USER’S MANUAL
EN1
GND
DDR
VSEN1
VIN
PG1
26
25
24
23
22
21
1
2
3
4
5
6
7
8
VCC
27
28
VOUT1
9
10
11
12
13
14
18
17
16
15
19
20
ISEN1
LGATE1
PGND1
BOOT1
UGATE1
PHASE1
ISEN2
LGATE2
PGND2
BOOT2
UGATE2
PHASE2
EN2
VSEN2
VOUT2
OCSET2OCSET1
SOFT1 SOFT2
PG2/REF
ISL6225
SSOP-28
ISL6225EVAL2
Dual Switcher Evaluation Board Setup Procedure
General Description
This document describes the setup procedure for the
ISL6225 Evaluation Board dual switcher implementation.
The ISL6225 can control two output voltages adjustable from
0.9V to 5.5V. The ISL6225 combines two synchronous PWM
voltage regulators into a single IC. PWM1 and PWM2 output
voltages are set by a simple feedback voltage divider
connected across the outputs to GND. The feedback voltage
divider outputs are 0.9VDC, which are connected to the
VSEN1 and VSEN2 pins.
Automatic mode selection of constant-frequency synchronous
rectification at heavy load, and hysteretic diode-emulation at
light load, assure high efficiency over a wide range of
conditions. The hysteretic mode of operation can be disabled
separately on each PWM converter if constant-frequency
continuous-conduction operation is desired for all load levels.
Efficiency is further enhanced by using the lower MOSFET
R
Voltage-feed-forward ramp modulation, current mode control,
and internal feedback compensation provide fast response to
input voltage and output load transients.
In dual power supply applications the ISL6225 monitors the
output voltage of both CH1 and CH2. An independent
PGOOD (power good) signal is asserted for each channel
after its soft-start sequence has completed, and the output
voltage is within ±10% of the set point.
as the current sense element.
DS(ON)
AN1058
Rev 0.00
May 2003
Features
• Provides regulated output voltage in the range of 0.9V–5.5V
- High efficiency over wide load range
- Synchronous buck converter with hysteretic operation at
light load
- Inhibit Hysteretic mode on one, or both channels
• No current-sense resistor required
- Uses MOSFET R
DS(ON)
- Optional current-sense resistor for precision OverCurrent
• Over-Voltage, Under-Voltage and Over-Current protection
on both channels
• Under-voltage lock-out on VCC pin
• Dual input voltage mode operation
- Operates directly from battery 5V to 24V input
- Operates from 3.3V or 5V system rail
- VCC from 5V only
• Excellent dynamic response
- Combined voltage feed-forward and average current
mode control
• Power-good signal for each channel
• 300kHz switching frequency
- 180° channel to channel phase operation
Pinout
Built-in over-voltage protection prevents the output from
going above 115% of the set point by holding the lower
MOSFET on and the upper MOSFET off. When the output
voltage decays below the over-voltage threshold, normal
operation automatically resumes. Once the soft-start
sequence has completed, under-voltage protection will latch
the channel off if the output drops below 75% of its set point
value.
Adjustable over-current protection (OCP) monitors the
voltage drop across the R
of the lower MOSFET. If
DS(ON)
more precise current-sensing is required, an external current
sense resistor may be used.
Ordering Information
PART NUMBER TEMP. (oC) PACKAGE PKG. DWG. #
ISL6225CA -10 to 85 28 Ld SSOP M28.15
ISL6225CA-T -10 to 85 28 Ld SSOP Tape
AN1058 Rev 0.00 Page 1 of 11
May 2003
and Reel
M28.15
What’s Inside
This Evaluation Board Kit contains the following materials:
• ISL6225EVAL2 Evaluation Board
• ISL6225EVAL2 Board Evaluation Document
What is Needed
The following items will be needed to perform a complete
evaluation:
• 4 channel oscilloscope with probes
• 2 electronic loads
• 2 laboratory power supplies
• Precision digital multimeters
• Digital pulse generator
AN1058 Rev 0.00 Page 2 of 11
May 2003
ISL6225EVAL2
JP1 SHUNTED TOWARD VIN>5V
JP2 SHUNTED
1.
