19-1888; Rev 0; 12/00
MAX1765 Evaluation Kit
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.
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 quies-
cent current and high efficiency (up to 96%) for maxi-
mum battery life. Operation at 1MHz allows the use of
tiny surface-mount components.
o
Output Voltages
+3.3V Output at 800mA (DC-DC)
+2.85V Output at 500mA (LDO)
o
Both Outputs Are Adjustable with External
Resistors
o
Two Complete Circuits (Both Package Types)
o
1µA IC Shutdown Current
o
1MHz PWM Switching Frequency
(for Small, Surface-Mount Components)
o
Programmable Operating Mode
o
Built-In 500mA LDO Linear Regulator
o
Fully Assembled and Tested
Features
o
Operation from Inputs as Low as 0.7V
Evaluates: MAX1765
Ordering Information
PART
MAX1765EVKIT
*Exposed paddle
TEMP. RANGE
0°C to +70°C
IC PACKAGE
16 QSOP, 16 TSSOP-EP*
Component List
DESIGNATION QTY*
C1, C11
C2, C12
C3, C7, C13,
C17, C21, C22
C4, C14
C5, C15
C6, C16
C8, C18
C9, C19
C10, C20
D1
2
2
6
2
2
2
2
0
0
0
DESCRIPTION
33µF, 16V low-ESR electrolytic caps
(POSCAP) Sanyo 16TPC33M
100µF, 6.3V low-ESR electrolytic caps
(POSCAP) Sanyo 6TPC100M
1µF, 10V X5R ceramic caps (0805)
Taiyo Yuden LMK212BJ105MG
0.1µF, 50V X5R ceramic caps (0805)
Taiyo Yuden UMK212BJ104KG
0.68µF, 10V X5R ceramic caps (0805)
Taiyo Yuden LMK212BJ684KG
4.7µF, 6.3V X5R ceramic caps (0805)
Taiyo Yuden JMK212BJ475KG
0.22µF, 25V X7R ceramic caps (1206)
Taiyo Yuden TMK316BJ224KF
Not installed (0805)
Not installed (POSCAP D2)
Not installed
Nihon EP10QY03 (recommended for
low-voltage startup)
DESIGNATION QTY*
D2
JU1–JU4,
JU7–JU10
JU5, JU11
L1, L2
R1, R9
R2, R8
R3, R4, R6,
R7, R10, R11,
R13, R14
R5, R12
U1
U2
None
None
None
None
1
8
2
2
2
2
0
2
1
1
10
1
1
1
DESCRIPTION
1A, 30V Schottky diode
Nihon EP10QY03
3-pin headers
2-pin headers
3.3µH inductors
Coilcraft DO1606T-332
165kΩ ±1% resistors (0805)
100kΩ ±1% resistors (0805)
Not installed (0805)
4.7Ω ±5% resistors (0805)
MAX1765EEE (16 QSOP)
MAX1765EUE (16 TSSOP-EP)
Shunts (JU1–JU5, JU7–JU11)
MAX1765 PC board
MAX1765 data sheet
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.
MAX1765 Evaluation Kit
Evaluates: MAX1765
Component Suppliers
SUPPLIER
Coilcraft
Nihon USA
Sanyo USA
Taiyo Yuden
PHONE
847-639-6400
661-867-2555
619-661-6835
408-573-4150
FAX
847-639-1469
661-867-2698
619-661-1055
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 opera-
tional 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.
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.
Jumper Selection
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 exter-
nal 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
1, 2
2, 3
ONA PIN
Connected to POUT
Connected to GND
MAX1765
OUTPUT
MAX1765 enabled,
POUT = +3.3V
Shutdown mode,
POUT = PIN - V
DIODE
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.
Table 2. Jumper JU2, JU8 Functions
SHUNT
LOCATION
1, 2
CLK/SEL PIN
OPERATING MODE
Forced PWM mode:
PWM operation at all
loads
Normal mode: PFM at
light load and PWM at
heavy load
PWM mode synchro-
nized to external
500kHz to 1200kHz
range clock
Connected to POUT
2, 3
Connected to GND
Detailed Description
The MAX1765 EV kit contains two separate boost
switching-regulator circuits that provide +3.3VDC out-
put and linear regulators that provide +2.85V output.
2
None
Clock connected to
CLK/SEL pad
_______________________________________________________________________________________
MAX1765 Evaluation Kit
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.
