 RIPPLE 20mV/DIV
IL2 2A/DIV
FIGURE 26. STEADY STATE OPERATION CHANNEL 2 AT NO LOAD
WITH FSW = 5MHz
FN6853 Rev 3.00
August 17, 2012
IL1 1A/DIV
PG1 5V/DIV
FIGURE 27. OUTPUT SHORT CIRCUIT CHANNEL 1
Page 13 of 26
ISL8036, ISL8036A
ISL8036 Typical Operating Performance for Dual PWM Operation
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, FSW = 1MHz. (Continued)
PHASE1 5V/DIV
PHASE2 5V/DIV
VOUT1 1V/DIV
IL1 1A/DIV
VOUT2 0.5V/DIV
PG2 5V/DIV
PG1 5V/DIV
FIGURE 28. OUTPUT SHORT CIRCUIT RECOVERY (FROM HICCUP)
CHANNEL 1
IL2 1A/DIV
FIGURE 29. OUTPUT SHORT CIRCUIT CHANNEL 2
PHASE2 5V/DIV
VOUT2 1V/DIV
IL2 1A/DIV
PG2 5V/DIV
FIGURE 30. OUTPUT SHORT CIRCUIT RECOVERY (FROM HICCUP) CHANNEL 2
FN6853 Rev 3.00
August 17, 2012
Page 14 of 26
ISL8036, ISL8036A
ISL8036A Typical Operating Performance for Dual PWM Operation
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, L1 = L2 = 0.6µH,
FSW = 2.5MHz.
100
100
2.5VOUT
2.5VOUT
90
80
1.2VOUT
1.5VOUT
70
EFFICIENCY (%)
EFFICIENCY (%)
90
1.8VOUT
60
80
1.5VOUT
1.2VOUT
70
1.8VOUT
60
50
50
40
0.0
0.5
1.0
1.5
2.0
2.5
40
0.0
3.0
0.5
OUTPUT LOAD (A)
1.0
1.5
2.0
OUTPUT LOAD (A)
2.5
3.0
FIGURE 32. EFFICIENCY vs LOAD, 5VIN DUAL CHANNEL 1,
TA = +25°C
FIGURE 31. EFFICIENCY vs LOAD, 3.3VIN DUAL CHANNEL 1,
TA = +25°C
1.50
1.810
1.25
1.805
OUTPUT VOLTAGE (V)
POWER DISSIPATION (W)
3.3VOUT
1.00
0.75
2.7VIN
0.50
3.3VIN
0.25
1.800
1.795
1.790
5VIN
3.3VIN
2.7VIN
1.785
5VIN
0.00
0
0.5
1.0
1.5
2.0
2.5
3.0
1.780
0
0.5
1.0
1.5
2.0
2.5
3.0
OUTPUT LOAD (A)
OUTPUT LOAD (A)
FIGURE 33. POWER DISSIPATION vs LOAD, 1.8VOUT DUAL CHANNEL 1,
TA = +25°C
FIGURE 34. VOUT REGULATION vs LOAD, 1.8VOUT DUAL CHANNEL 1,
TA = +25°C
1.810
LX1 2V/DIV
OUTPUT VOLTAGE (V)
1.805
1.800
1.795
1.790
VOUT RIPPLE 20mV/DIV
3A LOAD
1.785
1.780
2.5
3.0
1.5A LOAD
3.5
4.0
IL1 0.5A/DIV
0A LOAD
4.5
5.0
5.5
INPUT VOLTAGE (V)
FIGURE 35. VOUT REGULATION vs VIN, 1.8VOUT DUAL CHANNEL 1,
TA = +25°C
FN6853 Rev 3.00
August 17, 2012
FIGURE 36. STEADY STATE OPERATION AT NO LOAD CHANNEL 1
Page 15 of 26
ISL8036, ISL8036A
ISL8036A Typical Operating Performance for Dual PWM Operation
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, L1 = L2 = 0.6µH,
FSW = 2.5MHz. (Continued)
LX1 2V/DIV
