19-1888; Rev 0; 12/00
MAX1765 Evaluation Kit
The MAX1765 features an internal N-channel MOSFET
switch and a P-channel synchronous rectifier, and a
pin-selectable forced pulse-width modulation (PWM)
mode. The MAX1765 EV kit demonstrates low quiescent current and high efficiency (up to 96%) for maximum battery life. Operation at 1MHz allows the use of
tiny surface-mount components.
Features
♦ Operation from Inputs as Low as 0.7V
♦ Output Voltages
+3.3V Output at 800mA (DC-DC)
+2.85V Output at 500mA (LDO)
♦ Both Outputs Are Adjustable with External
Resistors
♦ Two Complete Circuits (Both Package Types)
♦ 1µA IC Shutdown Current
♦ 1MHz PWM Switching Frequency
(for Small, Surface-Mount Components)
♦ Programmable Operating Mode
♦ Built-In 500mA LDO Linear Regulator
♦ Fully Assembled and Tested
Ordering Information
PART
TEMP. RANGE
MAX1765EVKIT
*Exposed paddle
0°C to +70°C
IC PACKAGE
16 QSOP, 16 TSSOP-EP*
Component List
DESIGNATION QTY*
DESCRIPTION
DESIGNATION QTY*
DESCRIPTION
D2
1
1A, 30V Schottky diode
Nihon EP10QY03
100µF, 6.3V low-ESR electrolytic caps
(POSCAP) Sanyo 6TPC100M
JU1–JU4,
JU7–JU10
8
3-pin headers
6
1µF, 10V X5R ceramic caps (0805)
Taiyo Yuden LMK212BJ105MG
JU5, JU11
2
2-pin headers
L1, L2
2
3.3µH inductors
Coilcraft DO1606T-332
2
0.1µF, 50V X5R ceramic caps (0805)
Taiyo Yuden UMK212BJ104KG
R1, R9
2
165kΩ ±1% resistors (0805)
2
0.68µF, 10V X5R ceramic caps (0805)
Taiyo Yuden LMK212BJ684KG
R2, R8
2
100kΩ ±1% resistors (0805)
Not installed (0805)
2
R3, R4, R6,
R7, R10, R11,
R13, R14
0
C6, C16
4.7µF, 6.3V X5R ceramic caps (0805)
Taiyo Yuden JMK212BJ475KG
2
4.7Ω ±5% resistors (0805)
2
0.22µF, 25V X7R ceramic caps (1206)
Taiyo Yuden TMK316BJ224KF
R5, R12
C8, C18
U1
1
MAX1765EEE (16 QSOP)
C9, C19
0
Not installed (0805)
C1, C11
2
33µF, 16V low-ESR electrolytic caps
(POSCAP) Sanyo 16TPC33M
C2, C12
2
C3, C7, C13,
C17, C21, C22
C4, C14
C5, C15
C10, C20
D1
0
0
Not installed (POSCAP D2)
Not installed
Nihon EP10QY03 (recommended for
low-voltage startup)
U2
1
MAX1765EUE (16 TSSOP-EP)
None
10
Shunts (JU1–JU5, JU7–JU11)
None
1
MAX1765 PC board
None
1
MAX1765 data sheet
None
1
MAX1765 EV kit data sheet
*Quantities are for both circuits.
________________________________________________________________ Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Evaluates: MAX1765
General Description
The MAX1765 evaluation kit (EV kit) is a fully assembled
and tested surface-mount circuit board that contains
two separate switching-regulator and linear-regulator
circuits. Both circuits are configured for a +3.3V DC-DC
output, which provides up to 800mA of current. They
also contain a low-dropout (LDO) linear regulator that is
configured for a +2.85V output and provides up to
500mA at the output. The two circuits differ only in their
package type: the low-power circuit (left side) uses a
16-pin QSOP that can dissipate up to 696mW, while the
high-power circuit (right side) uses a 16-pin TSSOP-EP
that can dissipate up to 1700mW.