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 selec-
table 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 regu-
lator 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.
Evaluating Lower Startup Input Voltages
The MAX1765 EV kit can operate from DC supply volt-
ages 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 low-
power circuit (left side). Refer to the
Selecting the
Output Diode
section in the MAX1765 data sheet for
instructions on selecting D1.
Evaluates: MAX1765
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 resis-
tors (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
sec-
tion in the MAX1765 data sheet for instructions on the
resistors (R3, R4 left side or R10, R11 right side).
Table 3. Jumper JU3, JU9 Functions
SHUNT
LOCATION
1, 2
2, 3
TRACK PIN
Connected to POUT
Connected to GND
OPERATING MODE
Track mode enabled
Normal operation
Table 4. Jumper JU4, JU10 Functions
SHUNT
LOCATION
1, 2
2, 3
ONL PIN
Connected to POUT
Connected to GND
LDO OPERATING
MODE
Linear regulator
enabled
Linear regulator dis-
abled
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
sec-
tion of the MAX1765 data sheet for selecting the resis-
tors (R6, R7 left side or R13, R14 right side).
Table 5. Jumper JU5, JU11 Functions
LOCATION
INL PIN
Connected to
POUT
Connected to
external DC
source
LDO POWER
SOURCE
POUT supplies the
LDO linear regulator
power
External source sup-
plies the LDO linear
regulator power
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.
Installed
None
Note:
INL must be powered to use the boost switching regula-
tor circuit. If the LDO linear regulator is not used, INL must be
connected to POUT (JU5 or JU11 installed) or a higher exter-
nal source applied to the INL pad.
_______________________________________________________________________________________
3
MAX1765 Evaluation Kit
Evaluates: MAX1765
PIN
+0.7V TO +3.2V
GND
C1
33µF
16V
POUT
+3.3V
C2
100µF
6.3V
C3
1µF
10V
POUT
GND
L1
3.3µH
D1
(OPEN)
9
ONB
LX
11
C10
(OPEN)
POUT
ONA
3
2
1
POUT
CLK/SEL
1
2
3
JU2
PWM
PFM
8
JU1
7
ONA
12
C4
0.1µF
U1
MAX1765
CLK/SEL
OUT
6
R5
4.7Ω
5%
C5
0.68µF
R1
165kΩ
1%
R2
100kΩ
1%
3
2
1
JU3
15
TRACK
FB
5
+2.85V
OUTL
R3
(OPEN)
R4
(SHORT PC TRACE)
3
C8
0.22µF
R6
(SHORT PC TRACE)
2
R7
(OPEN)
C9
(OPEN)
16
REF
OUTL
14
ISET
ONL
GND
4
FBL
1
C6
4.7µF
6.3V
C7
1µF
10V
GND
INL
PGND
10
13
1
2
JU4
3
C21
1µF
ONL
JU5
INL
POUT
Figure 1. MAX1765 EV Kit Schematic (Left Side)
4
_______________________________________________________________________________________
MAX1765 Evaluation Kit
Evaluates: MAX1765
PIN
+0.7V TO +3.2V
GND
C11
33µF
16V
L2
3.3µH
D2
C12
100µF
6.3V
C13
1µF
10V
POUT
+3.3V
9
ONB
LX
11
C20
(OPEN)
POUT
GND
POUT
ONA
3
2
1
POUT
CLK/SEL
1
2
3
JU8
PWM
PFM
8
JU7
7
ONA
12
C14
0.1µF
U2
MAX1765
CLK/SEL
OUT
6
C15
0.68µF
R12
4.7Ω
5%
R9
165kΩ
1%
R8
100kΩ
1%
3
2
1
JU9
15
TRACK
FB
5
+2.85V
OUTL
R11
(OPEN)
R10
(SHORT PC TRACE)
3
C18
0.22µF
R14
(SHORT PC TRACE)
2
R13
(OPEN)
C19
(OPEN)
16
REF
OUTL
14
ISET
ONL
GND
4
FBL
1
C16
4.7µF
6.3V
C17
1µF
10V
GND
INL
PGND
10
13
1
2
3
JU10
C22
1µF
ONL
JU11
INL
POUT
Figure 2. MAX1765 EV Kit Schematic (Right Side)
_______________________________________________________________________________________
5
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