LX1 1V/DIV
VOUT RIPPLE 20mV/DIV
VOUT RIPPLE 20mV/DIV
IL1 2A/DIV
IL1 0.5A/DIV
FIGURE 37. STEADY STATE OPERATION AT NO LOAD CHANNEL 2
FIGURE 38. STEADY STATE OPERATION AT FULL LOAD CHANNEL 1
LX1 1V/DIV
VOUT1 RIPPLE 50mV/DIV
VOUT RIPPLE 20mV/DIV
IL1 2A/DIV
IL1 2A/DIV
FIGURE 39. STEADY STATE OPERATION AT FULL LOAD CHANNEL 2
FIGURE 40. LOAD TRANSIENT CHANNEL 1
VOUT1 RIPPLE 50mV/DIV
IL1 2A/DIV
FIGURE 41. LOAD TRANSIENT CHANNEL 2
FN6853 Rev 3.00
August 17, 2012
Page 16 of 26
ISL8036, ISL8036A
ISL8036 Typical Operating Performance for Current Sharing PWM
Operation
Unless otherwise noted, operating conditions are: VOUT = 1.8V, IOUT1 + IOUT2 = 0A to 6A, FSW = 1MHz.
100
100
90
90
80
1.5VOUT
1.8VOUT
1.2VOUT
70
EFFICIENCY (%)
EFFICIENCY (%)
2.5VOUT
60
0
1
2
3
4
OUTPUT LOAD (A)
5
60
3.3VOUT
0
1
2
3
4
OUTPUT LOAD (A)
5
6
FIGURE 43. EFFICIENCY vs LOAD, VIN = 5V, TA = +25°C
3.0
1.820
1.815
2.5
OUTPUT VOLTAGE (V)
2.7VIN
2.0
1.5
1.0
5VIN
3.3VIN
0.5
0.0
1.8VOUT
1.2VOUT
70
40
6
FIGURE 42. EFFICIENCY vs LOAD, VIN = 3.3V, TA = +25°C
POWER DISSIPATION (W)
1.5VOUT
50
50
40
2.5VOUT
80
0
1
2
3
4
5
1.810
1.800
2.7VIN
1.795
1.790
6
5VIN
3.3VIN
1.805
0
1
OUTPUT LOAD (A)
2
3
4
OUTPUT LOAD (A)
5
FIGURE 44. POWER DISSIPATION vs LOAD, 1.8V, TA = +25°C
FIGURE 45. VOUT REGULATION vs LOAD, 1.8V, TA = +25°C
1.815
1.820
6
3.3VIN
5VIN
1.805
1.815
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
1.810
3.3VIN
1.800
1.795
2.7VIN
1.805
1.800
2.7VIN
1.795
1.790
1.785
5VIN
1.810
0
1
2
3
4
OUTPUT LOAD (A)
5
FIGURE 46. VOUT REGULATION vs LOAD, 1.8V, TA = -40°C
FN6853 Rev 3.00
August 17, 2012
6
1.790
0
1
2
3
4
OUTPUT LOAD (A)
5
FIGURE 47. VOUT REGULATION vs LOAD, 1.8V, TA = +85°C
Page 17 of 26
6
ISL8036, ISL8036A
ISL8036 Typical Operating Performance for Current Sharing PWM
Operation
Unless otherwise noted, operating conditions are: VOUT = 1.8V, IOUT1 + IOUT2 = 0A to 6A, FSW = 1MHz. (Continued)
1.820
LX1 2V/DIV
OUTPUT VOLTAGE (V)
1.815
1.810
1.805
4A
0A
VOUT RIPPLE 20mV/DIV
1.800
IL1 0.5A/DIV
1.795
1.790
2.5
6A
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
FIGURE 48. OUTPUT VOLTAGE REGULATION vs VIN, TA = +25°C
FIGURE 49. STEADY STATE OPERATION AT NO LOAD CHANNEL 1
LX2 2V/DIV
LX1 2V/DIV