Evaluates: MAX1765
MAX1765 Evaluation Kit
Component Suppliers
SUPPLIER
PHONE
FAX
Coilcraft
847-639-6400
847-639-1469
Nihon USA
661-867-2555
661-867-2698
Sanyo USA
619-661-6835
619-661-1055
Taiyo Yuden
408-573-4150
408-573-4159
Note: Please indicate that you are using the MAX1765 when
contacting these component suppliers.
Quick Reference
The MAX1765 EV kit is fully assembled and tested.
Follow these steps to verify board operation. Do not
turn on the power supply until all connections are
completed.
Both circuits require a +1.1V to +3.2V input voltage
range. The LDO linear regulators can be powered from
the switching regulator output (POUT) or an external
DC voltage source.
The circuits differ in their package type. The low-power
circuit (left side) features a 16-pin QSOP, while the
high-power circuit (right side) features a thermally
enhanced 16-pin TSSOP-EP.
The switching regulators’ output voltages can be
adjusted from +2.5V to +5.5V with external resistors.
The MAX1765 EV kit permits jumper-selectable operational modes: normal (heavy-load PWM/light-load PFM)
mode, track mode, forced PWM mode, and forced
PWM mode with the internal oscillator synchronized to
an external clock.
Jumper Selection
Low-Power Circuit (Left Side)
1) Connect a voltmeter to the POUT pad.
2) Verify that shunts JU1 (ONA), JU2 (CLK/SEL), and
JU4 (ONL) are across pins 1 and 2 and that shunt
JU3 (TRACK) is across pins 2 and 3. Verify that a
shunt is on jumper JU5.
3) Connect a +1.1VDC to +3.2VDC power supply to the
PIN pad. Connect the supply ground to the GND pad.
4) Turn on the power supply and verify that the main
output (POUT) is +3.3V.
5) Verify that the LDO linear regulator output (OUTL) is
+2.85V.
For instructions on selecting the feedback resistors for
other output voltages, see the Evaluating Other Output
Voltages section.
High-Power Circuit (Right Side)
1) Connect a voltmeter to the POUT pad.
2) Verify that shunts JU7 (ONA), JU8 (CLK/SEL), and
JU10 (ONL) are across pins 1 and 2 and that shunt
JU9 (TRACK) is across pins 2 and 3. Verify that a
shunt is on jumper JU11.
3) Connect a +1.1VDC to +3.2VDC power supply to
the PIN pad. Connect the supply ground to the
GND pad.
4) Turn on the power supply and verify that the main
output (POUT) is +3.3V.
5) Verify that the LDO Linear Regulator output (OUTL)
is +2.85V.
For instructions on selecting the feedback resistors for
other output voltages, see the Evaluating Other Output
Voltages (Both Circuits) section.
Shutdown Mode (Both Circuits)
The MAX1765 EV kit features a shutdown mode that
reduces the MAX1765 quiescent current to less than 1µA
(typ), preserving battery life. The 3-pin jumpers, JU1 and
JU7, select the shutdown mode for the MAX1765. Table
1 lists the selectable jumper options.
CLK/SEL Operating Mode (Both Circuits)
Jumpers JU2 and JU8 control the CLK/SEL pin operating
mode for the left and right circuits, respectively. Options
include low-noise forced PWM mode, normal mode, and
external clock source driving the CLK/SEL pin. The external clock source must operate in the 500kHz to 1200kHz
range. Table 2 lists the CLK/SEL jumper options.
Table 1. Jumper JU1, JU7 Functions
SHUNT
LOCATION
ONA PIN
1, 2
Connected to POUT
MAX1765 enabled,
POUT = +3.3V
2, 3
Connected to GND
Shutdown mode,
POUT = PIN - VDIODE
Table 2. Jumper JU2, JU8 Functions
SHUNT
LOCATION
CLK/SEL PIN
1, 2
Connected to POUT
Forced PWM mode:
PWM operation at all
loads
2, 3
Connected to GND
Normal mode: PFM at
light load and PWM at
heavy load
None
Clock connected to
CLK/SEL pad
PWM mode synchronized to external
500kHz to 1200kHz
range clock
Detailed Description
The MAX1765 EV kit contains two separate boost
switching-regulator circuits that provide +3.3VDC output and linear regulators that provide +2.85V output.