JP4 SHUNTED TOWARD FCCM2
JP6 - NO SHUNT
JP5 - NO SHUNT
JP7 SHUNTED
JP3 SHUNTED TOWARD FCCM1
FIGURE 1. INITIAL SHUNT PLACEMENT FOR ISL6225EVAL2
AN1058 Rev 0.00 Page 3 of 11
May 2003
ISL6225EVAL2
S
CONNECT THE
POSITIVE
TERMINAL (+) OF
THE 5VDC POWER
SUPPLY AND THE
POSITIVE
TERMINAL (+) OF
THE DVM TO J4
VCC
CONNECT THE
NEGATIVE TERMINAL
(-) OF THE 5VDC
POWER SUPPLY AND
NEGATIVE TERMINAL
(-) OF THE DVM TO
THE GND TERMINAL
J14
CONNECT THE
POSITIVE TERMINAL
(+) OF THE
ADJUSTABLE 24VDC
POWER SUPPLY TO
THE VIN TERMINALS
J2 AND J3
CONNECT THE
NEGATIVE TERMINAL
(-) OF THE 24VDC
POWER SUPPLY AND
THE NEGATIVE
TERMINAL (-) OF THE
DVM TO THE GND
TERMINAL J1
FIGURE 2. WIRING CONNECTIONS FOR ISL6225EVAL2
CONNECT THE
POSITIVE TERMINAL
(+) OF THE DVM TO
ONE OF THE VIN
TERMINALS J2 OR
J3
CONNECT THE
NEGATIVE
TERMINAL (-) OF
THE ELECTRONIC
LOAD AND THE DVM
TO THE GND
TERMINAL J8
CONNECT THE
POSITIVE TERMINAL
(+) OF THE
ELECTRONIC LOAD
AND THE DVM TO
THE VOUT1
TERMINAL J5
CONNECT THE
POSITIVE TERMINAL
(+) OF THE
ELECTRONIC LOAD
AND THE DVM TO
THE VOUT2
TERMINAL J6
CONNECT THE
NEGATIVE
TERMINAL (-) OF
THE ELECTRONIC
LOAD AND THE DVM
TO THE GND
TERMINAL J7
CR1 — CHANNEL 1
POWER GOOD
INDICATOR LED
CR2 — CHANNEL 2
POWER GOOD
INDICATOR LED
OSCILLOSCOPE TIP MEASUREMENT POINT FOR VOUT1
OSCILLOSCOPE TIP
MEASUREMENT
POINT FOR PHASE2
OSCILLOSCOPE TIP
MEASUREMENT
POINT FOR PHASE1
OSCILLOSCOPE TIP MEASUREMENT POINT FOR VOUT2
ISL6225EVAL2
TABLE 1. DETAILED DESCRIPTION OF THE JUMPER
SETTINGS
JUMPER POSITION FUNCTION
*VIN>5V *Input Voltage greater than 5V
JP1
VIN=5V Input Voltage 3.3V to 5V operation
*Shunted *An AmpMeter may be connected across
JP2
*FCCM1 *PWM1 Fixed Continuous Conduction
JP3
Away from
FCCM1
*FCCM2 *PWM2 Fixed Continuous Conduction
JP4
Away from
FCCM2
Shunted CH1 enabled
JP5
* Removed * CH1 disabled
Shunted CH2 enabled
JP6
*Removed * CH2 disabled
*Shunted * One VIN supply for both CH1 and CH2
JP7
Removed Separate VIN supplies for CH1 and CH2
NOTE: * = Initial Setting
.
TABLE 2. LED CONDITION INDICATORS
LED CONDITION CONDITION RESULT
CR1
CR2
these pins to measure IC and GATE Drive
Current only
Mode
PWM1 Hysteretic Operation
enabled
Mode
PWM2 Hysteretic Operation enabled
Green VOUT1 Within PGOOD
Range
Red VOUT1 Outside PGOOD
Range
Green VOUT2 Within PGOOD
Range
Red VOUT1 Outside PGOOD
Range
Quick Setup
• The VIN Power Supply must always be the first supply on
and the last supply off.
•The 5V V
• Make sure the power is off before moving any jumpers,
except EN1 and EN2.
Step 1: Set the output voltage of the 5V adjustable power
supply to zero volts. Connect the positive terminal (+)
of the power supply to the VCC terminal J4. Connect
the negative terminal (-) of the 5VDC power supply to
the GND terminal J14.
Do not apply power yet
Power Supply must be between 5V ± 5%.
CC
Step 2: Connect the positive terminal (+) of a DVM to the
VCC terminal J4. Connect the negative terminal (-) of
the DVM to the GND terminal J14.
Step 3: Set the adjustable 24VDC output voltage to zero
volts. Connect the positive terminal (+) of the power
supply to the VIN terminals J2 and J3. Connect the
negative terminal (-) of the 24VDC power supply to
the GND terminal J1.
Do not apply power yet
Step 4: Connect the positive terminal (+) of a DVM to one of
the VIN terminals J2 or J3. Connect the negative
terminal (-) of the DVM to the GND terminal J1.
Step 5: Connect the positive terminal (+) of the electronic
load and the DVM to the VOUT1 terminal J5.
Connect the negative terminal (-) of the electronic
load and the DVM to the GND terminal J8.
Step 6: Connect the positive terminal (+) of the electronic
load and the DVM to the VOUT2 terminal J6.
Connect the negative terminal (-) of the electronic
load and the DVM to the GND terminal J7.
Step 7: Take the adjustable 24VDC power supply that is
connected to the VIN terminals J2 and J3 and make
sure the output voltage is set to zero VOLTS.
Step 8: Turn on the 24VDC power supply.
Step 9: While reading the DVM, increase the output voltage
of the 24VDC power supply to 5.0 VDC.
Step 10: Turn on the 5VDC power supply.
Step 11: While reading the DVM, increase the output voltage
of the 5VDC power supply to 5VDC.
Step 12: Install the EN1 shunt jumper JP5.
Step 13: Install the EN2 shunt jumper JP6.
NOTE: Terminals J1 (EN1) and J12 (EN2) may be connected to a
Pulse generator for controlled on/off operation and may be observed
with an oscilloscope.
Step 14: Read the DVM connected to the VOUT1
terminal J5.
Step 15: Read the DVM connected to the VOUT2
terminal J6.
The 24V VIN Power Supply may be adjusted between 5-24
VDC.
If Hysteretic operation is desired move jumper J3 for PWM1 or
JP4 for PWM2, to the position opposite the silk screen
“FCCM”.
The Electronic Load can be connected to VOUT1 and VOUT2
for load regulator measurement.
Make sure the power is off before moving the jumpers.
Terminals J1 (EN1) and J12 (EN2) may be connected to a
Pulse generator for controlled on/off operation and may be
observed with an oscilloscope.
Make sure the enable voltage is less than 5V V
CC
.
AN1058 Rev 0.00 Page 4 of 11
May 2003
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