VOUT RIPPLE 20mV/DIV
VOUT RIPPLE 20mV/DIV
IL1 2A/DIV
IL2 2A/DIV
FIGURE 50. STEADY STATE OPERATION WITH FULL LOAD CHANNEL 1
LX1 5V/DIV
LX2 5V/DIV
IL1 1A/DIV
IL2 1A/DIV
FIGURE 52. STEADY STATE OPERATION AT NO LOAD CHANNEL 1
AND 2
FN6853 Rev 3.00
August 17, 2012
FIGURE 51. STEADY STATE OPERATION WITH FULL LOAD CHANNEL 2
LX1 5V/DIV
LX2 5V/DIV
IL1 1A/DIV
IL2 1A/DIV
FIGURE 53. STEADY STATE OPERATION AT FULL LOAD CHANNEL 1
AND 2
Page 18 of 26
ISL8036, ISL8036A
ISL8036 Typical Operating Performance for Current Sharing PWM
Operation
Unless otherwise noted, operating conditions are: VOUT = 1.8V, IOUT1 + IOUT2 = 0A to 6A, FSW = 1MHz. (Continued)
EN1 2V/DIV
VOUT RIPPLE 50mV/DIV
VOUT 1V/DIV
IL1 0.5A/DIV
IL1 2A/DIV
PG1 5V/DIV
FIGURE 54. LOAD TRANSIENT CHANNEL 1
FIGURE 55. SOFT-START WITH NO LOAD CHANNEL 1
EN1 2V/DIV
EN1 5V/DIV
VOUT 1V/DIV
IL1 2A/DIV
VOUT 0.5V/DIV
IL1 0.5A/DIV
PG1 5V/DIV
PG1 5V/DIV
FIGURE 56. SOFT-START AT FULL LOAD CHANNEL 1
FIGURE 57. SOFT-DISCHARGE SHUTDOWN CHANNEL 1
LX1 2V/DIV
SYNC 5V/DIV
SYNC 5V/DIV
LX1 2V/DIV
VOUT RIPPLE 20mV/DIV
VOUT RIPPLE 20mV/DIV
IL1 1A/DIV
FIGURE 58. STEADY STATE OPERATION CH1 AT NO LOAD WITH
FSW = 3MHz
FN6853 Rev 3.00
August 17, 2012
IL1 2A/DIV
FIGURE 59. STEADY STATE OPERATION CH1 AT FULL LOAD WITH
FSW = 3MHz
Page 19 of 26
ISL8036, ISL8036A
ISL8036 Typical Operating Performance for Current Sharing PWM
Operation
Unless otherwise noted, operating conditions are: VOUT = 1.8V, IOUT1 + IOUT2 = 0A to 6A, FSW = 1MHz. (Continued)
LX1 2V/DIV
LX1 2V/DIV
SYNC 5V/DIV
SYNC 5V/DIV
VOUT RIPPLE 20mV/DIV
IL1 1A/DIV
FIGURE 60. STEADY STATE OPERATION CH1 AT NO LOAD WITH
FSW = 6MHz
VOUT RIPPLE 20mV/DIV
IL1 2A/DIV
FIGURE 61. STEADY STATE OPERATION CH1 AT FULL LOAD WITH
FSW = 6MHz
PHASE1 5V/DIV
PHASE1 5V/DIV
VOUT 1V/DIV
IL1 1A/DIV
VOUT 1V/DIV
IL1 1A/DIV
PG1 5V/DIV
FIGURE 62. OUTPUT SHORT CIRCUIT CHANNEL 1
FN6853 Rev 3.00
August 17, 2012
PG1 5V/DIV
FIGURE 63. OUTPUT SHORT CIRCUIT RECOVERY (FROM HICCUP)
CHANNEL 1
Page 20 of 26
ISL8036, ISL8036A
ISL8036A Typical Operating Performance for Current Sharing PWM
Operation
Unless otherwise noted, operating conditions are: VOUT = 1.8V, IOUT1 + IOUT2 = 0A to 6A, L1 = L2 = 0.6µH, FSW = 2.5MHz.