2
MAX1765
OUTPUT
OPERATING MODE
_______________________________________________________________________________________
MAX1765 Evaluation Kit
LDO Linear Regulator Shutdown Mode
(Both Circuits)
The MAX1765 EV kit features a shutdown mode for the
built-in LDO linear regulator. The 3-pin jumpers, JU4
and JU10, disable and enable the left and right LDO
linear regulators, respectively. Table 4 lists the selectable jumper options.
LDO Linear Regulator Source Selection
(Both Circuits)
The MAX1765 EV kit allows each built-in LDO linear
regulator to be powered from the boost switching regulator or an external voltage source. Jumpers JU5 and
JU11 select the DC voltage source for the left and right
LDO linear regulators, respectively. Table 5 lists the
jumper options.
Table 3. Jumper JU3, JU9 Functions
SHUNT
LOCATION
TRACK PIN
1, 2
Connected to POUT
Track mode enabled
2, 3
Connected to GND
Normal operation
OPERATING MODE
Table 4. Jumper JU4, JU10 Functions
SHUNT
LOCATION
ONL PIN
LDO OPERATING
MODE
1, 2
Connected to POUT
Linear regulator
enabled
2, 3
Connected to GND
Linear regulator disabled
Table 5. Jumper JU5, JU11 Functions
LOCATION
INL PIN
LDO POWER
SOURCE
Installed
Connected to
POUT
POUT supplies the
LDO linear regulator
power
None
Connected to
external DC
source
External source supplies the LDO linear
regulator power
Note: INL must be powered to use the boost switching regulator circuit. If the LDO linear regulator is not used, INL must be
connected to POUT (JU5 or JU11 installed) or a higher external source applied to the INL pad.
Evaluating Lower Startup Input Voltages
The MAX1765 EV kit can operate from DC supply voltages down to +0.7V. When PIN is below +1.1V, a
Schottky diode is required to guarantee startup below
1.1V. A Shottky diode is supplied with the high-power
circuit (right side), but the user must add it to the lowpower circuit (left side). Refer to the Selecting the
Output Diode section in the MAX1765 data sheet for
instructions on selecting D1.
Evaluating Other Output Voltages
(Both Circuits)
The MAX1765 EV kit’s boost switching regulator outputs
are set to +3.3V by feedback resistors R1, R2, R8, and
R9. To generate output voltages other than +3.3V (+2.5V
to +5.5V), select different external voltage-divider resistors (R1, R2 left side and R8, R9 right side). Refer to
Setting the Output Voltages section in the MAX1765 data
sheet for instructions on selecting the resistors.
Evaluating Other LDO Linear Regulator
Output Voltages (Both Circuits)
The MAX1765 EV kit’s LDO linear regulator output
(OUTL) has been set to +2.85V by shorting the FBL pin
to ground. To generate output voltages other than
+2.85V (+1.25V to +5V), cut open the PC board trace
across resistor R4 or R10 for the left and right sides,
respectively. Select different external voltage-divider
resistors. Refer to the Setting the Output Voltages section in the MAX1765 data sheet for instructions on the
resistors (R3, R4 left side or R10, R11 right side).
Evaluating Other Current Limits
(Both Circuits)
The EV kit inductor current limit can be set from 400mA
to 1250mA. The EV kit is factory configured for a
1250mA inductor current limit. To evaluate other current
limits, cut open the PC board trace shorting R6 or R14
for the left and right sides, respectively. Resistors must
be selected and installed to set the current limit. Refer
to Setting the Switch Current Limit and Soft-Start section of the MAX1765 data sheet for selecting the resistors (R6, R7 left side or R13, R14 right side).
