3.5

0

I

(A)

OUT

1

2

3

4

5

6

7

8

9

10

V

= 1.8 V

F

= 500 kHz

OUT

SW

PV

V

IN

IN

_

5 V

12 V

3.0

2.5

2.0

1.5

1.0

0.5

0

90

100

0

Iout (A)

1

2

3

4

5

6

7

8

9

10

80

70

60

50

40

30

20

10

0

V

= 1.8 V

F

= 500 kHz

OUT

SW

PV

V

IN

IN

_

5 V

12 V

Operation Notes

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4

Operation Notes

In order to operate the EVM using a single power supply, the Vin Select jumper (P1) must be in the

default PVIN-VIN position shown in Figure 1. In this position, the PVin and Vin pins of the device are

connected together. The UVLO threshold of the EVM is approximately 4 V with 0.15 V of hysteresis. The

input voltage must be above the UVLO threshold in order for the device to startup. After startup, the

minimum input voltage to the device must be at least 4.5 V or (Vout + 0.7 V), whichever is greater. The

maximum operating input voltage for the device is 17 V. Refer to the LMZ317xx datasheet for further

information on the input voltage range, UVLO operation, and optional split power supply operation for

operating with PVin as low as 2.95 V when using an external Vbias supply.

After application of the proper input voltage, the output voltage of the device will ramp to its final value in

approximately 1.2 ms. If desired, this soft-start time can be increased by adding a capacitor to the SS/TR

test point as described above. Refer to the LMZ317xx datasheet for further information on adjusting the

soft-start time.

Table 1 lists the recommended switching frequencies for each of the Vout selections. These

recommendations cover operation over a wide range of input voltage and output load conditions. Several

factors such as duty cycle, minimum on-time, minimum off-time, and current limit influence selection of the

appropriate switching frequency. In some applications, other switching frequencies might be used for

particular output voltages, depending on the above factors. Refer to the LMZ317xx datasheet for further

information on switching frequency selection, including synchronization.

The EVM includes input and output capacitors to accommodate the entire range of input and output

voltage conditions. The actual capacitance required will depend on the input and output voltage conditions

of the particular application, along with the desired transient response. In most cases, the required output

capacitance will be less than that supplied on the EVM. Refer to the LMZ317xx datasheet for further

information on the minimum required I/O capacitance and transient response.

The LMZ317xx operates in pulse skip mode at light currents to improve light load efficiency (LLE mode).

At output voltages of less than 1.5 V, the pulse skipping may cause the output to rise when there is no

load to discharge the energy. A minimum load of 600 µA or less, depending on Vout, is required to keep

the output voltage within regulation. For the worst case condition of Vout = 0.6 V, a 1-k

Ω resistor would

provide a required minimum load of 600 µA. If the application requires an additional load to meet the

minimum load requirement, the additional load could be connected external to the EVM or installed in the

R16 position on the underside of the EVM. Refer to the LMZ317xx datasheet for further information on

LLE mode and determining the required minimum load.

5

Performance Data

Figure 2 through Figure 9 demonstrate the LMZ31710EVM performance with Vout = 1.8 V and

Fsw = 500 kHz. For data regarding the LMZ31707 and the LMZ31704 please see the product data sheet.

Figure 2. LMZ31710EVM Efficiency

Figure 3. LMZ31710EVM Power Dissipation

4

LMZ31710, LMZ31707 and LMZ31704 Simple Switcher® Power Module

SLVU895A – March 2013 – Revised June 2013

Evaluation Module

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