VOUT RIPPLE 20mV/DIV
LX1 5V/DIV
LX1 5V/DIV
LX2 5V/DIV
LX2 5V/DIV
FIGURE 64. STEADY STATE OPERATION AT NO LOAD
FN6853 Rev 3.00
August 17, 2012
VOUT RIPPLE 20mV/DIV
FIGURE 65. STEADY STATE OPERATION AT FULL 6A LOAD
Page 21 of 26
ISL8036, ISL8036A
Theory of Operation
Synchronization Control
The ISL8036, ISL8036A is a dual 3A or current sharing 6A
step-down switching regulator optimized for battery-powered or
mobile applications. The regulator operates at 1MHz (ISL8036) or
2.5MHz (ISL8036A) fixed switching frequency under heavy load
condition. The two channels are 180° out-of-phase operation. The
supply current is typically only 8µA when the regulator is shutdown.
The frequency of operation can be synchronized up to 6MHz by
an external signal applied to the SYNC pin. The 1st falling edge
on the SYNC triggered the rising edge of the PWM ON pulse of
Channel 1. The 2nd falling edge of the SYNC triggers the rising
edge of the PWM ON pulse of the Channel 2. This process
alternate indefinitely allowing 180° output phase operation
between the two channels.
PWM Control Scheme
Pulling the SYNC pin HI (>1.5V) forces the converter into PWM mode
in the next switching cycle regardless of output current. Each of the
channels of the ISL8036, ISL8036A employ the current-mode
pulse-width modulation (PWM) control scheme for fast transient
response and pulse-by-pulse current limiting, as shown in the “Block
Diagram” on page 4 with waveforms in Figure 66. The current loop
consists of the oscillator, the PWM comparator COMP, current
sensing circuit, and the slope compensation for the current loop
stability. The current sensing circuit consists of the resistance of the
P-channel MOSFET when it is turned on and the current sense
amplifier CSA1. The gain for the current sensing circuit is typically
0.2V/A. The control reference for the current loops comes from the
error amplifier EAMP of the voltage loop.
The PWM operation is initialized by the clock from the oscillator.
The P-channel MOSFET is turned on at the beginning of a PWM
cycle and the current in the MOSFET starts to ramp up. When the
sum of the current amplifier CSA1 (or CSA2 on Channel 2) and the
compensation slope (0.46V/µs) reaches the control reference of
the current loop, the PWM comparator COMP sends a signal to the
PWM logic to turn off the P-MOSFET and to turn on the N-channel
MOSFET. The N-MOSFET stays on until the end of the PWM cycle.
Figure 66 shows the typical operating waveforms during the PWM
operation. The dotted lines illustrate the sum of the compensation
ramp and the current-sense amplifier CSA_ output.
VEAMP
VCSA1
Duty
Cycle
IL
VOUT
FIGURE 66. PWM OPERATION WAVEFORMS
The output voltage is regulated by controlling the reference
voltage to the current loop. The bandgap circuit outputs a 0.8V
reference voltage to the voltage control loop. The feedback signal
comes from the VFB pin. The soft-start block only affects the
operation during the start-up and will be discussed separately.
The error amplifier is a transconductance amplifier that converts
the voltage error signal to a current output. The voltage loop is
internally compensated with the 27pF and 390kΩ RC network.
The maximum EAMP voltage output is precisely clamped to the
bandgap voltage (1.172V).
FN6853 Rev 3.00
August 17, 2012
Output Current Sharing
The ISL8036, ISL8036A dual outputs are paralleled for
multi-phase operation in order to support a 6A output. Connect
the FBs together and connect all the COMPs together. Channel 1
and Channel 2 will be 180° out-of-phase. In parallel configuration,
external soft-start should be used to ensure proper full loading
start-up. Before using full load in current sharing mode, PWM
mode should be enabled. Likewise, multiple regulators can be
paralleled by connecting the FBs, COMPs, and SS for higher
current capability. External compensation is required.