Enabling Soft-Start (Both Circuits)
The MAX1765 soft-start feature will limit in-rush current
during startup. To evaluate soft-start, cut open the PC
board trace shorting R6 or R14 for the left and right
sides, respectively. Install capacitor C9 or C19 and
resistors R6 or R14. Refer to the Setting the Switch
Current Limit and Soft-Start section in the MAX1765
data sheet for instructions on selecting C9 or C19 and
R6 or R14 to activate soft-start.
_______________________________________________________________________________________
3
Evaluates: MAX1765
TRACK Operating Mode (Both Circuits)
The MAX1765 EV kit features a track mode where
POUT is set to +0.5V above the LDO linear regulator
output voltage to improve efficiency. Use JU3 and JU9
to select track mode for either circuit. Table 3 lists the
selectable jumper options.
Evaluates: MAX1765
MAX1765 Evaluation Kit
PIN
+0.7V TO +3.2V
GND
L1
3.3µH
C1
33µF
16V
9
ONB
LX
POUT
ONA
3
2
JU1
7
1
POUT
CLK/SEL
POUT
+3.3V
D1
(OPEN)
C10
(OPEN)
11
C2
100µF
6.3V
C3
1µF
10V
POUT
GND
12
C4
0.1µF
ONA
U1
JU2
1
2
PWM
3
PFM
3
2
JU3
R5
4.7Ω
5%
MAX1765
8
CLK/SEL
OUT
6
C5
0.68µF
15
TRACK
FB
R1
165kΩ
1%
R2
100kΩ
1%
5
1
3
C8
0.22µF
REF
OUTL
+2.85V
OUTL
14
R6
(SHORT PC TRACE)
2
C9
(OPEN)
R7
(OPEN)
16
ISET
FBL
ONL
INL
GND
4
1
2
R3
(OPEN)
1
13
R4
(SHORT PC TRACE)
C6
4.7µF
6.3V
PGND
10
C21
1µF
3
JU4
ONL
JU5
INL
POUT
Figure 1. MAX1765 EV Kit Schematic (Left Side)
4
_______________________________________________________________________________________
C7
1µF
10V
GND
MAX1765 Evaluation Kit
GND
L2
3.3µH
C11
33µF
16V
ONB
LX
POUT
ONA
3
2
JU7
7
1
POUT
CLK/SEL
POUT
+3.3V
D2
9
C20
(OPEN)
11
C12
100µF
6.3V
C13
1µF
10V
POUT
GND
12
C14
0.1µF
ONA
U2
JU8
1
2
PWM
3
PFM
3
2
JU9
R12
4.7Ω
5%
MAX1765
8
CLK/SEL
OUT
6
C15
0.68µF
15
TRACK
FB
R9
165kΩ
1%
R8
100kΩ
1%
5
1
3
C18
0.22µF
Evaluates: MAX1765
PIN
+0.7V TO +3.2V
REF
OUTL
+2.85V
OUTL
14
R14
(SHORT PC TRACE)
2
C19
(OPEN)
R13
(OPEN)
16
ISET
FBL
ONL
INL
GND
4
1
2
R11
(OPEN)
1
13
R10
(SHORT PC TRACE)
C16
4.7µF
6.3V
C17
1µF
10V
GND
PGND
10
C22
1µF
3
JU10
ONL
JU11
POUT
INL
Figure 2. MAX1765 EV Kit Schematic (Right Side)
_______________________________________________________________________________________
5
Evaluates: MAX1765
MAX1765 Evaluation Kit
1.0"
Figure 3. MAX1765 EV Kit Component Placement Guide—Component Side
1.0"
Figure 4. MAX1765 EV Kit PC Board Layout—Component Side
6
_______________________________________________________________________________________
MAX1765 Evaluation Kit
Evaluates: MAX1765
1.0"
Figure 5. MAX1765 EV Kit PC Board Layout—Solder Side
1.0"
Figure 6. MAX1765 EV Kit Component Placement Guide—Solder Side
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
7 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2000 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