Overcurrent Protection
CAS1 and CSA2 are used to monitor Output 1 and Output 2
channels respectively. The overcurrent protection is realized by
monitoring the CSA output with the OCP threshold logic, as
shown in Figure 4. The current sensing circuit has a gain of
0.2V/A, from the P-MOSFET current to the CSA_ output. When
the CSA1 output reaches the threshold, the OCP comparator is
tripped to turn off the P-MOSFET immediately. The overcurrent
function protects the switching converter from a shorted output by
monitoring the current flowing through the upper MOSFETs.
Upon detection of overcurrent condition, the upper MOSFET will
be immediately turned off and will not be turned on again until
the next switching cycle. Upon detection of the initial overcurrent
condition, the Overcurrent Fault Counter is set to 1 and the
Overcurrent Condition Flag is set from LOW to HIGH. If, on the
subsequent cycle, another overcurrent condition is detected, the
OC Fault Counter will be incremented. If there are 17 sequential
OC fault detections, the regulator will be shutdown under an
Overcurrent Fault Condition. An Overcurrent Fault Condition will
result with the regulator attempting to restart in a hiccup mode
with the delay between restarts being 8 soft-start periods. At the
end of the eighth soft-start wait period, the fault counters are
reset and soft-start is attempted again. If the overcurrent
condition goes away prior to the OC Fault Counter reaching a
count of four, the Overcurrent Condition Flag will set back to LOW.
If the negative output current reaches -2.5A, the part enters
Negative Overcurrent Protection. At this point, all switching stops
and the part enters tri-state mode while the pull-down FET is
discharging the output until it reaches normal regulation voltage,
then the IC restarts.
PG
There are two independent power-good signals. PG1 monitors
the Output Channel 1 and PG2 monitors the Output Channel 2.
When powering up, the open-collector Power-on Reset output
holds low for about 1ms after VO reaches the preset voltage. The
PG_ output also serves as a 1ms delayed Power-Good signal.
Page 22 of 26
ISL8036, ISL8036A
UVLO
When the input voltage is below the undervoltage lock out (UVLO)
threshold, the regulator is disabled.
Enable
The enable (EN) input allows the user to control the turning on or
off the regulator for purposes such as power-up sequencing.
When the regulator is enabled, there is typically a 600µs delay
for waking up the bandgap reference. Then the soft start-up
begins.
Soft-start-up
The soft-start-up eliminates the inrush current during the
start-up. The soft-start block outputs a ramp reference to both
the voltage loop and the current loop. The two ramps limit the
inductor current rising speed as well as the output voltage speed
so that the output voltage rises in a controlled fashion. At the
very beginning of the start-up, the output voltage is less than
0.5V; hence the PWM operating frequency is 1/2 of the normal
frequency.
output voltage ripple, the output inductor value can be increased.
The inductor ripple current can be expressed in Equation 2:
VO 

V O   1 – ---------
V

IN
I = --------------------------------------L  fS
(EQ. 2)
The inductor’s saturation current rating needs be at least larger than
the peak current. The ISL8036, ISL8036A protects the typical peak
current 4.8A. The saturation current needs be over 4.8A for maximum
output current application.
ISL8036, ISL8036A uses an internal compensation network and the
output capacitor value is dependent on the output voltage. The
ceramic capacitor is recommended to be X5R or X7R. The
recommended minimum output capacitor values for the ISL8036,
ISL8036A are shown in Table 4.
TABLE 4. OUTPUT CAPACITOR VALUE vs VOUT ISL8036, ISL8036A
VOUT
(V)
COUT
(µF)
L
(µH)
When the IC ramps up at start-up, it can't sink current even at
PWM mode, behaving like in diode emulated mode for the
soft-start time.
0.8
2 x 22
1.0~2.2
1.2
2 x 22
1.0~2.2
1.6
2 x 22
1.0~2.2
Discharge Mode (Soft-Stop)
1.8
2 x 22
1.0~3.3
When a transition to shutdown mode occurs, or the output
undervoltage fault latch is set, its output discharges to PGND
through an internal 100 switch.
2.5
2 x 22
1.0~3.3
3.3
2 x 6.8
1.0~4.7
3.6
10
1.0~4.7
Power MOSFETs
The power MOSFETs are optimize for best efficiency. The
ON-resistance for the P-MOSFET is typically 50m and the
ON-resistance for the N-MOSFET is typical 50m.
In Table 4, the minimum output capacitor value is given for
different output voltages to make sure the whole converter
system is stable.
100% Duty Cycle
Output Voltage Selection
The ISL8036, ISL8036A features 100% duty cycle operation to
maximize the battery life. When the battery voltage drops to a
level that the ISL8036, ISL8036A can no longer maintain the
regulation at the output, the regulator completely turns on the
P-MOSFET. The maximum drop-out voltage under the 100%
duty-cycle operation is the product of the load current and the
ON-resistance of the P-MOSFET.
The output voltage of the regulator can be programmed via an
external resistor divider, which is used to scale the output voltage
relative to the internal reference voltage and feed it back to the
inverting input of the error amplifier. Refer to Figure 2.
Thermal Shutdown
The ISL8036, ISL8036A has built-in thermal protection. When the
internal temperature reaches +150°C, the regulator is completely
shutdown. As the temperature drops to +125°C, the ISL8036,
ISL8036A resumes operation by stepping through a soft start-up.
Applications Information
Output Inductor and Capacitor Selection
To consider steady state and transient operation, ISL8036,
ISL8036A typically uses a 1.5µH output inductor. Higher or lower
inductor value can be used to optimize the total converter system
performance. For example, for a higher output voltage 3.3V
application, in order to decrease the inductor current ripple and
FN6853 Rev 3.00
August 17, 2012
The output voltage programming resistor, R2 (or R5 in
Channel 2), will depend on the desired output voltage of the
regulator. The value for the feedback resistor is typically between
0 and 750k. Let R2 = 124k, then R3 will be:
R 2 x0.8V
R 3 = ---------------------------------V OUT – 0.8V
(EQ. 3)
For better performance, add 12pF in parallel with R2If the
output voltage desired is 0.8V, then leave R3 unpopulated and
short R2.
Input Capacitor Selection
The main functions for the input capacitor are to provide
decoupling of the parasitic inductance and to provide filtering
function to prevent the switching current flowing back to the
battery rail. One 22µF X5R or X7R ceramic capacitor is a good
starting point for the input capacitor selection per channel.
Page 23 of 26
ISL8036, ISL8036A
PCB Layout Recommendation
The PCB layout is a very important converter design step to make
sure the designed converter works well. For ISL8036, ISL8036A,
the power loop is composed of the output inductor L’s, the output
capacitor COUT1 and COUT2, the LX’s pins, and the PGND pin. It is
necessary to make the power loop as small as possible and the
connecting traces among them should be direct, short and wide.
The switching node of the converter, the LX_ pins, and the traces
connected to the node are very noisy, so keep the voltage
feedback trace away from these noisy traces. The FB network
should be as close as possible to its FB pin. SGND should have one
single connection to PGND. The input capacitor should be placed
as closely as possible to the VIN pin. Also, the ground of the input
and output capacitors should be connected as closely as
possible. The heat of the IC is mainly dissipated through the
thermal pad. Maximizing the copper area connected to the
thermal pad is preferable. In addition, a solid ground plane is
helpful for better EMI performance. It is recommended to add at
least 5 vias ground connection within the pad for the best
thermal relief.
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FN6853 Rev 3.00
August 17, 2012
Page 24 of 26
ISL8036, ISL8036A
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to web to make sure you
have the latest Rev.
DATE
July 18, 2012
REVISION
CHANGE
FN6853.3 page 5
Comments added, COMP pin:
COMP pin is NC in dual mode operation, using internal compensation. If SS pin is tied to CSS (without VIN connection),
external compensation is automatically used. Connect an external R,C network on COMP pin for parallel mode
operation.
Comments added, SS pin:
When SS pin is tied to VIN, SS time is 1.5ms. SS pin is tied to VIN only in dual mode operation.
SS pin is tied to CSS only in parallel mode operation, using only external compensation.
page 6 Ordering Information table, added evals:
ISL8036ACRSHEVAL1Z, ISL8036ADUALEVAL1Z, ISL8036CRSHEVAL1Z, ISL8036DUALEVAL1Z
page 15
Figure 33 title correction: "1.8VIN" on the title of these is changed to "1.8VOUT".
Figure 34 title correction: "1.8VIN" on the title of these is changed to "1.8VOUT"
Figure 35 title correction: "1.8VIN" on the title of these is changed to "1.8VOUT"
page 18, Figure 48, deleted "1.8V" in the title since the condition is mentioned in the page header.
page 22
Line 4 in Overcurrent Protection paragraph, instead of "Figure 66" changed to "Figure 4".
"with the delay between restarts being 4 soft-start periods" changed to "with the delay between restarts being 8
soft-start periods".
"end of the fourth soft-start wait period" to "end of the eighth soft-start wait period"
October 14, 2011
FN6853.2 Added “Related Literature” on page 1.
In the “Absolute Maximum Ratings” on page 8, changed:
“LX1, LX2....-1.5V (100ns)/-0.3V (DC) to 6.5V (DC) or 7V (20ms)”
to:
“LX1, LX2....-3V/(10ns)/-1.5V (100ns)/-0.3V (DC) to 6.5V (DC) or 7V (20ms)/8.5V(10ns)”
October 12, 2010
FN6853.1 In Table 3 on page 3, corrected FSW for ISL8036 from 1Hz to 1MHz.
September 28, 2010 FN6853.0 Initial release.
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FN6853 Rev 3.00
August 17, 2012
Page 25 of 26
ISL8036, ISL8036A
Package Outline Drawing
L24.4x4D
24 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE
Rev 2, 10/06
4.00
4X 2.5
A
20X 0.50
B
PIN 1
INDEX AREA
PIN #1 CORNER
(C 0 . 25)
24
19
1
18
4.00
2 . 50 ± 0 . 15
13
0.15
(4X)
12
7
0.10 M C A B
0 . 07
24X 0 . 23 +- 0
. 05 4
24X 0 . 4 ± 0 . 1
TOP VIEW
BOTTOM VIEW
SEE DETAIL "X"
0.10 C
C
0 . 90 ± 0 . 1
BASE PLANE
( 3 . 8 TYP )
SEATING PLANE
0.08 C
SIDE VIEW
(
2 . 50 )
( 20X 0 . 5 )
C
0 . 2 REF
5
( 24X 0 . 25 )
0 . 00 MIN.
0 . 05 MAX.
( 24X 0 . 6 )
DETAIL "X"
TYPICAL RECOMMENDED LAND PATTERN
NOTES:
1. Dimensions are in millimeters.
Dimensions in ( ) for Reference Only.
2. Dimensioning and tolerancing conform to AMSE Y14.5m-1994.
3. Unless otherwise specified, tolerance : Decimal ± 0.05
4. Dimension b applies to the metallized terminal and is measured
between 0.15mm and 0.30mm from the terminal tip.
5. Tiebar shown (if present) is a non-functional feature.
6. The configuration of the pin #1 identifier is optional, but must be
located within the zone indicated. The pin #1 indentifier may be
either a mold or mark feature.
FN6853 Rev 3.00
August 17, 2012
Page 26 of 26